Replacing values in a Python list/dictionary?

Question

Ok, I am trying to filter a list/dictionary passed to me and "clean" it up a bit, as there are certain values in it that I need to get rid of.

So, if it's looking like this:

"records": [{"key1": "AAA", "key2": "BBB", "key3": "CCC", "key4": "AAA"...}]

How would I quickly and easily run through it all and replace all values of "AAA" with something like "XXX"?

Focus is on speed and resources, as these may be long lists and I don't want this process to consume too much time.

score 28 · Accepted Answer · answered Jul 02 '09 at 20:40

28

DATA = {"records": [{"key1": "AAA", "key2": "BBB", "key3": "CCC", "key4": "AAA"}]}

for name, datalist in DATA.iteritems():  # Or items() in Python 3.x
    for datadict in datalist:
        for key, value in datadict.items():
            if value == "AAA":
                datadict[key] = "XXX"

print (DATA)
# Prints {'records': [{'key3': 'CCC', 'key2': 'BBB', 'key1': 'XXX', 'key4': 'XXX'}]}

answered Jul 02 '09 at 20:40

RichieHindle

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Yep, that worked like a charm. I was missing one of the outer loops and getting list/items() error... thank you! – Crazy Serb Jul 02 '09 at 20:55

score 11 · Answer 2 · answered Jul 02 '09 at 20:38

11

dic = root['records'][0]
for i, j in dic.items():       # use iteritems in py2k
    if j == 'AAA':
        dic[i] = 'xxx'

answered Jul 02 '09 at 20:38

SilentGhost

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score 0 · Answer 3 · answered Feb 01 '21 at 07:50

As far as I concerned, using if/else in a dictionary comprehension is much faster than the above answers. In the following, I have provided a generic example for your use case:

DATA = {"records_0": [{"key1": "AAA", "key2": "BBB", "key3": "CCC", "key4": "AAA"},
                      {"key1": "AAA", "key2": "BBB", "key3": "CCC", "key4": "AAA"}],
        "records_1": [{"key1": "AAA", "key2": "BBB", "key3": "CCC", "key4": "AAA"}]}

Replaced_DATA = {k:[
{k_0:v_0 if v_0!='AAA' else 'XXX' for k_0,v_0 in v_.items()} for v_ in v] for k,v in DATA.items()}

Here is the output:

Replaced_DATA
Out[1]. {'records_0': [{'key1': 'XXX', 'key2': 'BBB', 'key3': 'CCC', 'key4': 'XXX'}, 
                       {'key1': 'XXX', 'key2': 'BBB', 'key3': 'CCC', 'key4': 'XXX'}],
         'records_1': [{'key1': 'XXX', 'key2': 'BBB', 'key3': 'CCC', 'key4': 'XXX'}]}

Replacing values in a Python list/dictionary?

3 Answers3

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