CODEWITHSUNDEEP
rdata.table
rosscova
rosscova

Reputation: 5600

Convert integer to ITime?

I'm looking into using the new data.table date and time formats. Since ITime is stored as an integer under the hood (number of seconds since midnight):

x <- as.ITime( "10:25:00" )
i <- as.integer( x )
i
[1] 37500

It seems like it should be easy enough to convert an integer (assuming it's less than 24*60*60) to ITime, but I'm not finding how:

as.ITime( i )
Error in as.POSIXlt.numeric(x, ...) : 'origin' must be supplied

as( i, "ITime" )
Error in as(i, "ITime") : 
  no method or default for coercing “integer” to “ITime”

Providing an origin (which I gather gets passed to as.POSIX...) does help, but even then it only gives the right value (for my locale anyway) if you also specify tz as "UTC":

as.ITime( i, origin = "1970-01-01 00:00:00" )
[1] "20:25:00"

as.ITime( i, origin = "1970-01-01 00:00:00", tz = "UTC" )
[1] "10:25:00"

# note that the date seems necessary but irrelevant here
as.ITime( i, origin = "2000-01-01 00:00:00", tz = "UTC" )
[1] "10:25:00"

What I'm talking about is something similar to what I sometimes use with chron::times:

x <- chron::times( "10:25:00" )

n <- as.numeric( x )
n
[1] 0.4340278

chron::times( n )
[1] 10:25:00

Is a similar (except using integers instead of numbers/doubles/floats) method available with the ITime class?

Note I'm aware of the same "origin required" issue with IDate, Date, etc., but that makes more sense to me since origin="1970-01-01" is a lot less of a robust standard compared with using "midnight" as an origin for time (I use some data sources with different ideas on which date should be called the "origin").

Upvotes: 5

Views: 1549

Answers (1)

Frank
Frank

Reputation: 66819

This works:

library(data.table)
DT = data.table(int = 37500L)
DT[, setattr(int, "class", "ITime")]

#         int
# 1: 10:25:00

or 

int = 37500L
setattr(int, "class", "ITime")

# "10:25:00"

Upvotes: 5

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