Iterating over a 2 dimensional python list

48

I have created a 2 dimension array like:

rows =3
columns= 2
mylist = [[0 for x in range(columns)] for x in range(rows)]
for i in range(rows):
    for j in range(columns):
        mylist[i][j] = '%s,%s'%(i,j)
print mylist

Printing this list gives an output:

[  ['0,0', '0,1'], ['1,0', '1,1'], ['2,0', '2,1']   ]

where each list item is a string of the format 'row,column'

Now given this list, i want to iterate through it in the order:

'0,0'
'1,0'
'2,0'
'0,1'
'1,1'
'2,1'

that is iterate through 1st column then 2nd column and so on. How do i do it with a loop ?

This Question pertains to pure python list while the question which is marked as same pertains to numpy arrays. They are clearly different

This question is tagged with python loops multidimensional-array

~ Asked on 2013-05-14 16:49:21

The Best Answer is


111

same way you did the fill in, but reverse the indexes:

>>> for j in range(columns):
...     for i in range(rows):
...        print mylist[i][j],
... 
0,0 1,0 2,0 0,1 1,1 2,1
>>> 

~ Answered on 2013-05-14 16:58:12


84

This is the correct way.

>>> x = [ ['0,0', '0,1'], ['1,0', '1,1'], ['2,0', '2,1'] ]
>>> for i in range(len(x)):
        for j in range(len(x[i])):
                print(x[i][j])


0,0
0,1
1,0
1,1
2,0
2,1
>>> 

~ Answered on 2013-05-14 16:57:03


Most Viewed Questions: