R: How can I convert non-intuitive strings that describe hours, minutes, and seconds to a workable POSIXct format to perform standard arithmatic on?

I have a data set in R that has values in hours, minutes, and seconds format. However, some values only have hours and minutes, some only have minutes and seconds, some only have minutes, and some only have seconds. It’s also not formatted very favorably. Sample data can be found below:

example <- as.data.frame(c("22h28m", "17m7s", "15m", "14s"))

I’d like to convert it to a POSIXct format like the below, with the goal of adding/subtracting time:

I’ve tried as POSIXct() and strptime() formulas, but to no avail. Any help would be greatly appreciated – thanks!

>Solution :

Maybe parse_date_time from lubridate?

library("lubridate")
x <- c("22h28m", "17m7s", "15m", "14s")
y <- parse_date_time(x, orders = c("%Hh%Mm%Ss", "%Hh%Mm", "%Hh%Ss", "%Mm%Ss", "%Hh", "%Mm", "%Ss"), exact = TRUE)
y
## [1] "0000-01-01 22:28:00 UTC"
## [2] "0000-01-01 00:17:07 UTC"
## [3] "0000-01-01 00:15:00 UTC"
## [4] "0000-01-01 00:00:14 UTC"

To get a number of seconds since midnight, you could do:

y0 <- ymd_hms("0000-01-01 00:00:00")
dy <- y - y0
dy
## Time differences in secs
## [1] 80880  1027   900    14

Then you could add dy to any reference time given as a length-1 POSIXct object. For example, the most recent midnight:

y0 <- floor_date(now(), unit = "day")
y0 + dy
## [1] "2022-02-03 22:28:00 EST"
## [2] "2022-02-03 00:17:07 EST"
## [3] "2022-02-03 00:15:00 EST"
## [4] "2022-02-03 00:00:14 EST"