Iterating over a 2 dimensional python list

Question

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

User · Answer

Ref  zip built-in function  zip   in conjunction with the   operator can be used to unzip a list  unzip lst   zip  mylist  for i in unzip lst      for j in i          print j

User · Answer

Use zip and itertools chain  Something like    gt  gt  gt  from itertools import chain  gt  gt  gt  l   chain from iterable zip  l    lt itertools chain object at 0x104612610 gt   gt  gt  gt  list l    0 0    1 0    2 0    0 1    1 1    2 1

User · Answer

This is the correct way    gt  gt  gt  x       0 0    0 1      1 0    1 1      2 0    2 1      gt  gt  gt  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  gt  gt  gt

User · Answer

gt  gt  gt  mylist       s  s   i j  for j in range columns   for i in range rows    gt  gt  gt  mylist    0 0    0 1    0 2      1 0    1 1    1 2      2 0    2 1    2 2     gt  gt  gt  zip  mylist     0 0    1 0    2 0      0 1    1 1    2 1      0 2    1 2    2 2     gt  gt  gt  sum zip  mylist        0 0    1 0    2 0    0 1    1 1    2 1    0 2    1 2    2 2

User · Answer

zip will transpose the list  after that you can concatenate the outputs   In  3   zip      0 0    0 1      1 0    1 1      2 0    2 1      Out 3      0 0    1 0    2 0      0 1    1 1    2 1

User · Answer

same way you did the fill in  but reverse the indexes    gt  gt  gt  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  gt  gt  gt

User · Answer

gt  gt  gt   el 0  if i  lt  len mylist  else el 1  for i el in enumerate mylist   mylist     0 0    1 0    2 0    0 1    1 1    2 1

[python] Iterating over a 2 dimensional python list

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