First of all, bravo to snippsat for a very elegant solution. I have never seen string splicing like that.
Now, how to remove the spaces and symbols? Well there is the easy inefficient way and the efficient but more difficult way.
The easy but inefficient way would be to loop through each character in the string and test if it is a space, tab, period, comma, etc. If so, then move on to the next character. If it is not one of those, then write it to a temporary string. Then test the temporary string to see if it is a palindrome and return true or false.
The problem with this method is that you're going to have a lot of if statements that you'll need to maintain. You would have to have an if statement for every symbol and non printable character on your keyboard...not to mention international symbols too. You would also run every character through a ton of tests that most likely wont apply so your code will be less efficient and more difficult to maintain. On the other hand, if this is an assignment for an entry level class this is probably all that is expected of you at this point.
The more efficient way of doing it would be to test each character against a regular expression of characters that you're interested in. If the character is in the range of a-z then copy it to a temporary string. If not, then pass on to the next character. Now you only have to maintain one if statement instead of a quadrillion. It will be more effective because it looks for a list of known acceptable characters rather than trying to list every character you're not interested in, and you will only perform one test on each character which makes your code more efficient.
mystring = 'A man, a plan, a canal, panama.'
# first, establish a temporary string and strip out the unwanted
# characters
tempstring = ""
for char in mystring.lower():
if re.match("[a-z]", char):
tempstring += char
# then use the techniques described above to test for palindrome.
return tempstring == tempstring[::-1]
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