What is the way to swap dimensions of numpy array?

How numpy exchanges array dimensions, specific code examples are required

numpy is a powerful numerical calculation library in Python, which provides many convenient functions and methods to handle array. In numpy we can easily swap the dimensions of an array. This article will introduce how to use functions in the numpy library to exchange array dimensions and provide specific code examples.

In numpy, you can use the transpose() and swapaxes() functions to swap array dimensions. These two functions are used to perform dimension transformation on N-dimensional arrays, and can easily exchange the order of dimensions.

First, let’s look at the transpose() function. This function can accept a tuple consisting of dimension indexes as input parameters, which is used to specify the exchange order of dimensions. For example, we have a two-dimensional array arr. If we want to exchange its dimensions, we can use the transpose() function as follows:

import numpy as np

arr = np.array([[1, 2], [3, 4]])
print("原数组：
", arr)

# 交换维度
arr_transposed = np.transpose(arr)
print("交换维度后的数组：
", arr_transposed)

The running result is as follows:

原数组：
 [[1 2]
 [3 4]]
交换维度后的数组：
 [[1 3]
 [2 4]]

You can see that the rows of the original array become the columns of the swapped array, and the columns become the rows of the swapped array, achieving dimension exchange.

Another function is the swapaxes() function. This function accepts the indices of two dimensions as input parameters, specifying the dimension to be swapped. For example, if we want to swap the first and second dimensions of a three-dimensional array, we can use the swapaxes() function as follows:

import numpy as np

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

# 交换维度
arr_swapped = np.swapaxes(arr, 0, 1)
print("交换维度后的数组：
", arr_swapped)

The running result is as follows:

原数组：
 [[[ 1  2  3]
  [ 4  5  6]]

 [[ 7  8  9]
  [10 11 12]]]
交换维度后的数组：
 [[[ 1  2  3]
  [ 7  8  9]]

 [[ 4  5  6]
  [10 11 12]]]

As you can see, the first and second dimensions of the original array are exchanged, realizing dimension exchange.

Through the transpose() and swapaxes() functions, we can easily exchange array dimensions. This is very useful for processing data in different dimensional orders and can improve the flexibility and efficiency of data processing.

To summarize, this article introduces the transpose() and swapaxes() functions in the numpy library, which are used to exchange array dimensions. Both functions can easily exchange the dimensions of arrays to meet the needs of different data processing. I hope this article will help you learn numpy array operations.

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