1164 lines
19 KiB
Python
1164 lines
19 KiB
Python
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qha = {
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"q1": "1. Import the numpy package under the name `np` (★☆☆)",
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"h1": "hint: import … as ",
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"a1":
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"""
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import numpy as np
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""",
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"q2": "2. Print the numpy version and the configuration (★☆☆)",
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"h2": "hint: np.__version__, np.show_config)",
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"a2":
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"""
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""",
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"q3": "3. Create a null vector of size 10 (★☆☆)",
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"h3": "hint: np.zeros",
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"a3":
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"""
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""",
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"q4": "4. How to find the memory size of any array (★☆☆)",
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"h4": "hint: size, itemsize",
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"a4":
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"""
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""",
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"q5": "5. How to get the documentation of the numpy add function from the command line? (★☆☆)",
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"h5": "hint: np.info",
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"a5":
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"""
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""",
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"q6": "6. Create a null vector of size 10 but the fifth value which is 1 (★☆☆)",
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"h6": "hint: array[4]",
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"a6":
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"""
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""",
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"q7": "7. Create a vector with values ranging from 10 to 49 (★☆☆)",
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"h7": "hint: arange",
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"a7":
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"""
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""",
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"q8": "8. Reverse a vector (first element becomes last) (★☆☆)",
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"h8": "hint: array[::-1]",
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"a8":
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"""
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""",
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"q9": "9. Create a 3x3 matrix with values ranging from 0 to 8 (★☆☆)",
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"h9": "hint: reshape",
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"a9":
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"""
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""",
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"q10": "10. Find indices of non-zero elements from [1,2,0,0,4,0] (★☆☆)",
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"h10": "hint: np.nonzero",
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"a10":
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"""
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""",
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"q11": "11. Create a 3x3 identity matrix (★☆☆)",
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"h11": "hint: np.eye",
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"a11":
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"""
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""",
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"q12": "12. Create a 3x3x3 array with random values (★☆☆)",
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"h12": "hint: np.random.random",
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"a12":
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"""
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""",
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"q13": "",
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"h13": "hint: ",
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"a13":
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"""
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""",
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"q14": "",
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"h14": "hint: ",
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"a14":
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"""
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""",
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"q15": "",
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"h15": "hint: ",
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"a15":
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"""
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""",
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"q16": "",
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"h16": "hint: ",
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"a16":
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"""
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""",
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"q17": "",
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"h17": "hint: ",
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"a17":
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"""
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""",
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"q18": "",
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"h18": "hint: ",
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"a18":
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"""
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""",
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"q19": "",
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"h19": "hint: ",
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"a19":
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"""
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""",
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"q20": "",
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"h20": "hint: ",
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"a20":
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"""
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""",
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"q21": "",
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"h21": "hint: ",
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"a21":
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"""
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""",
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"q22": "",
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"h22": "hint: ",
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"a22":
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"""
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""",
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"q23": "",
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"h23": "hint: ",
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"a23":
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"""
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""",
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"q24": "",
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"h24": "hint: ",
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"a24":
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"""
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""",
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"q25": "",
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"h25": "hint: ",
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"a25":
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"""
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""",
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"q26": "",
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"h26": "hint: ",
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"a26":
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"""
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""",
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"q27": "",
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"h27": "hint: ",
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"a27":
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"""
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""",
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"q28": "",
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"h28": "hint: ",
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"a28":
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"""
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""",
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"q29": "",
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"h29": "hint: ",
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"a29":
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"""
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""",
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"q30": "",
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"h30": "hint: ",
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"a30":
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"""
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""",
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"q31": "",
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"h31": "hint: ",
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"a31":
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"""
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""",
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"q32": "",
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"h32": "hint: ",
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"a32":
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"""
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""",
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"q33": "",
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"h33": "hint: ",
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"a33":
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"""
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""",
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"q34": "",
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"h34": "hint: ",
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"a34":
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"""
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""",
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"q35": "",
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"h35": "hint: ",
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"a35":
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"""
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""",
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"q36": "",
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"h36": "hint: ",
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"a36":
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"""
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""",
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"q37": "",
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"h37": "hint: ",
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"a37":
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"""
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""",
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"q38": "",
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"h38": "hint: ",
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"a38":
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"""
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""",
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"q39": "",
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"h39": "hint: ",
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"a39":
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"""
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""",
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"q40": "",
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"h40": "hint: ",
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"a40":
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"""
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""",
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"q41": "",
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"h41": "hint: ",
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"a41":
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"""
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""",
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"q42": "",
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"h42": "hint: ",
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"a42":
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"""
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""",
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"q43": "",
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"h43": "hint: ",
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"a43":
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"""
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""",
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"q44": "",
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"h44": "hint: ",
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"a44":
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"""
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""",
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"q45": "",
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"h45": "hint: ",
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"a45":
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"""
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""",
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"q46": "",
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"h46": "hint: ",
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"a46":
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"""
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""",
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"q47": "",
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"h47": "hint: ",
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"a47":
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"""
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""",
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"q48": "",
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"h48": "hint: ",
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"a48":
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"""
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""",
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"q49": "",
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"h49": "hint: ",
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"a49":
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"""
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""",
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"q50": "",
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"h50": "hint: ",
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"a50":
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"""
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""",
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"q51": "",
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"h51": "hint: ",
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"a51":
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"""
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""",
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"q52": "",
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"h52": "hint: ",
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"a52":
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"""
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""",
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"q53": "",
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"h53": "hint: ",
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"a53":
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"""
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""",
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"q54": "",
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"h54": "hint: ",
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"a54":
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"""
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""",
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"q55": "",
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"h55": "hint: ",
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"a55":
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"""
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""",
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"q56": "",
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"h56": "hint: ",
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"a56":
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"""
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""",
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"q57": "",
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"h57": "hint: ",
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"a57":
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"""
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""",
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"q58": "",
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"h58": "hint: ",
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"a58":
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"""
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""",
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"q59": "",
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"h59": "hint: ",
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"a59":
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"""
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""",
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"q60": "",
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"h60": "hint: ",
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"a60":
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"""
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""",
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"q61": "",
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"h61": "hint: ",
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"a61":
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"""
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""",
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"q62": "",
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"h62": "hint: ",
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"a62":
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"""
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""",
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"q63": "",
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"h63": "hint: ",
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"a63":
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"""
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""",
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"q64": "",
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"h64": "hint: ",
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"a64":
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"""
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""",
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"q65": "",
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"h65": "hint: ",
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"a65":
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"""
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""",
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"q66": "",
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"h66": "hint: ",
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"a66":
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"""
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""",
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"q67": "",
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"h67": "hint: ",
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"a67":
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"""
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""",
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"q68": "",
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"h68": "hint: ",
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"a68":
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"""
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""",
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"q69": "",
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"h69": "hint: ",
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"a69":
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"""
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""",
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"q70": "",
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"h70": "hint: ",
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"a70":
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"""
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""",
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"q71": "",
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"h71": "hint: ",
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"a71":
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"""
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""",
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"q72": "",
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"h72": "hint: ",
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"a72":
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"""
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""",
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"q73": "",
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"h73": "hint: ",
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"a73":
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"""
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""",
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"q74": "",
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"h74": "hint: ",
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"a74":
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"""
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""",
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"q75": "",
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"h75": "hint: ",
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"a75":
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"""
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""",
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"q76": "",
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"h76": "hint: ",
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"a76":
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"""
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""",
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"q77": "",
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"h77": "hint: ",
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"a77":
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"""
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""",
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"q78": "",
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"h78": "hint: ",
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"a78":
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"""
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""",
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"q79": "",
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"h79": "hint: ",
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"a79":
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"""
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""",
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"q80": "",
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"h80": "hint: ",
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"a80":
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"""
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""",
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"q81": "",
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"h81": "hint: ",
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"a81":
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"""
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""",
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"q82": "",
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"h82": "hint: ",
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"a82":
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"""
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""",
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"q83": "",
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"h83": "hint: ",
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"a83":
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"""
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""",
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"q84": "",
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"h84": "hint: ",
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"a84":
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"""
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""",
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"q85": "",
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"h85": "hint: ",
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"a85":
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"""
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""",
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"q86": "",
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"h86": "hint: ",
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"a86":
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"""
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""",
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"q87": "",
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"h87": "hint: ",
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"a87":
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"""
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""",
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"q88": "",
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"h88": "hint: ",
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"a88":
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"""
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""",
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"q89": "",
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"h89": "hint: ",
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"a89":
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"""
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""",
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"q90": "",
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"h90": "hint: ",
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"a90":
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"""
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""",
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"q91": "",
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"h91": "hint: ",
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"a91":
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"""
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""",
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"q92": "",
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"h92": "hint: ",
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"a92":
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"""
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""",
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"q93": "",
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"h93": "hint: ",
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"a93":
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"""
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""",
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"q94": "",
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"h94": "hint: ",
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"a94":
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"""
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""",
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"q95": "",
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"h95": "hint: ",
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"a95":
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"""
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""",
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"q96": "",
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"h96": "hint: ",
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"a96":
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"""
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""",
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"q97": "",
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"h97": "hint: ",
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"a97":
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"""
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""",
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"q98": "",
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"h98": "hint: ",
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"a98":
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"""
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""",
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"q99": "",
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"h99": "hint: ",
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"a99":
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"""
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""",
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"q100": "",
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"h100": "hint: ",
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"a100":
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"""
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""",
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}
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# ####
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#
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# (**hint**: np.random.random)
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#
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#
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#
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# #### 13. Create a 10x10 array with random values and find the minimum and maximum values (★☆☆)
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#
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# (**hint**: min, max)
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#
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#
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#
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# #### 14. Create a random vector of size 30 and find the mean value (★☆☆)
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#
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# (**hint**: mean)
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#
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#
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#
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# #### 15. Create a 2d array with 1 on the border and 0 inside (★☆☆)
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#
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# (**hint**: array\[1:-1, 1:-1\])
|
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#
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#
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#
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# #### 16. How to add a border (filled with 0's) around an existing array? (★☆☆)
|
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#
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# (**hint**: np.pad)
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#
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#
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#
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# #### 17. What is the result of the following expression? (★☆☆)
|
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#
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# (**hint**: NaN = not a number, inf = infinity)
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#
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#
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# ```python
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# 0 * np.nan
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# np.nan == np.nan
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# np.inf > np.nan
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# np.nan - np.nan
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# np.nan in set([np.nan])
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# 0.3 == 3 * 0.1
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# ```
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#
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# #### 18. Create a 5x5 matrix with values 1,2,3,4 just below the diagonal (★☆☆)
|
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#
|
|
# (**hint**: np.diag)
|
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#
|
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#
|
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#
|
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# #### 19. Create a 8x8 matrix and fill it with a checkerboard pattern (★☆☆)
|
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#
|
|
# (**hint**: array\[::2\])
|
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#
|
|
#
|
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#
|
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# #### 20. Consider a (6,7,8) shape array, what is the index (x,y,z) of the 100th element?
|
|
#
|
|
# (**hint**: np.unravel\_index)
|
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#
|
|
#
|
|
#
|
|
# #### 21. Create a checkerboard 8x8 matrix using the tile function (★☆☆)
|
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#
|
|
# (**hint**: np.tile)
|
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#
|
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#
|
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#
|
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# #### 22. Normalize a 5x5 random matrix (★☆☆)
|
|
#
|
|
# (**hint**: (x - mean) / std)
|
|
#
|
|
#
|
|
#
|
|
# #### 23. Create a custom dtype that describes a color as four unsigned bytes (RGBA) (★☆☆)
|
|
#
|
|
# (**hint**: np.dtype)
|
|
#
|
|
#
|
|
#
|
|
# #### 24. Multiply a 5x3 matrix by a 3x2 matrix (real matrix product) (★☆☆)
|
|
#
|
|
# (**hint**: np.dot | @)
|
|
#
|
|
#
|
|
#
|
|
# #### 25. Given a 1D array, negate all elements which are between 3 and 8, in place. (★☆☆)
|
|
#
|
|
# (**hint**: >, <=)
|
|
#
|
|
#
|
|
#
|
|
# #### 26. What is the output of the following script? (★☆☆)
|
|
#
|
|
# (**hint**: np.sum)
|
|
#
|
|
#
|
|
# ```python
|
|
# # Author: Jake VanderPlas
|
|
#
|
|
# print(sum(range(5),-1))
|
|
# from numpy import *
|
|
# print(sum(range(5),-1))
|
|
# ```
|
|
#
|
|
# #### 27. Consider an integer vector Z, which of these expressions are legal? (★☆☆)
|
|
#
|
|
#
|
|
# ```python
|
|
# Z**Z
|
|
# 2 << Z >> 2
|
|
# Z <- Z
|
|
# 1j*Z
|
|
# Z/1/1
|
|
# Z<Z>Z
|
|
# ```
|
|
#
|
|
# #### 28. What are the result of the following expressions?
|
|
#
|
|
#
|
|
# ```python
|
|
# np.array(0) / np.array(0)
|
|
# np.array(0) // np.array(0)
|
|
# np.array([np.nan]).astype(int).astype(float)
|
|
# ```
|
|
#
|
|
# #### 29. How to round away from zero a float array ? (★☆☆)
|
|
#
|
|
# (**hint**: np.uniform, np.copysign, np.ceil, np.abs)
|
|
#
|
|
#
|
|
#
|
|
# #### 30. How to find common values between two arrays? (★☆☆)
|
|
#
|
|
# (**hint**: np.intersect1d)
|
|
#
|
|
#
|
|
#
|
|
# #### 31. How to ignore all numpy warnings (not recommended)? (★☆☆)
|
|
#
|
|
# (**hint**: np.seterr, np.errstate)
|
|
#
|
|
#
|
|
#
|
|
# #### 32. Is the following expressions true? (★☆☆)
|
|
#
|
|
# (**hint**: imaginary number)
|
|
#
|
|
#
|
|
# ```python
|
|
# np.sqrt(-1) == np.emath.sqrt(-1)
|
|
# ```
|
|
#
|
|
# #### 33. How to get the dates of yesterday, today and tomorrow? (★☆☆)
|
|
#
|
|
# (**hint**: np.datetime64, np.timedelta64)
|
|
#
|
|
#
|
|
#
|
|
# #### 34. How to get all the dates corresponding to the month of July 2016? (★★☆)
|
|
#
|
|
# (**hint**: np.arange(dtype=datetime64\['D'\]))
|
|
#
|
|
#
|
|
#
|
|
# #### 35. How to compute ((A+B)\*(-A/2)) in place (without copy)? (★★☆)
|
|
#
|
|
# (**hint**: np.add(out=), np.negative(out=), np.multiply(out=), np.divide(out=))
|
|
#
|
|
#
|
|
#
|
|
# #### 36. Extract the integer part of a random array using 5 different methods (★★☆)
|
|
#
|
|
# (**hint**: %, np.floor, np.ceil, astype, np.trunc)
|
|
#
|
|
#
|
|
#
|
|
# #### 37. Create a 5x5 matrix with row values ranging from 0 to 4 (★★☆)
|
|
#
|
|
# (**hint**: np.arange)
|
|
#
|
|
#
|
|
#
|
|
# #### 38. Consider a generator function that generates 10 integers and use it to build an array (★☆☆)
|
|
#
|
|
# (**hint**: np.fromiter)
|
|
#
|
|
#
|
|
#
|
|
# #### 39. Create a vector of size 10 with values ranging from 0 to 1, both excluded (★★☆)
|
|
#
|
|
# (**hint**: np.linspace)
|
|
#
|
|
#
|
|
#
|
|
# #### 40. Create a random vector of size 10 and sort it (★★☆)
|
|
#
|
|
# (**hint**: sort)
|
|
#
|
|
#
|
|
#
|
|
# #### 41. How to sum a small array faster than np.sum? (★★☆)
|
|
#
|
|
# (**hint**: np.add.reduce)
|
|
#
|
|
#
|
|
#
|
|
# #### 42. Consider two random array A and B, check if they are equal (★★☆)
|
|
#
|
|
# (**hint**: np.allclose, np.array\_equal)
|
|
#
|
|
#
|
|
#
|
|
# #### 43. Make an array immutable (read-only) (★★☆)
|
|
#
|
|
# (**hint**: flags.writeable)
|
|
#
|
|
#
|
|
#
|
|
# #### 44. Consider a random 10x2 matrix representing cartesian coordinates, convert them to polar coordinates (★★☆)
|
|
#
|
|
# (**hint**: np.sqrt, np.arctan2)
|
|
#
|
|
#
|
|
#
|
|
# #### 45. Create random vector of size 10 and replace the maximum value by 0 (★★☆)
|
|
#
|
|
# (**hint**: argmax)
|
|
#
|
|
#
|
|
#
|
|
# #### 46. Create a structured array with `x` and `y` coordinates covering the \[0,1\]x\[0,1\] area (★★☆)
|
|
#
|
|
# (**hint**: np.meshgrid)
|
|
#
|
|
#
|
|
#
|
|
# #### 47. Given two arrays, X and Y, construct the Cauchy matrix C (Cij =1/(xi - yj))
|
|
#
|
|
# ##### (hint: np.subtract.outer)
|
|
#
|
|
#
|
|
#
|
|
# #### 48. Print the minimum and maximum representable value for each numpy scalar type (★★☆)
|
|
#
|
|
# (**hint**: np.iinfo, np.finfo, eps)
|
|
#
|
|
#
|
|
#
|
|
# #### 49. How to print all the values of an array? (★★☆)
|
|
#
|
|
# (**hint**: np.set\_printoptions)
|
|
#
|
|
#
|
|
#
|
|
# #### 50. How to find the closest value (to a given scalar) in a vector? (★★☆)
|
|
#
|
|
# (**hint**: argmin)
|
|
#
|
|
#
|
|
#
|
|
# #### 51. Create a structured array representing a position (x,y) and a color (r,g,b) (★★☆)
|
|
#
|
|
# (**hint**: dtype)
|
|
#
|
|
#
|
|
#
|
|
# #### 52. Consider a random vector with shape (100,2) representing coordinates, find point by point distances (★★☆)
|
|
#
|
|
# (**hint**: np.atleast\_2d, T, np.sqrt)
|
|
#
|
|
#
|
|
#
|
|
# #### 53. How to convert a float (32 bits) array into an integer (32 bits) in place?
|
|
#
|
|
# (**hint**: astype(copy=False))
|
|
#
|
|
#
|
|
#
|
|
# #### 54. How to read the following file? (★★☆)
|
|
#
|
|
# (**hint**: np.genfromtxt)
|
|
#
|
|
#
|
|
# ```
|
|
# 1, 2, 3, 4, 5
|
|
# 6, , , 7, 8
|
|
# , , 9,10,11
|
|
# ```
|
|
#
|
|
# #### 55. What is the equivalent of enumerate for numpy arrays? (★★☆)
|
|
#
|
|
# (**hint**: np.ndenumerate, np.ndindex)
|
|
#
|
|
#
|
|
#
|
|
# #### 56. Generate a generic 2D Gaussian-like array (★★☆)
|
|
#
|
|
# (**hint**: np.meshgrid, np.exp)
|
|
#
|
|
#
|
|
#
|
|
# #### 57. How to randomly place p elements in a 2D array? (★★☆)
|
|
#
|
|
# (**hint**: np.put, np.random.choice)
|
|
#
|
|
#
|
|
#
|
|
# #### 58. Subtract the mean of each row of a matrix (★★☆)
|
|
#
|
|
# (**hint**: mean(axis=,keepdims=))
|
|
#
|
|
#
|
|
#
|
|
# #### 59. How to sort an array by the nth column? (★★☆)
|
|
#
|
|
# (**hint**: argsort)
|
|
#
|
|
#
|
|
#
|
|
# #### 60. How to tell if a given 2D array has null columns? (★★☆)
|
|
#
|
|
# (**hint**: any, ~)
|
|
#
|
|
#
|
|
#
|
|
# #### 61. Find the nearest value from a given value in an array (★★☆)
|
|
#
|
|
# (**hint**: np.abs, argmin, flat)
|
|
#
|
|
#
|
|
#
|
|
# #### 62. Considering two arrays with shape (1,3) and (3,1), how to compute their sum using an iterator? (★★☆)
|
|
#
|
|
# (**hint**: np.nditer)
|
|
#
|
|
#
|
|
#
|
|
# #### 63. Create an array class that has a name attribute (★★☆)
|
|
#
|
|
# (**hint**: class method)
|
|
#
|
|
#
|
|
#
|
|
# #### 64. Consider a given vector, how to add 1 to each element indexed by a second vector (be careful with repeated indices)? (★★★)
|
|
#
|
|
# (**hint**: np.bincount | np.add.at)
|
|
#
|
|
#
|
|
#
|
|
# #### 65. How to accumulate elements of a vector (X) to an array (F) based on an index list (I)? (★★★)
|
|
#
|
|
# (**hint**: np.bincount)
|
|
#
|
|
#
|
|
#
|
|
# #### 66. Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique colors (★★★)
|
|
#
|
|
# (**hint**: np.unique)
|
|
#
|
|
#
|
|
#
|
|
# #### 67. Considering a four dimensions array, how to get sum over the last two axis at once? (★★★)
|
|
#
|
|
# (**hint**: sum(axis=(-2,-1)))
|
|
#
|
|
#
|
|
#
|
|
# #### 68. Considering a one-dimensional vector D, how to compute means of subsets of D using a vector S of same size describing subset indices? (★★★)
|
|
#
|
|
# (**hint**: np.bincount)
|
|
#
|
|
#
|
|
#
|
|
# #### 69. How to get the diagonal of a dot product? (★★★)
|
|
#
|
|
# (**hint**: np.diag)
|
|
#
|
|
#
|
|
#
|
|
# #### 70. Consider the vector \[1, 2, 3, 4, 5\], how to build a new vector with 3 consecutive zeros interleaved between each value? (★★★)
|
|
#
|
|
# (**hint**: array\[::4\])
|
|
#
|
|
#
|
|
#
|
|
# #### 71. Consider an array of dimension (5,5,3), how to mulitply it by an array with dimensions (5,5)? (★★★)
|
|
#
|
|
# (**hint**: array\[:, :, None\])
|
|
#
|
|
#
|
|
#
|
|
# #### 72. How to swap two rows of an array? (★★★)
|
|
#
|
|
# (**hint**: array\[\[\]\] = array\[\[\]\])
|
|
#
|
|
#
|
|
#
|
|
# #### 73. Consider a set of 10 triplets describing 10 triangles (with shared vertices), find the set of unique line segments composing all the triangles (★★★)
|
|
#
|
|
# (**hint**: repeat, np.roll, np.sort, view, np.unique)
|
|
#
|
|
#
|
|
#
|
|
# #### 74. Given an array C that is a bincount, how to produce an array A such that np.bincount(A) == C? (★★★)
|
|
#
|
|
# (**hint**: np.repeat)
|
|
#
|
|
#
|
|
#
|
|
# #### 75. How to compute averages using a sliding window over an array? (★★★)
|
|
#
|
|
# (**hint**: np.cumsum)
|
|
#
|
|
#
|
|
#
|
|
# #### 76. Consider a one-dimensional array Z, build a two-dimensional array whose first row is (Z\[0\],Z\[1\],Z\[2\]) and each subsequent row is shifted by 1 (last row should be (Z\[-3\],Z\[-2\],Z\[-1\]) (★★★)
|
|
#
|
|
# (**hint**: from numpy.lib import stride\_tricks)
|
|
#
|
|
#
|
|
#
|
|
# #### 77. How to negate a boolean, or to change the sign of a float inplace? (★★★)
|
|
#
|
|
# (**hint**: np.logical_not, np.negative)
|
|
#
|
|
#
|
|
#
|
|
# #### 78. Consider 2 sets of points P0,P1 describing lines (2d) and a point p, how to compute distance from p to each line i (P0\[i\],P1\[i\])? (★★★)
|
|
#
|
|
#
|
|
#
|
|
# #### 79. Consider 2 sets of points P0,P1 describing lines (2d) and a set of points P, how to compute distance from each point j (P\[j\]) to each line i (P0\[i\],P1\[i\])? (★★★)
|
|
#
|
|
#
|
|
#
|
|
# #### 80. Consider an arbitrary array, write a function that extract a subpart with a fixed shape and centered on a given element (pad with a `fill` value when necessary) (★★★)
|
|
#
|
|
# (**hint**: minimum, maximum)
|
|
#
|
|
#
|
|
#
|
|
# #### 81. Consider an array Z = \[1,2,3,4,5,6,7,8,9,10,11,12,13,14\], how to generate an array R = \[\[1,2,3,4\], \[2,3,4,5\], \[3,4,5,6\], ..., \[11,12,13,14\]\]? (★★★)
|
|
#
|
|
# (**hint**: stride\_tricks.as\_strided)
|
|
#
|
|
#
|
|
#
|
|
# #### 82. Compute a matrix rank (★★★)
|
|
#
|
|
# (**hint**: np.linalg.svd)
|
|
#
|
|
#
|
|
#
|
|
# #### 83. How to find the most frequent value in an array?
|
|
#
|
|
# (**hint**: np.bincount, argmax)
|
|
#
|
|
#
|
|
#
|
|
# #### 84. Extract all the contiguous 3x3 blocks from a random 10x10 matrix (★★★)
|
|
#
|
|
# (**hint**: stride\_tricks.as\_strided)
|
|
#
|
|
#
|
|
#
|
|
# #### 85. Create a 2D array subclass such that Z\[i,j\] == Z\[j,i\] (★★★)
|
|
#
|
|
# (**hint**: class method)
|
|
#
|
|
#
|
|
#
|
|
# #### 86. Consider a set of p matrices wich shape (n,n) and a set of p vectors with shape (n,1). How to compute the sum of of the p matrix products at once? (result has shape (n,1)) (★★★)
|
|
#
|
|
# (**hint**: np.tensordot)
|
|
#
|
|
#
|
|
#
|
|
# #### 87. Consider a 16x16 array, how to get the block-sum (block size is 4x4)? (★★★)
|
|
#
|
|
# (**hint**: np.add.reduceat)
|
|
#
|
|
#
|
|
#
|
|
# #### 88. How to implement the Game of Life using numpy arrays? (★★★)
|
|
#
|
|
#
|
|
#
|
|
# #### 89. How to get the n largest values of an array (★★★)
|
|
#
|
|
# (**hint**: np.argsort | np.argpartition)
|
|
#
|
|
#
|
|
#
|
|
# #### 90. Given an arbitrary number of vectors, build the cartesian product (every combinations of every item) (★★★)
|
|
#
|
|
# (**hint**: np.indices)
|
|
#
|
|
#
|
|
#
|
|
# #### 91. How to create a record array from a regular array? (★★★)
|
|
#
|
|
# (**hint**: np.core.records.fromarrays)
|
|
#
|
|
#
|
|
#
|
|
# #### 92. Consider a large vector Z, compute Z to the power of 3 using 3 different methods (★★★)
|
|
#
|
|
# (**hint**: np.power, \*, np.einsum)
|
|
#
|
|
#
|
|
#
|
|
# #### 93. Consider two arrays A and B of shape (8,3) and (2,2). How to find rows of A that contain elements of each row of B regardless of the order of the elements in B? (★★★)
|
|
#
|
|
# (**hint**: np.where)
|
|
#
|
|
#
|
|
#
|
|
# #### 94. Considering a 10x3 matrix, extract rows with unequal values (e.g. \[2,2,3\]) (★★★)
|
|
#
|
|
#
|
|
#
|
|
# #### 95. Convert a vector of ints into a matrix binary representation (★★★)
|
|
#
|
|
# (**hint**: np.unpackbits)
|
|
#
|
|
#
|
|
#
|
|
# #### 96. Given a two dimensional array, how to extract unique rows? (★★★)
|
|
#
|
|
# (**hint**: np.ascontiguousarray | np.unique)
|
|
#
|
|
#
|
|
#
|
|
# #### 97. Considering 2 vectors A & B, write the einsum equivalent of inner, outer, sum, and mul function (★★★)
|
|
#
|
|
# (**hint**: np.einsum)
|
|
#
|
|
#
|
|
#
|
|
# #### 98. Considering a path described by two vectors (X,Y), how to sample it using equidistant samples (★★★)?
|
|
#
|
|
# (**hint**: np.cumsum, np.interp)
|
|
#
|
|
#
|
|
#
|
|
# #### 99. Given an integer n and a 2D array X, select from X the rows which can be interpreted as draws from a multinomial distribution with n degrees, i.e., the rows which only contain integers and which sum to n. (★★★)
|
|
#
|
|
# (**hint**: np.logical\_and.reduce, np.mod)
|
|
#
|
|
#
|
|
#
|
|
# #### 100. Compute bootstrapped 95% confidence intervals for the mean of a 1D array X (i.e., resample the elements of an array with replacement N times, compute the mean of each sample, and then compute percentiles over the means). (★★★)
|
|
#
|
|
# (**hint**: np.percentile)
|
|
#
|