CODEWITHSUNDEEP
pythonpython-3.xlistfor-loopnested
NoobCoder
NoobCoder

Reputation: 675

Accessing dictionary inside Python List

I have a list which contains dictionaries like this:

json_obj = [[{'id': None},{'id': '5b98d01c0835f23f538cdcab'},{'id': '5b98d0440835f23f538cdcad'},{'id': '5b98d0ce0835f23f538cdcb9'}],[{'id': None},{'id': '5b98d01c0835f23f538cd'},{'id': '5b98d0440835f23f538cd'},{'id': '5b98d0ce0835f23f538cdc'}]]

I want it to store in list of lists like this:

y=[['None','5b98d01c0835f23f538cdcab','5b98d0440835f23f538cdcad','5b98d0ce0835f23f538cdcb9'],['None','5b98d01c0835f23f538cd','5b98d0440835f23f538cd','5b98d0ce0835f23f538cdc']]

For reading the id from the dictionary I tried 

for d in json_obj:
    print(d['id'])

But I see this error with the above code:

TypeError: list indices must be integers or slices, not str

Upvotes: 1

Views: 55

Answers (2)

jpp
jpp

Reputation: 164623

You have a nested list of lists. It sometimes helps to observe this visibly, note the nested [] syntax:

json_obj = [[{'id': None}, {'id': 'abc'}, {'id': 'def'}, {'id': 'ghi'}],
            [{'id': None}, {'id': 'jkl'}, {'id': 'mno'}, {'id': 'pqr'}]]

Your syntax would works for single list:

json_obj = [{'id': None}, {'id': 'abc'}, {'id': 'def'}, {'id': 'ghi'},
            {'id': None}, {'id': 'jkl'}, {'id': 'mno'}, {'id': 'pqr'}]

for d in json_obj:
    print(d['id'])

For nested lists, you can use itertools.chain.from_iterable from the standard library:

json_obj = [[{'id': None}, {'id': 'abc'}, {'id': 'def'}, {'id': 'ghi'}],
            [{'id': None}, {'id': 'jkl'}, {'id': 'mno'}, {'id': 'pqr'}]]

from itertools import chain

for d in chain.from_iterable(json_obj):
    print(d['id'])

Or, without an import you can use a nested for loop:

for L in json_obj:
    for d in L:
        print(d['id'])

Upvotes: 2

Rakesh
Rakesh

Reputation: 82765

Using a nested list comprehension.

json_obj = [[{'id': None},{'id': '5b98d01c0835f23f538cdcab'},{'id': '5b98d0440835f23f538cdcad'},{'id': '5b98d0ce0835f23f538cdcb9'}],[{'id': None},{'id': '5b98d01c0835f23f538cd'},{'id': '5b98d0440835f23f538cd'},{'id': '5b98d0ce0835f23f538cdc'}]]
print( [[j["id"] for j in i] for i in json_obj] )

or

for i in json_obj:
    for j in i:
        print(j["id"])

Output:

[[None, '5b98d01c0835f23f538cdcab', '5b98d0440835f23f538cdcad', '5b98d0ce0835f23f538cdcb9'], [None, '5b98d01c0835f23f538cd', '5b98d0440835f23f538cd', '5b98d0ce0835f23f538cdc']]

Upvotes: 0

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