How to Determine how similar two strings are (until a certain point)

I have a list of strings ['49275', '49287', '69674', '43924']

I want to see how similar they are to a certain value (lets say '49375' BUT once there is a difference, everything past the difference needs to be counted as NOT similar (even if they are)

So '49375' and '49275' should have a similarity of 0.4 NOT 0.8

I tried the code below but I am getting stumped and there must be a better way.

l = ['49275', '49287', '69674', '43924']
x = '49375'

listy = []
for i in l:
  for n in range(len(x)):
    if x[n] == i[0][n]:
      listy.append((n+1)/len(x))
    if x[n] != i[0][n]:
      break

I would like the output to be a list of similarity numbers, i.e: [0.4, 0.4, 0, 0.2]

Thank You!

Solution

You were close. You just want to append to listy at the point where the characters do not match (i.e. before the break), or if the loop completes without a break then append 1.0.

Note also that you want i[n] rather than i[0][n] - the i[0][n] was giving you an IndexError because you were taking the first character and then trying to take character n from that.

l = ['49275', '49287', '69674', '43924']
x = '49375'

listy = []
for i in l:
    for n in range(len(x)):
        if x[n] != i[n]:
            listy.append(n / len(x))
            break
    else:
        listy.append(1.)

print(listy)