python filter nested dictionary keys of second nested dict key with function rule IN ONE LINER-CodePudding

I have a dictionary in this form:

example ={'2020_01': {'PM0001': 1088, 'CA00006': 33, 'X00002': 125, 'J00009': 119, 'A0000S': 524},
 '2020_02': {'F00067': 3, 'P00001': 1104, 'X00002': 98, 'J0009': 36, 'A0000S': 539},
 '2020_03': {'P00001': 1200, 'Z78800': 45,'X00000': 84,'NK0000': 4,'A0000S': 577,'V000000':11}}

I would like to extract a second dict including only values in the second dictionary nested which keys comply with a certain rule. this rule is given by a function.

def rule(string):
    # this is an hipythetical rule which in reality is way more complicated.
    if string.startswith("P") or string.startswith("X"):
        if string[1] == "0":
            return True
    return False

Using for loops I am able to perform the operation as follows:

new_dict={}
for date,ussage in example.items():
    new_sub_dict = {key:value for key,value in ussage.items() if rule(key)==True}
    new_dict[date] = new_sub_dict
new_dict

The question is if it is possible to rewrite that with one liner.

CodePudding user response：

Try:

new_dict = {
    k: {
        kk: vv
        for kk, vv in v.items()
        if kk.startswith(("P", "X")) and kk[1] == "0"
    }
    for k, v in example.items()
}

print(new_dict)

Prints:

{'2020_01': {'X00002': 125}, '2020_02': {'P00001': 1104, 'X00002': 98}, '2020_03': {'P00001': 1200, 'X00000': 84}}

EDIT: Thanks @KellyBundy to shorten the if-condition.

CodePudding user response：

try

new_dict={date:{key:value for key,value in example[date].items() if rule(key)} for date in example.keys()