Recursively replace characters in a dictionary

Question

How do I change all dots . to underscores (in the dict\'s keys), given an arbitrarily nested dictionary?

What I tried is write two loops, b

Answer 1

Assuming . is only present in keys and all the dictionary's contents are primitive literals, the really cheap way would be to use str() or repr(), do the replacement, then ast.literal_eval() to get it back:

d ={
    "brown.muffins": 5,
    "green.pear": 4,
    "delicious_apples": {
        "green.apples": 2
    } # correct brace
}

Result:

>>> import ast
>>> ast.literal_eval(repr(d).replace('.','_'))
{'delicious_apples': {'green_apples': 2}, 'green_pear': 4, 'brown_muffins': 5}

If the dictionary has . outside of keys, we can replace more carefully by using a regular expression to look for strings like 'ke.y': and replace only those bits:

>>> import re
>>> ast.literal_eval(re.sub(r"'(.*?)':", lambda x: x.group(0).replace('.','_'), repr(d)))
{'delicious_apples': {'green_apples': 2}, 'green_pear': 4, 'brown_muffins': 5}

If your dictionary is very complex, with '.' in values and dictionary-like strings and so on, use a real recursive approach. Like I said at the start, though, this is the cheap way.