Create a compress function in Python?

I need to create a function called compress that compresses a string by replacing any repeated letters with a letter and number. My function should return the shortened version of the string. I’ve been able to count the first character but not any others.

Ex:

>>> compress("ddaaaff")
'd2a3f2'


 def compress(s):
     count=0

     for i in range(0,len(s)):
         if s[i] == s[i-1]:
             count += 1
         c = s.count(s[i])

     return str(s[i]) + str(c)

Answer

Here is a short python implementation of a compression function:

def compress(string):

    res = ""

    count = 1

    #Add in first character
    res += string[0]

    #Iterate through loop, skipping last one
    for i 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 one
    if(count > 1):
        res += str(count)
    return res

Here are a few examples:

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