Associate letters with its value and sort output in python

Question

Please help on this. I have an input like this:

 a = """A|9578
 C|547
 A|459
 B|612
 D|53
 B|6345
 A|957498
 C|2910"""

I want to print in sorted way the numbers related with each letter like this:

 A_0|459
 A_1|957498
 A_2|9578
 C_0|2910
 C_1|547
 B_0|612
 B_1|6345
 D_0|53

So far I was able to store in array b the letters and numbers, but I'm stuck when I try to create dictionary-like array to join a single letter with its values, I get this error.

 b = [i.split('|') for i in a.split('\n')]
 c = dict()
 d = [c[i].append(j) for i,j in b]
 >>> d = [c[i].append(j) for i,j in b]
 Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "<stdin>", line 1, in <listcomp>
 TypeError: list indices must be integers or slices, not str

I'm working on python 3.6 just in case. Thanks in advance.

Answer 1

We'll split the string into pairs, sort those pairs, then use groupby and enumerate to come up with the indices.

from itertools import groupby
from operator import itemgetter

def process(a):
    pairs = sorted(x.split('|') for x in a.split())
    groups = groupby(pairs, key=itemgetter(0))
    for _, g in groups:
        for index, (letter, number) in enumerate(g):
            yield '{}_{}|{}'.format(letter, index, number)

for i in process(a): print(i)

gives us

A_0|459
A_1|957498
A_2|9578
B_0|612
B_1|6345
C_0|2910
C_1|547
D_0|53