r - Divide two difftime objects

Question

I have three time (POSIXct) objects t1, t2, t3 which specify the time duration to complete a task.

I found t1, t2, t3 by doing the following:

t1 <- as.POSIXct("2016-10-30 13:53:34") - as.POSIXct("2016-10-30 13:35:34")
t2 <- as.POSIXct("2016-10-30 14:53:34") - as.POSIXct("2016-10-30 14:35:34")
t3 <- as.POSIXct("2016-10-30 15:50:34") - as.POSIXct("2016-10-30 15:40:34")

I want to find the ratios t1/t3 and t2/t3. However, I get the following error:

t1/t3
# Error in `/.difftime`(t1, t3) : 
#   second argument of / cannot be a "difftime" object

I understood that two difftime objects cannot be divided. Is there any way that I could find the result of dividing two difftime objects?

Answer 1

To divide by a difftime you must convert it to numeric. If, as you stated in a comment, you would like the answer to be expressed in seconds, you can specify the 'secs' units. For example:

t1/as.double(t3, units='secs')

As @JonathanLisic notes, as.double does not generally take a units parameter, and this won't work for generic time classes. It is the S3 method for difftime which takes the parameter.