String split with default delimiter vs user defined delimiter

Question

I tried a simple example with string split, but get some unexpected behavior. Here is the sample code:

def split_string(source,splitlist):
    for delim in splitlist:
        source = source.replace(delim, ' ')
    return source.split(' ')

out = split_string("This is a test-of the,string separation-code!", " ,!-")
print out
>>> ['This', 'is', 'a', 'test', 'of', 'the', 'string', 'separation', 'code', '']

As you can see, I got an extra empty string at the end of the list when I use space as delimiter argument for split() function. However, if I don't pass in any argument for split() function, I got no empty string at the end of the output list.

From what I read in python docs, they said the default argument for split() is space. So, why when I explicitly pass in a ' ' as delimiter, it creates an empty string at the end of the output list?

Answer 1

The docs:

If sep is not specified or is None, a different splitting algorithm is applied: runs of consecutive whitespace are regarded as a single separator, and the result will contain no empty strings at the start or end if the string has leading or trailing whitespace.