在Python中初始化空矩阵 [英] Initialize empty matrix in Python

问题描述

我正在尝试在Python中转换MATLAB代码.我不知道如何在Python中初始化空矩阵.

I am trying to convert a MATLAB code in Python. I don't know how to initialize empty matrix in Python.

MATLAB代码:

demod4(1) = [];

我在Python中尝试过

I tried in Python

demod4[0] = array([])

但它给出了错误:

only length-1 arrays can be converted to Python scalars

推荐答案

如果您使用的是 numpy

If you are using numpy arrays, you initialize to 0, by specifying the expected matrix size:

import numpy as np
d = np.zeros((2,3))

>>> d
    [[ 0.  0.  0.]
     [ 0.  0.  0.]]

这等同于MATLAB的:

This would be the equivalent of MATLAB 's:

d = zeros(2,3);

您还可以再次使用预期的尺寸/大小来初始化一个空数组

You can also initialize an empty array, again using the expected dimensions/size

d = np.empty((2,3))

如果您不使用 numpy，则最接近于 MATLAB 的 d = [](即零大小矩阵)将使用一个空列表，然后使用

If you are not using numpy, the closest somewhat equivalent to MATLAB's d = [] (i.e., a zero-size matrix) would be using an empty list and then

附加值(用于填充向量)

append values (for filling a vector)

d = []
d.append(0)
d.append(1)
>>> d                                                                     
[0, 1]

或附加列表(用于填充矩阵行或列):

or append lists (for filling a matrix row or column):

d = []                                                                
d.append(range(0,2))                                                    
d.append(range(2,4))                                                  
>>> d                                                                     
[[0, 1], [2, 3]]

另见:

初始化一个 numpy 数组(SO)

NumPy数组初始化(用相同的值填充)(SO)

如何创建一个空数组/矩阵在NumPy中?(SO)

适用于MATLAB用户的NumPy

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