Array size exchange with numpy

Use Numpy to implement array dimension exchange

Numpy is a powerful Python library for scientific calculations and data processing. It contains a wealth of functions and tools that can easily perform various operations on arrays, one of which is the exchange of array dimensions. This article will introduce how to use Numpy to implement array dimension exchange and give specific code examples.

First, we need to import the Numpy library:

import numpy as np

Next, we can create a multidimensional array. For convenience of explanation, we first create a 3-dimensional array:

arr = np.array([[[1, 2, 3], [4, 5, 6]], [[7, 8, 9 ], [10, 11, 12]]])

Now, we can use the transpose function to exchange array dimensions. The transpose function can accept a parameter to specify the order of dimensions.

arr_transposed = np.transpose(arr, (2, 0, 1))
print(arr_transposed)

In the above example, we change the dimension order of the original array arr from (0, 1, 2) is exchanged for (2, 0, 1). The result will move the first dimension of the original array to the end, the second dimension to the first position, and the third dimension to the second position.

Run the above code, the output is:

[[[ 1 4]
[ 7 10]]

[[ 2 5]
[ 8 11 ]]

[[ 3 6]
[ 9 12]]]

We can see that the dimensions of the original array have been successfully exchanged. The first two-dimensional array becomes [[1, 4], [7, 10]], the second two-dimensional array becomes [[2, 5], [8, 11]], and the third two-dimensional array becomes [[2, 5], [8, 11]]. The dimensional array becomes [[3, 6], [9, 12]].

In addition to using the transpose function, Numpy also provides some other functions for operating on array dimensions, such as the swapaxes function and the rollaxis function. You can choose the appropriate function to operate according to your specific needs.

import numpy as np

arr = np.array([[[1, 2, 3], [4, 5, 6]], [[7, 8, 9], [10, 11, 12]])

Use swapaxes function to swap array dimensions

arr_swapped = np.swapaxes(arr, 0, 2)
print(arr_swapped)

Use rollaxis function to exchange array dimensions

arr_rolled = np.rollaxis(arr, 2, 0)
print(arr_rolled)

In the above code, we respectively The swapaxes function and the rollaxis function are used to exchange array dimensions. The swapaxes function accepts two parameters to specify the dimensions to be swapped, while the rollaxis function accepts three parameters, which are the array to be operated on, the dimension to be moved, and the position to move to.

To summarize, using Numpy to swap array dimensions is very simple. Just import the Numpy library and use the functions provided in it. The above code provides examples of using the transpose function, swapaxes function and rollaxis function to exchange array dimensions. You can choose the appropriate function to use according to your specific needs.

I hope this article is helpful to you, and I wish you happy programming in the Numpy world!

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