Python dictionary iteration

Question

I have a dictionary dict2 which I want to iter through and remove all entries that contain certain ID numbers in idlist. dict2[x] is a li

Answer 1

An approach using sets (Note that I needed to change your variables A, B, C, etc. to strings and the numbers in your idlist to actual integers; also this only works, if your IDs are unique and don't occur in other 'fields'):

#!/usr/bin/env python
# 2.6 <= python version < 3

original = {
    'G1' : [
        ['A', 123456, 'C', 'D'], 
        ['A', 654321, 'C', 'D'], 
        ['A', 456123, 'C', 'D'], 
        ['A', 321654, 'C', 'D'],
    ]
}

idlist = [123456, 456123, 321654]
idset = set(idlist)

filtered = dict()

for key, value in original.items():
    for quad in value:
        # decide membership on whether intersection is empty or not
        if not set(quad) & idset:
            try:
                filtered[key].append(quad)
            except KeyError:
                filtered[key] = quad

print filtered
# would print:
# {'G1': ['A', 654321, 'C', 'D']}

Answer 2

Try a cleaner version perhaps?

for k in dict2.keys():
    dict2[k] = [x for x in dict2[k] if x[1] not in idlist]
    if not dict2[k]:
        del dict2[k]