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replace the solution of problem 66 and set the difficulty

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Fisher Wang 2021-03-11 17:10:53 +08:00
parent 0d8a4a025b
commit 8527c7c83c
6 changed files with 7 additions and 37 deletions
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2
100_Numpy_exercises.ipynb
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@ -989,7 +989,7 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"#### 66. Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique colors (★★★)"
"#### 66. Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique colors (★★☆)"
]
},
{

2
100_Numpy_exercises.md
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@ -178,7 +178,7 @@ np.sqrt(-1) == np.emath.sqrt(-1)
#### 65. How to accumulate elements of a vector (X) to an array (F) based on an index list (I)? (★★★)
#### 66. Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique colors (★★★)
#### 66. Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique colors (★★☆)
#### 67. Considering a four dimensions array, how to get sum over the last two axis at once? (★★★)

2
100_Numpy_exercises_with_hints.md
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@ -178,7 +178,7 @@ np.sqrt(-1) == np.emath.sqrt(-1)
`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 (★★★)
#### 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))`

14
100_Numpy_exercises_with_hints_with_solutions.md
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@ -674,21 +674,11 @@ I = [1,3,9,3,4,1]
F = np.bincount(I,X)
print(F)
```
#### 66. Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique colors (★★★)
#### 66. Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique colors (★★☆)
`hint: np.unique`
```python
# Author: Nadav Horesh
w,h = 16,16
I = np.random.randint(0,2,(h,w,3)).astype(np.ubyte)
# The parenthesis around 256*256 ensure the dtpye promoted to uint32 properly.Otherwise the first term will overflow.
F = I[...,0]*(256*256) + I[...,1]*256 +I[...,2]
n = len(np.unique(F))
print(np.unique(I))
# Another solution
# Author: Fisher Wangg
# Author: Fisher Wang
w, h = 16, 16
img = np.random.randint(0, 256, (w, h, 3)).astype(np.ubyte)

12
100_Numpy_exercises_with_solutions.md
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@ -674,20 +674,10 @@ I = [1,3,9,3,4,1]
F = np.bincount(I,X)
print(F)
```
#### 66. Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique colors (★★★)
#### 66. Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique colors (★★☆)
```python
# Author: Nadav Horesh
w,h = 16,16
I = np.random.randint(0,2,(h,w,3)).astype(np.ubyte)
# The parenthesis around 256*256 ensure the dtpye promoted to uint32 properly.Otherwise the first term will overflow.
F = I[...,0]*(256*256) + I[...,1]*256 +I[...,2]
n = len(np.unique(F))
print(np.unique(I))
# Another solution
# Author: Fisher Wang
w, h = 16, 16

12
source/exercises100.ktx
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@ -855,22 +855,12 @@ F = np.bincount(I,X)
print(F)
< q66
Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique colors (★★★)
Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique colors (★★☆)
< h66
hint: np.unique
< a66
# Author: Nadav Horesh
w,h = 16,16
I = np.random.randint(0,2,(h,w,3)).astype(np.ubyte)
# The parenthesis around 256*256 ensure the dtpye promoted to uint32 properly.Otherwise the first term will overflow.
F = I[...,0]*(256*256) + I[...,1]*256 +I[...,2]
n = len(np.unique(F))
print(np.unique(I))
# Another solution
# Author: Fisher Wang
w, h = 16, 16