Error creating R data.table with date-time POSIXlt
data.table, r
Solution
Formatting response from Blue Magister's comment (thanks so much), data.table does not support POSIXlt data types for performance reason -- see cast string to IDateTime as suggested as possible duplicate.
So the way to go is to cast time as ITime (type provided by data.table) or date-time (or date only) as POSIXct, depending upon whether date info is important or not:
> mdt <- data.table(id=1:3, d=as.ITime(strptime(c("06:02:36", "06:02:48", "07:03:12"), "%H:%M:%S")))
> print(mdt)
id d
1: 1 06:02:36
2: 2 06:02:48
3: 3 07:03:12
> mdt <- data.table(id=1:3, d=as.POSIXct(strptime(c("06:02:36", "06:02:48", "07:03:12"), "%H:%M:%S")))
> print(mdt)
id d
1: 1 2014-01-31 06:02:36
2: 2 2014-01-31 06:02:48
3: 3 2014-01-31 07:03:12
As an extra note in case someone can benefit from it, I wanted to create date & time from my input data with date & time in separate fields. I found it useful to learn (see ?ITime) that one can add time ITime to date-time POSIXct and get a date-time POSIXct as follows:
> mdt <- as.POSIXct("2014-01-31") + as.ITime("06:02:36")
> print(mdt)
[1] "2014-01-31 06:02:36 EST"
> class(mdt)
[1] "POSIXct" "POSIXt"
Problem
Problem creating data.table with date-time column: ``` > mdt <- data.table(id=1:3, d=strptime(c("06:02:36", "06:02:48", "07:03:12"), "%H:%M:%S")) > class(mdt) [1] "data.table" "data.frame" > print(mdt) Error in `rownames<-`(`*tmp*`, value = paste(format(rn, right = TRUE), : length of 'dimnames' [1] not equal to array extent Enter a frame number, or 0 to exit 1: print(list(id = 1:3, d = list(sec = c(36, 48, 12), min = c(2, 2, 3), hour = c(6, 6, 7), mday = c(31, 2: print.data.table(list(id = 1:3, d = list(sec = c(36, 48, 12), min = c(2, 2, 3), hour = c(6, 6, 7), m 3: `rownames<-`(`*tmp*`, value = paste(format(rn, right = TRUE), ":", sep = "")) ``` Create as data.frame and convert to data.table works! ``` > mdf <- data.frame(id=1:3, d=strptime(c("06:02:36", "06:02:48", "07:03:12"), "%H:%M:%S")) > print(mdf) id d 1 1 2014-01-31 06:02:36 2 2 2014-01-31 06:02:48 3 3 2014-01-31 07:03:12 > mdt <- as.data.table(mdf) > print(mdt) id d 1: 1 2014-01-31 06:02:36 2: 2 2014-01-31 06:02:48 3: 3 2014-01-31 07:03:12 > class(mdt) [1] "data.table" "data.frame" ``` Am I missing anything or is it bug? If a bug, where do I report it? Note I use R version 3.0.0 and I see some warnings re. packages built with version 3.0.2. Can it be the problem? Should I upgrade R itself? Everything else I do seems to be working though.