Compare 2 lists consisting of dictionaries by key python-CodePudding

there are 2 lists of dictionaries with the same keys, for example:

old = [{'key1': 'AAA', 'key2': 'value2', 'key3': 'value3'},{'key1': 'BBB', 'key2': 'value4', 'key3': 'value5'},{'key1': 'CCC', 'key2': 'value4', 'key3': 'value5'}]

new = [{'key1': 'BBB', 'key2': 'value2', 'key3': 'value3'},{'key1': 'CCC', 'key2': 'value4', 'key3': 'value1'}]

The task is to get old[0] ({'key1': AAA, ...}) via the key 'key1'.

Tried the method below, but if the length of the lists are different, it does not work:

for x in old:
    for y in new:
        if x['key1'] in y['key1']:
            old.remove(x)

CodePudding user response：

Use the nested loop the other way round:

for y in new:
    for x in old:
        if x['key1'] == y['key1']:
            old.remove(x)
print(old)

which produces:

[{'key1': 'AAA', 'key2': 'value2', 'key3': 'value3'}]