Python : Generate nested dict

Question

I have the following dict :

dic = {'seq1': '(prot1_val1, prot1_val10, prot2_val2, prot3_val3)',
        'seq2': '(prot1_val5)',
        'seq3': '(prot2_val2,prot4_val7)' 
       }

and I would like to obtain this :

d = { 'prot1': {'seq1': ['val1', 'val10'], 'seq2': ['val5']},
      'prot2': {'seq1': ['val2'], 'seq3': ['val2']},
      'prot3': {'seq1': ['val3']},
      'prot4': {'seq3': ['val7']}
    }

I have tried by doing like this :

d = {}
for key, value in dico.items():
    t = tuple([tuple(i.split("_")) for i in re.split(',',re.sub('[()]','',value))])
    for prot,val in t:
        d.setdefault(prot, {})[key].apppend(val)
print(d)

But if get a KeyError. How can I resolve this?

Suggestion: do *one* operation per line and see in which line the error is. — mkrieger1, Nov 30 '21 at 16:42
See also: [How to step through Python code to help debug issues?](https://stackoverflow.com/questions/4929251/how-to-step-through-python-code-to-help-debug-issues) — mkrieger1, Nov 30 '21 at 16:43
This code `d.setdefault(prot, {})[key]` is obviously going to fail with KeyError in the default case because the default value is an empty dict and an empty dict has no keys. — jarmod, Nov 30 '21 at 16:52

score 0 · Accepted Answer · answered Nov 30 '21 at 16:52

Try:

d = dict()
for seq, string in dico.items():
    pairs = [(x.split("_")[0].strip(), x.split("_")[1].strip()) for x in string.strip("()").split(",")]
    for pro, val in pairs:
        if pro not in d:
            d[pro] = dict()
        if seq not in d[pro]:
            d[pro][seq] = list()
        d[pro][seq].append(val)
        
>>> d
{'prot1': {'seq1': ['val1', 'val10'], 'seq2': ['val5']},
 'prot2': {'seq1': ['val2'], 'seq3': ['val2']},
 'prot3': {'seq1': ['val3']},
 'prot4': {'seq3': ['val7']}}

Python : Generate nested dict

1 Answers1