Compare two dict and change keys in second if keys exists as sub-value in first

Question

Need help remapping the keys for d2 if they match the value for id in d1. In case there are keys that are unmatched, drop them.

d1={'A':{'id':'a'},'B':{'id':'b'}}
d2={'a':1,'b':2, 'c':3}

Expected output:

{'A': 1, 'B': 2}

Answer 1

You could traverse d1 and use d2 as a lookup to modify values:

for k, d in d1.items():
    d1[k] = d2.get(d['id'])

If you want to modify df2 instead, you could use a dict comprehension:

d2 = {k: d2.get(d['id']) for k, d in d1.items()}

or use two loops (once to modify values of keys that exist in df1 and once to remove any keys that don't exist in df1):

for k, d in d1.items():
    d2[k] = d2.pop(d['id'])
for k in list(d2.keys() - d1.keys()):
    d2.pop(k)

Output:

{'A': 123, 'B': 123}