Python过滤并从字典列表中创建字典

Question

I have list of dict

[{
    'bytesUsed': 79095,
    'servicePlan': '25MB',
    'smsUsed': 0,
    'source': 'Raw Usage',
    'timestamp': '2019-02-28T19:00:00-05:00'
}, {
    'bytesUsed': 310435,
    'servicePlan': '25MB',
    'smsUsed': 0,
    'source': 'Raw Usage',
    'timestamp': '2019-04-01T19:00:00-05:00'
}, {
    'bytesUsed': 286033,
    'servicePlan': '25MB',
    'smsUsed': 0,
    'source': 'Raw Usage',
    'timestamp': '2019-05-06T19:00:00-05:00'
}]

Which I want to filter out dict if timestamp field is not in the range (2019-02-11T19:00:00-05:00 - 2019-04-10T19:00:00-05:00) and create key:value map like

{'2019-02-28T19:00:00-05:00' : 79095, '2019-04-01T19:00:00-05:00' : 310435} 

Whats is the efficient way to do this ?

at present I am doing it for & if on each dict in list, which it taking time consuming.

Answer 1

I took at guess at what you're trying get. Unfortunately your expected output wasn't clear.

I'm always a fan of dateutil module.

from dateutil.parser import parse
dt1 = parse("2019-02-11T19:00:00-05:00")
dt2 = parse("2019-04-10T19:00:00-05:00")

newdl = []
for dic in dictlist:
    dt = parse(dic['timestamp'])
    if dt1 <= dt <= dt2:
        newdl.append({dic['timestamp'] : dic['bytesUsed']})
print(newdl)

output:

[{'2019-02-28T19:00:00-05:00': 79095}, {'2019-04-01T19:00:00-05:00': 310435}]

If you think you are going to use the datetimes again, I would make dt the key instead of the string; it will save you from having to parse the string again later.

Though I would be careful using dates of any kind (string or datetime) as dictionary keys unless you can guarantee they are always unique.

Answer 2

Try this,

from dateutil.parser import parse

start_dt = parse("2019-02-11T19:00:00-05:00")
end_dt = parse("2019-04-10T19:00:00-05:00")

arr = [
    {
        'bytesUsed': 79095,
        'servicePlan': '25MB',
        'smsUsed': 0,
        'source': 'Raw Usage',
        'timestamp': '2019-02-28T19:00:00-05:00'
    },
    {
        'bytesUsed': 310435,
        'servicePlan': '25MB',
        'smsUsed': 0,
        'source': 'Raw Usage',
        'timestamp': '2019-04-01T19:00:00-05:00'
    },
    {
        'bytesUsed': 286033,
        'servicePlan': '25MB',
        'smsUsed': 0,
        'source': 'Raw Usage',
        'timestamp': '2019-05-06T19:00:00-05:00'
    }
]

result = {i['timestamp']: i['bytesUsed'] for i in arr if start_dt <= parse(i['timestamp']) <= end_dt}
print(result)

output:

{'2019-02-28T19:00:00-05:00': 79095, '2019-04-01T19:00:00-05:00': 310435}

If you don't have dateutil module, can isntall using pip install python-dateutil command. Really didn't get your output, if this is not you expected, please add a comment to this answer.