create an array of matrix in python

Question

I would like create an array of matrix in python, without use numpy. My array is a global variable:

file_data= []

And this is my matrix inside a function:

ncols = 4
nrows = 200000
matrix = [[0] * ncols for i in range(nrows)]

after I fill the matrix and try to assign the matrix at the array:

file_data[ff]=matrix

But I obtain this error:

 file_data[ff]=matrix
IndexError: list assignment index out of range

Could someone help me?

Answer 1

Your file_data is an empty list, and therefore accessing file_data[ff] result in index out of range, whatever your ff is. To fix this, you can do file_data.append(matrix).