Time - get yesterdays date

datetime, python, time

Solution

To get yesterday's `struct_time`, use any of many existing `datetime` solutions and call `.timetuple()` to get `struct_time` e.g.:

#!/usr/bin/env python
from datetime import date, timedelta

today = date.today()
yesterday = today - timedelta(1)
print(yesterday.timetuple())
# -> time.struct_time(tm_year=2015, tm_mon=4, tm_mday=22, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=2, tm_yday=112, tm_isdst=-1)

It produces the correct day in the local timezone even around DST transitions.

See How can I subtract a day from a python date? if you want to find the corresponding UTC time (get yesterday as an aware `datetime` object).

You could also get yesterday using only `time` module (but less directly):

#!/usr/bin/env python
import time

def posix_time(utc_time_tuple):
    """seconds since Epoch as defined by POSIX."""
    # from https://gist.github.com/zed/ff4e35df3887c1f82002
    tm_year = utc_time_tuple.tm_year - 1900
    tm_yday = utc_time_tuple.tm_yday - 1
    tm_hour = utc_time_tuple.tm_hour
    tm_min = utc_time_tuple.tm_min
    tm_sec = utc_time_tuple.tm_sec
    # http://pubs.opengroup.org/stage7tc1/basedefs/V1_chap04.html#tag_04_15
    return (tm_sec + tm_min*60 + tm_hour*3600 + tm_yday*86400 +
            (tm_year-70)*31536000 + ((tm_year-69)//4)*86400 -
            ((tm_year-1)//100)*86400 + ((tm_year+299)//400)*86400)

now = time.localtime()
yesterday = time.gmtime(posix_time(now) - 86400)
print(yesterday)
# -> time.struct_time(tm_year=2015, tm_mon=4, tm_mday=22, tm_hour=22, tm_min=6, tm_sec=16, tm_wday=2, tm_yday=112, tm_isdst=0)

It assumes that `time.gmtime()` accepts POSIX timestamp on the given platform (Python's stdlib breaks otherwise e.g., if non-POSIX `TZ=right/UTC` is used). `calendar.timegm()` could be used instead of `posix_time()` but the former may use `datetime` internally.

Note: `yesterday` represents local time in both solutions (`gmtime()` is just a simple way to implement subtraction here). Both solutions use naive timezone-unaware time objects and therefore the result may be ambiguous or even non-existent time though unless the local timezone has skipped yesterday (e.g., Russia had skipped several days in February 1918) then the date is correct anyway.

Problem

I'm trying to get todays and yesterdays time using Python's `time` module. This for me works for todays date: ``` dt = time.strptime(time.strftime("%d/%m/%Y"),'%d/%m/%Y') ``` But I don't know how to get yesterdays date. I've found many tutorials where the `datetime` module is used but nothing where `time` module is used. How can I do that? And is there a better way to get todays date (`struct_time`)?

Original source

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