Updated generated files

100_Numpy_exercises.md

@@ -3,12 +3,15 @@
 
 # 100 numpy exercises
 
-This is a collection of exercises that have been collected in the numpy mailing list, on stack overflow
+This is a collection of exercises that have been collected in the numpy mailing list, on stack 
+overflow
 and in the numpy documentation. The goal of this collection is to offer a quick reference for both old
-and new users but also to provide a set of exercises for those who teach.
+and new 
+users but also to provide a set of exercises for those who teach.
 
 
-If you find an error or think you've a better way to solve some of them, feel
+If you find an error or think you've a better way to
+ solve some of them, feel
 free to open an issue at <https://github.com/rougier/numpy-100>.
 File automatically generated. See the documentation to update questions/answers/hints programmatically.
 

100_Numpy_exercises_with_hints.md

@@ -3,12 +3,15 @@
 
 # 100 numpy exercises
 
-This is a collection of exercises that have been collected in the numpy mailing list, on stack overflow
+This is a collection of exercises that have been collected in the numpy mailing list, on stack 
+overflow
 and in the numpy documentation. The goal of this collection is to offer a quick reference for both old
-and new users but also to provide a set of exercises for those who teach.
+and new 
+users but also to provide a set of exercises for those who teach.
 
 
-If you find an error or think you've a better way to solve some of them, feel
+If you find an error or think you've a better way to
+ solve some of them, feel
 free to open an issue at <https://github.com/rougier/numpy-100>.
 File automatically generated. See the documentation to update questions/answers/hints programmatically.
 
@@ -197,9 +200,9 @@ np.sqrt(-1) == np.emath.sqrt(-1)
 #### 74. Given a sorted array C that corresponds to 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`
+`hint: np.cumsum, from numpy.lib.stride_tricks import sliding_window_view (np>=1.20.0)`
 #### 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`
+`hint: from numpy.lib import stride_tricks, from numpy.lib.stride_tricks import sliding_window_view (np>=1.20.0)`
 #### 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])? (★★★)
@@ -209,19 +212,19 @@ np.sqrt(-1) == np.emath.sqrt(-1)
 #### 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`
+`hint: stride_tricks.as_strided, from numpy.lib.stride_tricks import sliding_window_view (np>=1.20.0)`
 #### 82. Compute a matrix rank (★★★)
-`hint: np.linalg.svd`
+`hint: np.linalg.svd, np.linalg.matrix_rank`
 #### 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`
+`hint: stride_tricks.as_strided, from numpy.lib.stride_tricks import sliding_window_view (np>=1.20.0)`
 #### 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`
+`hint: np.add.reduceat, from numpy.lib.stride_tricks import sliding_window_view (np>=1.20.0)`
 #### 88. How to implement the Game of Life using numpy arrays? (★★★)
 `No hints provided...`
 #### 89. How to get the n largest values of an array (★★★)

100_Numpy_exercises_with_hints_with_solutions.md

@@ -3,12 +3,15 @@
 
 # 100 numpy exercises
 
-This is a collection of exercises that have been collected in the numpy mailing list, on stack overflow
+This is a collection of exercises that have been collected in the numpy mailing list, on stack 
+overflow
 and in the numpy documentation. The goal of this collection is to offer a quick reference for both old
-and new users but also to provide a set of exercises for those who teach.
+and new 
+users but also to provide a set of exercises for those who teach.
 
 
-If you find an error or think you've a better way to solve some of them, feel
+If you find an error or think you've a better way to
+ solve some of them, feel
 free to open an issue at <https://github.com/rougier/numpy-100>.
 File automatically generated. See the documentation to update questions/answers/hints programmatically.
 
@@ -806,7 +809,7 @@ A = np.repeat(np.arange(len(C)), C)
 print(A)
 ```
 #### 75. How to compute averages using a sliding window over an array? (★★★)
-`hint: np.cumsum`
+`hint: np.cumsum, from numpy.lib.stride_tricks import sliding_window_view (np>=1.20.0)`
 
 ```python
 # Author: Jaime Fernández del Río
@@ -817,9 +820,17 @@ def moving_average(a, n=3) :
     return ret[n - 1:] / n
 Z = np.arange(20)
 print(moving_average(Z, n=3))
+
+# Author: Jeff Luo (@Jeff1999)
+# make sure your NumPy >= 1.20.0
+
+from numpy.lib.stride_tricks import sliding_window_view
+
+Z = np.arange(20)
+print(sliding_window_view(Z, window_shape=3).mean(axis=-1))
 ```
 #### 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`
+`hint: from numpy.lib import stride_tricks, from numpy.lib.stride_tricks import sliding_window_view (np>=1.20.0)`
 
 ```python
 # Author: Joe Kington / Erik Rigtorp
@@ -831,6 +842,11 @@ def rolling(a, window):
     return stride_tricks.as_strided(a, shape=shape, strides=strides)
 Z = rolling(np.arange(10), 3)
 print(Z)
+
+# Author: Jeff Luo (@Jeff1999)
+
+Z = np.arange(10)
+print(sliding_window_view(Z, window_shape=3))
 ```
 #### 77. How to negate a boolean, or to change the sign of a float inplace? (★★★)
 `hint: np.logical_not, np.negative`
@@ -906,7 +922,7 @@ print(Z)
 print(R)
 ```
 #### 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`
+`hint: stride_tricks.as_strided, from numpy.lib.stride_tricks import sliding_window_view (np>=1.20.0)`
 
 ```python
 # Author: Stefan van der Walt
@@ -914,9 +930,14 @@ print(R)
 Z = np.arange(1,15,dtype=np.uint32)
 R = stride_tricks.as_strided(Z,(11,4),(4,4))
 print(R)
+
+# Author: Jeff Luo (@Jeff1999)
+
+Z = np.arange(1, 15, dtype=np.uint32)
+print(sliding_window_view(Z, window_shape=4))
 ```
 #### 82. Compute a matrix rank (★★★)
-`hint: np.linalg.svd`
+`hint: np.linalg.svd, np.linalg.matrix_rank`
 
 ```python
 # Author: Stefan van der Walt
@@ -925,6 +946,12 @@ Z = np.random.uniform(0,1,(10,10))
 U, S, V = np.linalg.svd(Z) # Singular Value Decomposition
 rank = np.sum(S > 1e-10)
 print(rank)
+
+# alternative solution:
+# Author: Jeff Luo (@Jeff1999)
+
+rank = np.linalg.matrix_rank(Z)
+print(rank)
 ```
 #### 83. How to find the most frequent value in an array?
 `hint: np.bincount, argmax`
@@ -934,7 +961,7 @@ Z = np.random.randint(0,10,50)
 print(np.bincount(Z).argmax())
 ```
 #### 84. Extract all the contiguous 3x3 blocks from a random 10x10 matrix (★★★)
-`hint: stride_tricks.as_strided`
+`hint: stride_tricks.as_strided, from numpy.lib.stride_tricks import sliding_window_view (np>=1.20.0)`
 
 ```python
 # Author: Chris Barker
@@ -945,6 +972,11 @@ i = 1 + (Z.shape[0]-3)
 j = 1 + (Z.shape[1]-3)
 C = stride_tricks.as_strided(Z, shape=(i, j, n, n), strides=Z.strides + Z.strides)
 print(C)
+
+# Author: Jeff Luo (@Jeff1999)
+
+Z = np.random.randint(0,5,(10,10))
+print(sliding_window_view(Z, window_shape=(3, 3)))
 ```
 #### 85. Create a 2D array subclass such that Z[i,j] == Z[j,i] (★★★)
 `hint: class method`
@@ -985,7 +1017,7 @@ print(S)
 # and 2 and 1, to remain with a (n,1) vector.
 ```
 #### 87. Consider a 16x16 array, how to get the block-sum (block size is 4x4)? (★★★)
-`hint: np.add.reduceat`
+`hint: np.add.reduceat, from numpy.lib.stride_tricks import sliding_window_view (np>=1.20.0)`
 
 ```python
 # Author: Robert Kern
@@ -1004,6 +1036,12 @@ k = 4
 
 windows = np.lib.stride_tricks.sliding_window_view(Z, (k, k))
 S = windows[::k, ::k, ...].sum(axis=(-2, -1))
+
+# Author: Jeff Luo (@Jeff1999)
+
+Z = np.ones((16, 16))
+k = 4
+print(sliding_window_view(Z, window_shape=(k, k))[::k, ::k].sum(axis=(-2, -1)))
 ```
 #### 88. How to implement the Game of Life using numpy arrays? (★★★)
 `No hints provided...`

100_Numpy_exercises_with_solutions.md

@@ -3,12 +3,15 @@
 
 # 100 numpy exercises
 
-This is a collection of exercises that have been collected in the numpy mailing list, on stack overflow
+This is a collection of exercises that have been collected in the numpy mailing list, on stack 
+overflow
 and in the numpy documentation. The goal of this collection is to offer a quick reference for both old
-and new users but also to provide a set of exercises for those who teach.
+and new 
+users but also to provide a set of exercises for those who teach.
 
 
-If you find an error or think you've a better way to solve some of them, feel
+If you find an error or think you've a better way to
+ solve some of them, feel
 free to open an issue at <https://github.com/rougier/numpy-100>.
 File automatically generated. See the documentation to update questions/answers/hints programmatically.
 
@@ -178,7 +181,7 @@ print(np.unravel_index(99,(6,7,8)))
 
 
 ```python
-Z = np.tile(np.eye(2), (4,4))
+Z = np.tile( np.array([[0,1],[1,0]]), (4,4))
 print(Z)
 ```
 #### 22. Normalize a 5x5 random matrix (★☆☆)
@@ -817,6 +820,14 @@ def moving_average(a, n=3) :
     return ret[n - 1:] / n
 Z = np.arange(20)
 print(moving_average(Z, n=3))
+
+# Author: Jeff Luo (@Jeff1999)
+# make sure your NumPy >= 1.20.0
+
+from numpy.lib.stride_tricks import sliding_window_view
+
+Z = np.arange(20)
+print(sliding_window_view(Z, window_shape=3).mean(axis=-1))
 ```
 #### 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]) (★★★)
 
@@ -831,6 +842,11 @@ def rolling(a, window):
     return stride_tricks.as_strided(a, shape=shape, strides=strides)
 Z = rolling(np.arange(10), 3)
 print(Z)
+
+# Author: Jeff Luo (@Jeff1999)
+
+Z = np.arange(10)
+print(sliding_window_view(Z, window_shape=3))
 ```
 #### 77. How to negate a boolean, or to change the sign of a float inplace? (★★★)
 
@@ -914,6 +930,11 @@ print(R)
 Z = np.arange(1,15,dtype=np.uint32)
 R = stride_tricks.as_strided(Z,(11,4),(4,4))
 print(R)
+
+# Author: Jeff Luo (@Jeff1999)
+
+Z = np.arange(1, 15, dtype=np.uint32)
+print(sliding_window_view(Z, window_shape=4))
 ```
 #### 82. Compute a matrix rank (★★★)
 
@@ -925,6 +946,12 @@ Z = np.random.uniform(0,1,(10,10))
 U, S, V = np.linalg.svd(Z) # Singular Value Decomposition
 rank = np.sum(S > 1e-10)
 print(rank)
+
+# alternative solution:
+# Author: Jeff Luo (@Jeff1999)
+
+rank = np.linalg.matrix_rank(Z)
+print(rank)
 ```
 #### 83. How to find the most frequent value in an array?
 
@@ -945,6 +972,11 @@ i = 1 + (Z.shape[0]-3)
 j = 1 + (Z.shape[1]-3)
 C = stride_tricks.as_strided(Z, shape=(i, j, n, n), strides=Z.strides + Z.strides)
 print(C)
+
+# Author: Jeff Luo (@Jeff1999)
+
+Z = np.random.randint(0,5,(10,10))
+print(sliding_window_view(Z, window_shape=(3, 3)))
 ```
 #### 85. Create a 2D array subclass such that Z[i,j] == Z[j,i] (★★★)
 
@@ -1004,6 +1036,12 @@ k = 4
 
 windows = np.lib.stride_tricks.sliding_window_view(Z, (k, k))
 S = windows[::k, ::k, ...].sum(axis=(-2, -1))
+
+# Author: Jeff Luo (@Jeff1999)
+
+Z = np.ones((16, 16))
+k = 4
+print(sliding_window_view(Z, window_shape=(k, k))[::k, ::k].sum(axis=(-2, -1)))
 ```
 #### 88. How to implement the Game of Life using numpy arrays? (★★★)
 

100_Numpy_random.ipynb

@@ -2,7 +2,7 @@
  "cells": [
   {
    "cell_type": "markdown",
-   "id": "bbe15f43",
+   "id": "a194d42e",
    "metadata": {},
    "source": [
     "# 100 numpy exercises\n",
@@ -18,7 +18,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "ed56e5f0",
+   "id": "a7fd49f7",
    "metadata": {},
    "source": [
     "File automatically generated. See the documentation to update questions/answers/hints programmatically."
@@ -26,7 +26,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "14866554",
+   "id": "b702d5a2",
    "metadata": {},
    "source": [
     "Run the `initialize.py` module, then call a random question with `pick()` an hint towards its solution with\n",
@@ -36,7 +36,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "af8b6f2a",
+   "id": "da60e1d0",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -46,7 +46,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "f13ecfd7",
+   "id": "9fb544fe",
    "metadata": {},
    "outputs": [],
    "source": [