在Python中：如何将稀疏矩阵写入CSV文件？

Question

I am a newbie to Python. I have been given a script which generates random numbers and puts them in a 126x81 sparse matrix. I would like to generate a csv file with: Cell_ID ; Cell_X ; Cell_Y ; Val . Cell X and Y are of course the coordinates for each cell. The script I have has a loop which generates an "outputs.csv" file, but in it data are not displayed the way I want them (there are square brackets at the beginning/end of each line and there are ellipsis [...] in place of some values). To sum up, I am not able to read the whole content of the matrix.

If I could, I would upload a picture to show you how I would like these data to look like when read in Notepad or Excel, but I am not allowed to do so. However, these data should look like a typical csv file with each value aligned under its column. Thank you for your help guys! :)

Answer 1

Since the standard library supports csv, let's use it:

import numpy
import csv

N = 126
M = 81

g = numpy.random.rand(N, M)

with open('test.csv', 'w') as f:
    writer = csv.writer(f)
    writer.writerow(['x', 'y', 'value'])
    for (n, m), val in numpy.ndenumerate(g):
        writer.writerow([n, m, val])