在Python中创建2D矩阵列表

Question

I am trying to create a list of 2d matrices, as per the illustration below:

list of 2d matrices

Basically, I want to start with a NxN matrix with all zeros and sequentially replace the 0's with 1's (as shown in the image). With each modification changing the 0's to 1's, I would like to output the matrix at that step and save it in a list or array.

For the first row of matrices in the illustration, I have this:

    dim = 4
    x=[]
    for i in range(0,dim):
        matrix = np.zeros((dim,dim))
        matrix[0,i] = 1
        x.append(matrix)
    m0 = x[0]
    m1 = x[0]+x[1]
    m2 = x[0]+x[1]+x[2]
    m3 = x[0]+x[1]+x[2]+x[3]

I would like to generalize this so I not only get the first row but the rest of the rows shown in the image and change the matrix size through 'dim'. I can't seem to figure this out. I'd appreciate any help with this.

Answer 1

This will do the job:

import numpy as np
dim = 4
x=[]
for i in range(dim):
    lst=[]
    matrix=np.zeros((dim,dim))
    vec=np.ones(i+1)
    for j in range(dim):
        matrix[0:i+1,j]=vec
        lst.append(np.copy(matrix))
    x.append(lst)
print(x)