CODEWITHSUNDEEP
pythonlistpython-3.xvariable-assignment
Ren
Ren

Reputation: 2946

How can I read inputs from user and create a 2-D List?

I have created a 2-dimensional array like:

>>> a = [[0 for col in range(3)] for row in range(3)]

then 

>>> for i in range(3):
...       for j in range(3):
...           a[i][j]=input()
...

1 2 3
4 5 6
7 8 9

but it doesn't success,python think '1 2 3' is one element,and how can I do that in above form?Thanks for any help.

Upvotes: 3

Views: 70

Answers (4)

Padraic Cunningham
Padraic Cunningham

Reputation: 180411

You can split and map to int in your first list comp, you don't need to create the list first, although bear in mind casting to int will make your program crash for invalid input:

a = [list(map(int,input().split())) for row in range(3)]

print(a)
[[1, 2, 3], [4, 5, 6], [7, 8, 9]]

Of course if you don't want ints just split on whitespace:

 a = [input().split() for row in range(3)]
 [['1', '2', '3'], ['4', '5', '6'], ['7', '8', '9']]

Upvotes: 1

thefourtheye
thefourtheye

Reputation: 239473

You don't have to create the list before-hand. You can directly create them in the list comprehension like this

>>> a = [[int(item) for item in input().split()] for row in range(3)]
1 2 3
4 5 6
7 8 9
>>> a
[[1, 2, 3], [4, 5, 6], [7, 8, 9]]

Here, whenever input is called, whatever we feed in will be read as a single string ('1 2 3') and we split the string on the whitespace characters (to get ['1', '2', '3']) and convert each of the split string to integer, with int function.

Upvotes: 3

ZdaR
ZdaR

Reputation: 22954

For taking space separated input you need to split the input text on " "

a=[[0 for col in range(3)] for row in range(3)]

for i in range(3):
    a[i][0], a[i][1], a[i][2] = map(int, raw_input().split())

print a

Upvotes: 1

Eugene Soldatov
Eugene Soldatov

Reputation: 10135

You can split values like this:

for i in range(3):
    a[i] = input().split(' ')

Upvotes: 1

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