CODEWITHSUNDEEP
r
scopa
scopa

Reputation: 523

change column strptime() n data frame r

I have a column that I have already changed to DATE using as.date

> test_subset$Date <- as.Date(test_subset$Date, "%d/%m/%Y")

The next column holds numeric data as the times corresponding to adjacent column of dates. The problem I have is it keeps inserting the current date into this time only column - I specify column "TIME" 

> test_subset[[2]] <- strptime(test_subset[[2]], "%H:%M:%S")

but the result appends the current date to the time.

  1. How do I adjust the "TIME" column to NOT include the current date.
  2. How can I strip out the current date from the "TIME" Column

Upvotes: 0

Views: 1940

Answers (1)

Rich Scriven
Rich Scriven

Reputation: 99331

The date is being inserted because you're using strptime(). You can use format(), since you don't necessarily need a special class for the times. If we have an example vector x,

x <- Sys.time() + 0:5
#[1] "2015-03-05 07:08:27 PST" "2015-03-05 07:08:28 PST"
#[3] "2015-03-05 07:08:29 PST" "2015-03-05 07:08:30 PST"
#[5] "2015-03-05 07:08:31 PST" "2015-03-05 07:08:32 PST"

To get the date only, you can use 

as.Date(format(x, "%F"))
# [1] "2015-03-05" "2015-03-05" "2015-03-05" "2015-03-05"
# [5] "2015-03-05" "2015-03-05"

And to get the time only, use format() again, but with %T.

format(x, "%T")
# [1] "07:08:27" "07:08:28" "07:08:29" "07:08:30" "07:08:31"
# [6] "07:08:32"

If it turns out you do need a time class on the second column, you can use chron::times() which gives a "times" class.

(time <- chron::times(format(x, "%T")))
# [1] 07:08:27 07:08:28 07:08:29 07:08:30 07:08:31 07:08:32
class(time)
# [1] "times"

Upvotes: 1

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