Print a list of space-separated elements

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>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?

Answer 1

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:

>>> L = [1, 2, 3, 4, 5] >>> print(*L) 1 2 3 4 5 >>> print(*L, sep=', ') 1, 2, 3, 4, 5 >>> print(*L, sep=' -> ') 1 -> 2 -> 3 -> 4 -> 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!