Print a list of space-separated elements in Python 3

Question

I have a list L of elements  say natural numbers   I want to print them in one line with a single space as a separator   But I don t want a space after the last element of the list  or before the first    In Python 2  this can easily be done with the following code   The implementation of the print statement  mysteriously  I must confess  avoids to print an extra space before the newline   L    1  2  3  4  5  for x in L      print x  print   However  in Python 3 it seems that the  supposedly  equivalent code using the print function produces a space after the last number   L    1  2  3  4  5  for x in L      print x  end      print     Of course there are easy answers to my question   I know I can use string concatenation   L    1  2  3  4  5  print     join str x  for x in L     This is a quite good  solution  but compared to the Python 2 code I find it counter-intuitive and definitely slower   Also  I know I can choose whether to print a space or not myself  like   L    1  2  3  4  5  for i  x in enumerate L       print     if i gt 0 else     x  sep     end     print     but again this is worse than what I had in Python 2   So  my question is  am I missing something in Python 3   Is the behavior I m looking for supported by the print function

User · Answer

Although the accepted answer is absolutely clear, I just wanted to check efficiency in terms of time.

The best way is to print joined string of numbers converted to strings.

print(" ".join(list(map(str,l))))

Note that I used map instead of loop. I wrote a little code of all 4 different ways to compare time:

import time as t

a, b = 10, 210000
l = list(range(a, b))
tic = t.time()
for i in l:
    print(i, end=" ")

print()
tac = t.time()
t1 = (tac - tic) * 1000
print(*l)
toe = t.time()
t2 = (toe - tac) * 1000
print(" ".join([str(i) for i in l]))
joe = t.time()
t3 = (joe - toe) * 1000
print(" ".join(list(map(str, l))))
toy = t.time()
t4 = (toy - joe) * 1000
print("Time",t1,t2,t3,t4)

Result:

Time 74344.76 71790.83 196.99 153.99

The output was quite surprising to me. Huge difference of time in cases of 'loop method' and 'joined-string method'.

Conclusion: Do not use loops for printing list if size is too large( in order of 10**5 or more).

User · Answer

You can apply the list as separate arguments   print  L    and let print   take care of converting each element to a string  You can  as always  control the separator by setting the sep keyword argument    gt  gt  gt  L    1  2  3  4  5   gt  gt  gt  print  L  1 2 3 4 5  gt  gt  gt  print  L  sep       1  2  3  4  5  gt  gt  gt  print  L  sep   - gt     1 - gt  2 - gt  3 - gt  4 - gt  5   Unless you need the joined string for something else  this is the easiest method  Otherwise  use str join     joined string       join  str v  for v in L   print joined string    do other things with joined string   Note that this requires manual conversion to strings for any non-string values in L

User · Answer

Joining elements in a list space separated   word     test    crust    must    fest   word reverse   joined string      for w in word     joined string   w   joined string       print joined string rstrim

User · Answer

list    1  2  3  4  5  for i in list 0 -1       print i  end       print list -1     do for loops really take that much longer to run   was trying to make something that printed all str values in a list separated by commas  inserting  and  before the last entry and came up with this   spam     apples    bananas    tofu    cats   for i in spam 0 -1       print i  end       print  and     spam -1

[python] Print a list of space-separated elements in Python 3

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