Matrix input result (Python)

Question

I have this code wrote in python,used to input a matrix:

def gestionmatrice():       

    print("Entrez la matrice,séparé par des espaces pour chaques colonnes")
    print("une rangée par ligne,et faites un ligne vide pour terminer")
    matrix = []
    while True:
        line = input()
        if not line: break
        values = line.split()
        row = [int(value) for value in values]
        matrix.append(row)

    print(matrix)

The user input the matrix by entering all desired int value per row separated by a space,then press enter to confirm the row and input the next one. To finish, user have to input a blank row and press enter. At the end,I want to see the matrix by printing it; the problem is that it doesn't work correctly; if for example the user input 1 2 3 and then 4 5 6 on the next row, the print(matrix) will result as:[[1, 2, 3], [4, 5, 6]].It would be supposed to print 1 2 3 4 5 6 so something doesn't work.What has to be modified? Thanks in advance.

Could you make clear in the question body what you would expect the output to be? I tried to salvage it in my edit but I couldn't make it out. — anon582847382
– anon582847382, Commented Apr 12, 2014 at 20:00
actually I would like the output to display 1 2 3 and on the row under,4 5 6 aligned with the 1 2 3. — Jon_Computer
– Jon_Computer, Commented Apr 12, 2014 at 20:01
What happens when there's a 10? Do you want everything to be aligned? — Scorpion_God
– Scorpion_God, Commented Apr 12, 2014 at 20:16

anon582847382 · Accepted Answer · 2014-11-01 15:35:26Z

1

You can print out a matrix in Python like this:

def print_matrix(matrix):
    print('\n'.join([' '.join(map(str, row)) for row in matrix]))

Here's a get matrix function:

def get_matrix():
    matrix = []
    line = input()
    while line:
        matrix.append(map(int, line.split()))
        line = input()
    return matrix

Demo:

>>> matrix = get_matrix()
1 2 3
4 5 6
7 8 9

>>> print_matrix(matrix)
1 2 3
4 5 6
7 8 9

edited Nov 1, 2014 at 15:35

anon582847382

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answered Apr 12, 2014 at 20:06

Scorpion_God

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Comments

anon582847382 · Accepted Answer · 2014-04-12 20:09:11Z

0

I'm not sure quite why you want it to be like that, but you could do something like:

Instead of print(matrix), do:

>>> print(*(' '.join(map(str, sub)) for sub in matrix), sep='\n')
1 2 3
4 5 6

That is the quick fix.

edited Apr 12, 2014 at 20:09

answered Apr 12, 2014 at 20:04

anon582847382

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1 Comment

anon582847382 Over a year ago

@HaiVu Realised that pretty much as you posted, edited and thank you.

AdrienNK · Accepted Answer · 2014-04-12 20:02:59Z

0

[[1, 2, 3], [4, 5, 6]]

is the default printing of a matrix (in many language, not only python).

To achieve what you want you have to do something like

import sys
for i in xrange(2):
    for j in xrange(3):
        sys.stdout.write(str(matrix[i,j] + " "))
    sys.stdout.write("\n")

answered Apr 12, 2014 at 20:02

AdrienNK

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2 Comments

Jon_Computer Over a year ago

oh really? I thought I was wrong since I thought [[1, 2, 3], [4, 5, 6]] was just like 2 list in a big list,and not a matrix.So its still a matrix,and its just normal that it result a display like this [[1, 2, 3], [4, 5, 6]]? Thanks

AdrienNK Over a year ago

@Jon_Computer That's "a" way to represent matrices, but by itself python will never print a matrix like you originally wanted to.

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