Python program keeps running and doesn't output

Question

Had a similar problem where the solution was a while loop that never met its end condition, but this time I'm using a nested for loop in another for loop, and don't see whether or not it is an infinite loop. If anybody could take a look and see what I'm missing. I have a screenshot of the terminal, you can see there's only a blank line indicating that it's still running. Here's the code:

import stdarray
import stdio


# Entry point (DO NOT EDIT).
def main():
    a = stdarray.readFloat2D()
    c = _transpose(a)
    for row in c:
        for v in row[:-1]:
            stdio.write(str(v) + ' ')
        stdio.writeln(row[-1])


# Returns the transpose of a.
def _transpose(a):
    # Get the dimensions of matrix a.
    m = len(a)  # number of rows in a
    n = len(a[0])  # number of columns in a

    # Create an n-by-m matrix c with all elements initialized to 0.0.
    c = stdarray.create2D(n, m, 0)

    # Fill in the elements of c such that c[i][j] = a[j][i], where 0 <= i < n and 0 <= j < m.
    for i in range(n):
        for j in range(m):
            c[i][j] = a[j][i]

    # Return c.
    return c


if __name__ == '__main__':
    main()

What is stdio? This is not part of python's standard libraries. — drum
– drum, Commented Apr 5, 2021 at 1:36
Neither is stdarray, I think. At least, pip didn't detect any matching thing to install. — Asker
– Asker, Commented Apr 5, 2021 at 1:37
Please provide the expected see MRE - Minimal, Reproducible Example. Show where the intermediate results deviate from the ones you expect. We should be able to paste a single block of your code into file, run it, and reproduce your problem. This also lets us test any suggestions in your context. We expect a minimal working example of the problem, including appropriate code to trace the internal operation. Your posted code fails to run. — Prune
– Prune, Commented Apr 5, 2021 at 1:38

Kronen · Accepted Answer · 2021-04-05 02:22:14Z

I suppose this comes from https://introcs.cs.princeton.edu/python/code/ which I found googling

If you look at the code in stdarray.py you can see that when calling stdarray.readFloat2D() it's expecting 2 integers (one each time) for number of rows and number of columns from your input and then n floats to fill that matrix. So if you input 3 and 4 as row and col you will need to input 12 floats to fill the matrix

def readFloat2D():
    """
    Read from sys.stdin and return a two-dimensional array of floats.
    Two integers at the beginning of sys.stdin define the array's
    dimensions.
    """
    rowCount = stdio.readInt()
    colCount = stdio.readInt()
    a = create2D(rowCount, colCount, 0.0)
    for row in range(rowCount):
        for col in range(colCount):
            print(f'row {row} col {col}')
            a[row][col] = stdio.readFloat()
    return a

Example of running the program:

2
3
4.3
2.5
6.7
4.5
7.8
2.0
2 3
4.3 2.5 6.7 
4.5 7.8 2.0

The 3 last lines is the output, the rest are the inputs.

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