Filter dates in a dictionary - python

Question

I have a dictionary like this:

> { "Country1": {"time": [1/22/20, 1/23/20...], "cases":[0,10,20,...]},
> "Country2": {"time": [1/22/20, 1/23/20...], "cases":[0,10,20,...]},
> .... }

I want to drop the dates higher than a given date and their respective cases. I've tried with this, but it fails because of IndexError: list index out of range. How would yo do it?

for i in (range(len(Country_Region))):
    for j in (range(len(Countries_Dict[i][Country_Region[i]]['time']))):
        if datetime.strptime(Countries_Dict[i][Country_Region[i]]['time'][j], '%m/%d/%y')  > datetime.strptime(date, '%m-%d-%y'):
            Countries_Dict[i][Country_Region[i]]['time'].pop(j)
            Countries_Dict[i][Country_Region[i]]['cases'].pop(j)

Dates are in string format, and the desired output is the same dictionary as before without the dates higher than a given date and their respective cases.

Those times will become floats, for example `1/22/20` -> `0.0022727272727272726`. They're supposed to be strings, aren't they? — wjandrea, Apr 16 '21 at 19:10
Related: [Strange result when removing item from a list while iterating over it](https://stackoverflow.com/q/6260089/4518341) — wjandrea, Apr 16 '21 at 19:12
It would help if you provided all the details, meaning some complete, valid example input, and the desired output, sort of like a [mre]. BTW, welcome to SO! Check out the [tour], and [ask] if you want tips. — wjandrea, Apr 16 '21 at 19:13

Hrishikesh · Answer 1 · 2021-04-17T12:52:10.750

Your IndexError is likely a fault of inconsistent data, with time and cases having different lengths.

You can use zip to bunch them together clipping at length of the smaller list.

data = {
    'Country1': {
        'time': ['1/22/20', '1/23/20', '1/24/20', '1/25/20'],
        'cases': [0, 10, 20, 30, 40]   # Inconsistent data
    },
    'Country2': {
        'time': ['1/22/20', '1/23/20', '1/24/20', '1/25/20'],
        'cases': [0, 10, 20, 30]
    }
}

threshold_date = '1/23/20'


def parse_date(date):
    return datetime.strptime(date, '%m/%d/%y')


for country, country_data in data.items():
    pre_threshold = [
        (time, case)
        for time, case in zip(country_data['time'], country_data['cases'])
        if parse_date(time) <= parse_date(threshold_date)
    ]
    country_data['time'] = [t for t, c in pre_threshold]
    country_data['cases'] = [c for t, c in pre_threshold]

This will result in,

{'Country1': {'time': ['1/22/20', '1/23/20'], 'cases': [0, 10]},
 'Country2': {'time': ['1/22/20', '1/23/20'], 'cases': [0, 10]}}

Notice that the first list had 4 vs 5 entries in time and cases but it didn't matter.

This is creating a new list, the efficiency of this code can be improved, but I've kept it so for the readability. You can choose to do so based on your need.

Filter dates in a dictionary - python

1 Answers1