Joining iterables
Last Updated: February 3, 2018 12:20 PM UTC
Last edited by:
Joseph <joseph@josephbanks.me>
Initial Commit
THIS IS FAKE DEMO DATA

If you want to display a list (or some other iterable), you can write: 

colors = ['red', 'green', 'blue', 'yellow']
output = ""
separator = ", "
for color in colors:
    output += color + separator
print(output)
# Prints 'red, green, blue, yellow, '
However, the separator is still added to the last element, and it is relatively slow.

A better solution is to use str.join. 

colors = ['red', 'green', 'blue', 'yellow']
separator = ", "
print(separator.join(colors))
# Prints 'red, green, blue, yellow'
An important thing to note is that you can only str.join strings. For a list of ints, you must convert each element to a string before joining. 
integers = [1, 3, 6, 10, 15]
print(", ".join(str(e) for e in integers))
# Prints '1, 3, 6, 10, 15'