Calculating difference between time variables

[Michael Duarte Goncalves]

Hi everyone,

I need to calculate a time difference, between two variables: start_time and end_time[_n-1].

But with a special condition:

• If end_time[_n-1] for individual i begins before 9 p.m. and start_time continues after 9p.m. up to 9a.m, I should create a new variable that takes into account the total amount of time elapsed since -end_time[_n-1] (trip 1) and start_time (trip 2), and then substract from this amount the time in which parking spots are free (to give a little context, parking is free from 9 p.m. until 9 a.m.). I have already a variable (interlude) that is the time elapsed since end_time[_n-1] and start_time. But I need to create a new variable that substracts the time between the free scheme range (the fraction of time between 9 p.m. and 9 a.m.,) from the -interlude- variable. Could you give me some insights, please?

I mention before that I need a creation of a new variable, but it could perfectly just to replace the interlude variable by what I mentioned above


dataex:

* Example generated by -dataex-. For more info, type help dataex
clear
input str9 individ_ID double(start_time end_time) float interlude
"1000154_1" 59400000 60300000   .
"1000154_1" 79200000 81000000 315
"1000154_2" 64800000 66600000   .
"1000154_2" 79200000 81000000 210
"1000289_1" 28800000 30600000   .
"1000289_1" 36000000 37800000  90
"1000289_3" 35400000 36000000   .
"1000289_3" 52200000 54000000 270
"1000289_3" 61200000 62400000 120
"1000289_3" 75600000 76800000 220
end
format %tC start_time
format %tC end_time

-interlude-'s creation

by individ_ID (start_time), sort: gen interlude = ///
    clockdiff(end_time[_n-1], start_time, "m") if _n > 1 & (end_time[_n-1] < start_time | date[_n-1] < date)

Thank you in advance.
Best,
--
Michael

[Michael Duarte Goncalves]

Hi everyone,

Could anyone give me some insights please?
Thank you in advance.

Best regards,
Michael

[Michael Duarte Goncalves]

I have tried this code, but not sure it is optimal...

gen interlude_time_diff = .
gen nine_pm = clock("21:00:00", "hms")
format %tC nine_pm

sort individ_ID start_time
quietly by individ_ID: gen actual_start_time = start_time if _n > 1
format %tC actual_start_time

forval i = 2/`=_N' {
    if actual_start_time[`i'] > nine_pm & end_time[`i'-1] < nine_pm {
        replace interlude_time_diff = clockdiff(nine_pm, actual_start_time [`i'], "m") in `i'
    }
}

don't hesitate to give me your feedback or suggestions for improvement, please.

Thank you a lot in advance.

Michael