How can I use str.join() instead of "+=" to join a list of strings with separator?

Question

I have some code which is essentially this:

data = ["some", "data", "lots", "of", "strings"]
separator = "."

output_string = ""
for datum in data:
    output_string += datum + separator

How can I do this with str.join() or a similar built-in function?

Answer 1

If the separator is a variable you can just use variable.join(iterable):

data = ["some", "data", "lots", "of", "strings"]
separator = "."


print(separator.join(data))
some.data.lots.of.strings

Answer 2

output_string = ".".join(data)

if you have integers or non-strings in data, then

output_string = ".".join( str(x) for x in data )