calculate difference between two times

how to calculate the difference in minutes between 2 times
Start_time end_time
17:15:49 17:22:44

additionally the type of these variable is (unknown) how to convert it to time?

Hello @Marwa_Abd_Elfattah ,

dates and times I allways find a bit tricky and therefore I like to use the R package lubridate.
If you don't know the type it is probably character but if the dates comes from a spreadsheet they could be numeric. For now assuming they are character and already given in a data.frame you could do this.

#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#>     filter, lag
#> The following objects are masked from 'package:base':
#>     intersect, setdiff, setequal, union
#> Attaching package: 'lubridate'
#> The following objects are masked from 'package:base':
#>     date, intersect, setdiff, union

df <- data.frame( 
     stringsAsFactors = F,
     start = c("17:15:49","17:22:44"),
     end   = c("17:22:44","18:00:00")

#>      start      end
#> 1 17:15:49 17:22:44
#> 2 17:22:44 18:00:00

df %>% 
  mutate(start = lubridate::parse_date_time(start,"%H:%M:%S"),
         end = lubridate::parse_date_time(end,"%H:%M:%S"),
         dif = end - start)  
#>                 start                 end            dif
#> 1 0000-01-01 17:15:49 0000-01-01 17:22:44  6.916667 mins
#> 2 0000-01-01 17:22:44 0000-01-01 18:00:00 37.266667 mins
Created on 2021-09-16 by the reprex package (v2.0.0)

You see that the characters are converted to date-time type (with the same date !!) and then the difference is taken. I hope this matches your problem and otherwise just ask here.

first thanks for the reply. But it didn't work and converted all the started_ and ended _at values to NA. and the following error is appeared.

Warning messages:
1: Problem with mutate() column started_at.
i started_at = parse_date_time(started_at, "%H:%M:%S").
i All formats failed to parse. No formats found.
2: Problem with mutate() column ended_at.
i ended_at = parse_date_time(ended_at, "%H:%M:%S").
i All formats failed to parse. No formats found.

If you need more specific help, please provide a proper REPRoducible EXample (reprex) illustrating your issue.

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