[Python] What would be the best way to remove everything but letters?

[RectangularBox]

For a programming assignment I am supposed to write a function that removes everything from a string except letters. My current method has more that a few flaws, and I was wondering if there was a better way to do it. Here is the current function:

 

def remove_extras(string):

    return string.translate(None,' ?.!/;:=-)(*&^%$#@`~><\|}{,_+"'+"'")

 

Currently it just translates all symbols to strings, but this is not 100% effective in testing.

[boparai]

you would probably be better off using simple regex. Here :
 
 

import redef only_alpha(text):    regex = re.compile(r'[A-Za-z]+')    ans = "".join(regex.findall(text))    return ans

it should probably do it if you have any confusion about the regex just ask i'll explain it to you

[RectangularBox]

    regex = re.compile(r'[A-Za-z]+')    ans = "".join(regex.findall(text))

it should probably do it if you have any confusion about the regex just ask i'll explain it to you

What are those 2 lines doing? I don't really know anything about regex.

[boparai]

the first line is compiling a regular for later use.

 

I'll explain piece by piece :

 

r' ' : it for python raw strings for unconflicting regex

[ ] : are selectors to specify which characters and/or range of characters to find

A-Z: specify all upper case letters and a-z all lower  case letters

+ : is a greedy meta-character which tells the regex engine to find 1 or more characters which match earlier criteria

 

lets  see an example :http://docs.python.org/2/howto/regex.html

 

string = 'i_am doing**it ^&wrong 1234'

 

and we're using findall so it will well find all parts of the string that match our regex and return a list

 

list = ['i','am','doing','it','wrong']

 

and then join everything in the list with the blank string and return "iamdoingitwrong"

 

Although it is a little bit complicated since you don't about regex much but it is a lot more safer and short and frankly it will far more easy when you learn about regex

 

you can learn more about regex here : http://docs.python.org/2/howto/regex.html

[fizzlesticks]

Or if you prefer the not so regex way

import stringsomeString = 'jkKALjd(@)(EJ)DJQ(@JD(Q*JD( NDM(*@QJD(Q*JD(*QJ(_@*J('fixedString = ''.join([x for x in someString if x in (string.ascii_lowercase + string.ascii_uppercase)])

[boparai]

 

Or if you prefer the not so regex way

import stringsomeString = 'jkKALjd(@)(EJ)DJQ(@JD(Q*JD( NDM(*@QJD(Q*JD(*QJ(_@*J('fixedString = ''.join([x for x in someString if x in (string.ascii_lowercase + string.ascii_uppercase)])

 

Actually its simply better.