Question

guys, I’m a programming newbie trying to improve the procedure bellow in a way that when I pass it this argument: split_string("After the flood ... all the colors came out."," .") it returns it:

['After', 'the', 'flood', 'all', 'the', 'colors', 'came', 'out']

and not this:

['After', 'the', 'flood', '', '', '', '', 'all', 'the', 'colors', 'came', 'out', ''] 

Any hint of how to do this? (I could just iterate again the list and delete the ” elements, but I wanted a more elegant solution)

This is the procedure:

def split_string(source, separatorList):
    splited = [source]
    for separator in splitlist:
        source = splited
        splited = []
        print 'separator= ', separator
        for sequence in source:
            print 'sequence = ', sequence
            if sequence not in splitlist and sequence != ' ':
                splited = splited + sequence.split(separator)            
    return splited

print split_string("This is a test-of the,string separation-code!", " ,!-")
print
print split_string("After  the flood   ...  all the colors came out."," .")

Answer 1

Let’s see where did the empty strings come from first, try to execute this in shell:

>>> 'After the'.split(' ')

result:

['After', '', 'the']

This was because when split method came to ' ' in the string, it find nothing but '' between two spaces.

So the solution is simple, just check the boolean value of every item get from .split(

def split_string(source, separatorList):
    splited = [source]
    for separator in separatorList:
        # if you want to exchange two variables, then write in one line can make the code more clear
        source, splited = splited, []
        for sequence in source:
            # there's no need to check `sequence` in advance, just split it
            # if sequence not in separatorList and sequence != ' ':
                # splited = splited + sequence.split(separator)

            # code to prevent appearance of `''` is here, do a if check in list comprehension.
            # `+=` is equivalent to `= splited +`
            splited += [i for i in sequence.split(separator) if i]
    return splited

More details about [i for i in a_list if i] see PEP 202