Overview:
- Given an n-dimensional matrix, its contents can be checked whether all of its elements evaluate to True or any of its elements evaluate to True.
- The all() method of numpy.ndarray can be used to check whether all of the elements of an ndarray object evaluate to True.
- The any() method of numpy.ndarray can be used to find whether any of the elements of an ndarray object evaluate to True.
- These tests can be performed considering the n-dimensional array as a flat array or over a specific axis of the array.
- When the axis is not specified these operations are performed on the whole array and when the axis is specified these operations are performed on the given axis.
- While all() method performs a logical AND operation on the ndarray elements or the elements along the given axis of the ndarray, the any() method performs a logical OR operation.
Example: numpy.ndarray.all()
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import numpy as np
# Create a 3 dimensional array Array_3d = np.arange(9).reshape(3,3)
print("2 dimensional input array:") print(Array_3d)
print("Return values from all():") print("-------------------------") print("When no axis is specified:") print(Array_3d.all()) print("When no axis is specified and keepdims = True:") print(Array_3d.all(keepdims=True)) print("When axis=0") print(Array_3d.all(axis=0)) print("When axis=0, keepdims = True:") print(Array_3d.all(axis=0, keepdims=True)) |
Output:
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2 dimensional input array: [[0 1 2] [3 4 5] [6 7 8]] Return values from all(): ------------------------- When no axis is specified: False When no axis is specified and keepdims = True: [[False]] When axis=0 [False True True] When axis=0, keepdims = True: [[False True True]] |
Example: numpy.ndarray.any()
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import numpy as np
# Create a 3 dimensional array Array_3d = np.arange(9).reshape(3,3)
print("2 dimensional input array:") print(Array_3d)
print("Return values from any():") print("-------------------------") print("When no axis is specified:") print(Array_3d.any()) print("When no axis is specified and keepdims = True:") print(Array_3d.any(keepdims=True)) print("When axis=0") print(Array_3d.any(axis=0)) print("When axis=0, keepdims = True:") print(Array_3d.any(axis=0, keepdims=True)) |
Output:
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2 dimensional input array: [[0 1 2] [3 4 5] [6 7 8]] Return values from any(): ------------------------- When no axis is specified: True When no axis is specified and keepdims = True: [[ True]] When axis=0 [ True True True] When axis=0, keepdims = True: [[ True True True]] |