Codon table in Python dict

gistfile1.txt

codontab = {
    'TCA': 'S',    # Serina
    'TCC': 'S',    # Serina
    'TCG': 'S',    # Serina
    'TCT': 'S',    # Serina
    'TTC': 'F',    # Fenilalanina
    'TTT': 'F',    # Fenilalanina
    'TTA': 'L',    # Leucina
    'TTG': 'L',    # Leucina
    'TAC': 'Y',    # Tirosina
    'TAT': 'Y',    # Tirosina
    'TAA': '*',    # Stop
    'TAG': '*',    # Stop
    'TGC': 'C',    # Cisteina
    'TGT': 'C',    # Cisteina
    'TGA': '*',    # Stop
    'TGG': 'W',    # Triptofano
    'CTA': 'L',    # Leucina
    'CTC': 'L',    # Leucina
    'CTG': 'L',    # Leucina
    'CTT': 'L',    # Leucina
    'CCA': 'P',    # Prolina
    'CCC': 'P',    # Prolina
    'CCG': 'P',    # Prolina
    'CCT': 'P',    # Prolina
    'CAC': 'H',    # Histidina
    'CAT': 'H',    # Histidina
    'CAA': 'Q',    # Glutamina
    'CAG': 'Q',    # Glutamina
    'CGA': 'R',    # Arginina
    'CGC': 'R',    # Arginina
    'CGG': 'R',    # Arginina
    'CGT': 'R',    # Arginina
    'ATA': 'I',    # Isoleucina
    'ATC': 'I',    # Isoleucina
    'ATT': 'I',    # Isoleucina
    'ATG': 'M',    # Methionina
    'ACA': 'T',    # Treonina
    'ACC': 'T',    # Treonina
    'ACG': 'T',    # Treonina
    'ACT': 'T',    # Treonina
    'AAC': 'N',    # Asparagina
    'AAT': 'N',    # Asparagina
    'AAA': 'K',    # Lisina
    'AAG': 'K',    # Lisina
    'AGC': 'S',    # Serina
    'AGT': 'S',    # Serina
    'AGA': 'R',    # Arginina
    'AGG': 'R',    # Arginina
    'GTA': 'V',    # Valina
    'GTC': 'V',    # Valina
    'GTG': 'V',    # Valina
    'GTT': 'V',    # Valina
    'GCA': 'A',    # Alanina
    'GCC': 'A',    # Alanina
    'GCG': 'A',    # Alanina
    'GCT': 'A',    # Alanina
    'GAC': 'D',    # Acido Aspartico
    'GAT': 'D',    # Acido Aspartico
    'GAA': 'E',    # Acido Glutamico
    'GAG': 'E',    # Acido Glutamico
    'GGA': 'G',    # Glicina
    'GGC': 'G',    # Glicina
    'GGG': 'G',    # Glicina
    'GGT': 'G'     # Glicina
}

And the reverse table mapping amino acids to a list of codons

from collections import defaultdict

aminotab = defaultdict(list)
for codon, aa in codontab.items():
    aminotab[aa].append(codon)

The contents of the amino table

{'S': ['TCT', 'TCC', 'TCA', 'TCG', 'AGT', 'AGC'], 'L': ['TTA', 'TTG', 'CTT', 'CTC', 'CTA', 'CTG'], 'C': ['TGT', 'TGC'], 'W': ['TGG'], 'E': ['GAA', 'GAG'], 'D': ['GAT', 'GAC'], 'P': ['CCT', 'CCC', 'CCA', 'CCG'], 'V': ['GTT', 'GTC', 'GTA', 'GTG'], 'N': ['AAT', 'AAC'], 'M': ['ATG'], 'K': ['AAA', 'AAG'], 'Y': ['TAT', 'TAC'], 'I': ['ATT', 'ATC', 'ATA'], 'Q': ['CAA', 'CAG'], 'F': ['TTT', 'TTC'], 'R': ['CGT', 'CGC', 'CGA', 'CGG', 'AGA', 'AGG'], 'T': ['ACT', 'ACC', 'ACA', 'ACG'], '*': ['TAA', 'TAG', 'TGA'], 'A': ['GCT', 'GCC', 'GCA', 'GCG'], 'G': ['GGT', 'GGC', 'GGA', 'GGG'], 'H': ['CAT', 'CAC']}

Interesting, not only the defaultdict constructor, but the form to link a list of codons to every aa. It also could be done without resorting to that python library. In fact it returns some noise:
defaultdict(<class 'list'>, {'S': ['TCA',..

with:

aminotab = {}
for codon, aa in codontab.items():
    if aa in aminotab:
        aminotab[aa].append(codon)
    else:
        aminotab[aa] = [codon]

print(aminotab)

wich I suspect is faster, more independent (and easier to remember) and doesn't yield artefacts.

Thanks!