In Python is there an elegant way to print a list in a custom format without explicit looping

Question

I know you can do   print str myList    to get     1  2  3    and you can do  i   0 for entry in myList    print str i         entry   i    1   to get    0  1   1  2   2  3       But is there a way similar to the first to get a result similar to the last   With my limited knowledge of Python  and some help from the documentation   my best is   print   n  join  str n           str entry  for  n  entry  in zip range 0 len myList    myList      It s not much less verbose  but at least I get a custom string in one  compound  statement  Can you do better

User · Accepted Answer

gt  gt  gt  lst    1  2  3   gt  gt  gt  print   n  join          format  k  for k in enumerate lst    0  1 1  2 2  3   Note  you just need to understand that list comprehension or iterating over a generator expression is explicit looping

User · Answer

In python 3s print function   lst    1  2  3  print  My list     lst  sep   n-      Output   My list  - 1 - 2 - 3   Con  The sep must be a string  so you can t modify it based on which element you re printing  And you need a kind of header to do this  above it was  My list      Pro  You don t have to join   a list into a string object  which might be advantageous for larger lists  And the whole thing is quite concise and readable

User · Answer

gt  gt  gt  from itertools import starmap   gt  gt  gt  lst    1  2  3   gt  gt  gt  print   n  join starmap          format  enumerate lst     0  1 1  2 2  3   This uses itertools starmap  which is like map  except it  s the argument into the function  The function in this case is          format   I would prefer the comprehension of SilentGhost  but starmap is a nice function to know about

User · Answer

l    1  2  3  print   n  join    i   s     n  l n   for n in xrange len l

User · Answer

Take a look on pprint  The pprint module provides a capability to    pretty-print    arbitrary Python data structures in a form which can be used as input to the interpreter  If the formatted structures include objects which are not fundamental Python types  the representation may not be loadable  This may be the case if objects such as files  sockets or classes are included  as well as many other objects which are not representable as Python literals    gt  gt  gt  import pprint  gt  gt  gt  stuff     spam    eggs    lumberjack    knights    ni    gt  gt  gt  stuff insert 0  stuff      gt  gt  gt  pp   pprint PrettyPrinter indent 4   gt  gt  gt  pp pprint stuff        spam    eggs    lumberjack    knights    ni         spam        eggs        lumberjack        knights        ni    gt  gt  gt  pp   pprint PrettyPrinter width 41  compact True   gt  gt  gt  pp pprint stuff     spam    eggs    lumberjack      knights    ni      spam    eggs    lumberjack    knights     ni    gt  gt  gt  tup     spam     eggs     lumberjack     knights     ni     dead         parrot     fresh fruit            gt  gt  gt  pp   pprint PrettyPrinter depth 6   gt  gt  gt  pp pprint tup    spam     eggs     lumberjack     knights     ni     dead

User · Answer

from time import clock from random import sample  n   500 myList   sample xrange 10000  n   print myList  A B C D                for i in xrange 100       t0   clock       ecr      n  join          format  k  for k in enumerate myList         A append clock  -t0       t0   clock       ecr     n  join str n           str entry  for  n  entry  in zip range 0 len myList    myList       B append clock  -t0       t0   clock       ecr     n  join map lambda x    s   s    x  enumerate myList        C append clock  -t0       t0   clock       ecr     n  join   s   s    x for x in enumerate myList       D append clock  -t0   print   n  join   t1     str min A             1     format min A  min D                      t2     str min B             1     format min B  min D                      t3     str min C             1     format min C  min D                      t4     str min D             1     format min D  min D       For n 500   150 8   142 7   110 8   100 0     For n 5000   153 5   176 2   109 7   100 0     Oh  I see now  only the solution 3 with map   fits with the title of the question

User · Answer

Another    gt  gt  gt  lst  10 11 12   gt  gt  gt  fmt   i   i   gt  gt  gt  for d in enumerate lst          print fmt d       0  10 1  11 2  12   Yet another form    gt  gt  gt  for i j in enumerate lst   print   i   i   i j    That method is nice since the individual elements in tuples produced by enumerate can be modified such as     gt  gt  gt  for i j in enumerate  3 4 5  1   print   i  i   i    i j i  j       1 3  1  2 4  16  3 5  243    Of course  don t forget you can get a slice from this like so    gt  gt  gt  for i j in list enumerate lst   1 2   print   i   i   i j       1  11

User · Answer

Starting from this    gt  gt  gt  lst    1  2  3   gt  gt  gt  print   n  join          format  k  for k in enumerate lst    0  1 1  2 2  3   You can get rid of the join by passing  n as a separator to print   gt  gt  gt  print            format  k  for k in enumerate lst    sep   n   0  1 1  2 2  3   Now you see you could use map  but you ll need to change the format string  yuck     gt  gt  gt  print   map   0 0     0 1    format  enumerate lst     sep   n   0  1 1  2 2  3   or pass 2 sequences to map  A separate counter and no longer enumerate lst   gt  gt  gt  from itertools import count  gt  gt  gt  print   map          format  count    lst    sep   n   0  1 1  2 2  3

[python] In Python, is there an elegant way to print a list in a custom format without explicit looping?

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