compression - Create a compress function in Python? -

i need create function called compress compresses string replacing repeated letters letter , number. function should return shortened version of string. i've been able count first character not others.

ex:

>>> compress("ddaaaff") 'd2a3f2'    def compress(s):      count=0       in range(0,len(s)):          if s[i] == s[i-1]:              count += 1          c = s.count(s[i])       return str(s[i]) + str(c) 

here short python implementation of compression function:

def compress(string):      res = ""      count = 1      #add in first character     res += string[0]      #iterate through loop, skipping last 1     in range(len(string)-1):         if(string[i] == string[i+1]):             count+=1         else:             if(count > 1):                 #ignore if no repeats                 res += str(count)             res += string[i+1]             count = 1     #print last 1     if(count > 1):         res += str(count)     return res 

here few examples:

>>> compress("ddaaaff") 'd2a3f2' >>> compress("daaaafffyy") 'da4f3y2' >>> compress("mississippi") 'mis2is2ip2i'