How would I display the values of a selected column in Python array?

Question

How would I find the values from a certain column in an array? For example I have:

[1, 1, 2, 4, 1, 7, 1, 7, 6, 9]
[1, 2, 5, 3, 9, 1, 1, 1, 9, 1]
[7, 4, 5, 1, 8, 1, 2, 0, 0, 4]
[1, 4, 1, 1, 1, 1, 1, 1, 8, 5]
[9, 0, 0, 0, 0, 0, 1, 1, 9, 8]
[7, 4, 2, 1, 8, 2, 2, 2, 9, 7]
[7, 4, 2, 1, 7, 1, 1, 1, 0, 5]
[3, 4, 5, 3, 4, 5, 9, 1, 0, 9]
[0, 0, 5, 1, 1, 1, 9, 7, 7, 7]

If I wanted to list all of the values of column 5, how would I do this? I have figured out how to do this for the rows, but for the columns it is tricky, since they are all part of a separate list. I have not been able to find anything about this and I am very new to Python so I don't really know what I don't know.

An actual answer: use a list comprehension. [x[4] for x in list_2d] — cs95
– cs95, Commented Feb 17, 2018 at 4:59
This super works! Thank you! Just so I understand this better, what exactly is that function doing? — Drew
– Drew, Commented Feb 17, 2018 at 5:04
The first is a neat transposition trick. The second is a straightforward list comp iteration over each sublist. — cs95
– cs95, Commented Feb 17, 2018 at 5:06
Ok so if I wanted to display the value of a certain cell, would I apply the same sort of rule? — Drew
– Drew, Commented Feb 18, 2018 at 4:46

CodeIt · Accepted Answer · 2018-02-17 05:10:22Z

2

It's simple. Just use l[i][4] to print 5th column value.

l = [
            [1, 1, 2, 4, 1, 7, 1, 7, 6, 9],
            [1, 2, 5, 3, 9, 1, 1, 1, 9, 1],
            [7, 4, 5, 1, 8, 1, 2, 0, 0, 4],
            [1, 4, 1, 1, 1, 1, 1, 1, 8, 5],
            [9, 0, 0, 0, 0, 0, 1, 1, 9, 8],
            [7, 4, 2, 1, 8, 2, 2, 2, 9, 7],
            [7, 4, 2, 1, 7, 1, 1, 1, 0, 5],
            [3, 4, 5, 3, 4, 5, 9, 1, 0, 9],
            [0, 0, 5, 1, 1, 1, 9, 7, 7, 7]
        ]

for i in l:
    print(i[4])

# or simply use

[i[4] for i in l] #as pointed out by @COLDSPEED

# the above code will create a list with values from 5th column

See it in action here

edited Feb 17, 2018 at 5:10

answered Feb 17, 2018 at 5:01

CodeIt

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cs95 · Accepted Answer · 2018-02-19 03:11:44Z

0

For a two dimensional array, you can use array[row][column].

edited Feb 19, 2018 at 3:11

cs95

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answered Feb 17, 2018 at 5:01

jack gallerdude galler

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2 Comments

Shashank Singh Over a year ago

He wants to display a complete column and not a single element

jack gallerdude galler Over a year ago

for i in range(len(list)): print list[0][i] for the first column

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