General Array Creation Functions

NumPy also has array creation functions that can automatically create an array of a given shape (dimensions). Here are the most common ones:

zeros();
ones();
full().

zeros()

The name of this function speaks for itself: it creates an array of zeros of a given shape. The shape of the array is specified via the shape parameter and can either be an integer (size of a 1D array) or a tuple of integers for higher-dimensional arrays.


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import numpy as np
# Сreating a 1D array of zeros with 5 elements
zeros_1d = np.zeros(5)
print(zeros_1d)
# Сreating a 1D array of zeros with specifying dtype
zeros_1d_int = np.zeros(5, dtype=np.int8)
print(zeros_1d_int)
# Сreating a 2D array of zeros of shape 5x3
zeros_2d = np.zeros((5, 3))
print(zeros_2d)

As you can see, we can also specify the dtype parameter in the same way we did for other types of arrays.

ones()

This function is similar to the zeros() function, but instead of an array of zeros, it creates an array of ones.


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import numpy as np
# Сreating a 1D array of ones with 5 elements
ones_1d = np.ones(5)
print(ones_1d)
# Сreating a 1D array of ones with specifying dtype
ones_1d_int = np.ones(5, dtype=np.int8)
print(ones_1d_int)
# Сreating a 2D array of ones of shape 5x3
ones_2d = np.ones((5, 3))
print(ones_2d)

full()

The numpy.full() function is similar to the functions mentioned above, but it has a second parameter, fill_value, to specify the value to fill the array with. Its first parameter, shape, can be either an integer or a tuple of integers:


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import numpy as np
# Сreate an array of fours of size 5
array_fours_1d = np.full(5, 4)
# Сreate an array of fives of shape 4x2
array_fives_2d = np.full((4, 2), 5)
print(f'1D fours array: {array_fours_1d}')
print(f'2D fives array:\n{array_fives_2d}')

More Applications

All of these functions have more use cases than simply being placeholders. They are quite often used directly in mathematical operations in linear algebra. They can be applied in various fields of machine and deep learning, such as image processing.

Завдання

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Create a one-dimensional array of zeros with a size of 5 and assign it to zeros_array_1d.
Create a two-dimensional array of zeros with a shape of 2x4 and assign it to zeros_array_2d.
Create a one-dimensional array of ones with a size of 3 and assign it to ones_array_1d.
Create a two-dimensional array of ones with a shape of 2x3 and assign it to ones_array_2d.
Create a two-dimensional array of sevens with a shape of 2x2 and assign it to sevens_array_2d.

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