python - 在python中添加矩阵中的元素

Question

我有这个矩阵:

mat = [[ 0 for x in range(row)] for y in range(column)]

我尝试向矩阵添加元素:

for x in range(row): # row is 2 
    for y in range(column): # column is 3
        mat[x][y] = int(input("number: "))

但是 shell 返回此错误:

Traceback (most recent call last):
File "C:\Users\Fr\Desktop\pr.py", line 13, in <module>
mat[x][y] = 12
IndexError: list assignment index out of range

如何向矩阵添加元素？

Answer 1

内部列表应基于列:

mat = [[ 0 for x in range(column)] for y in range(row)]

这是一个例子:

In [73]: row = 3
In [74]: column = 4
In [78]: mat = [[ 0 for x in range(column)] for y in range(row)]

In [79]: 

In [79]: for x in range(row): # row is 2 
             for y in range(column): # column is 3
                 mat[x][y] = 5
   ....:         

In [80]: mat
Out[80]: [[5, 5, 5, 5], [5, 5, 5, 5], [5, 5, 5, 5]]