Recommended Date R-Table

Question

I have a csv file with one timestamp column "2000-01-01 12: 00: 00.123456". What is the recommended way to handle this in a data table? I need to deal with grouping, matching / sliding with an IDate column from another table, building time series, etc.

IDateTime("2000-01-01 12:00:00.123456") Error in if (any(neg)) res[neg] = paste("-", res[neg], sep = "") : missing value where TRUE/FALSE needed 

I see this answer in a possible duplicate question in which Matthew suggested manually pour dates into integers. But that is 3 years old, and I wonder if there is now a better way?

Answer 1

IDateTime requires an object of the POSIXct class to work correctly (it looks like it works correctly with the factor transform, and is not sure why). I agree that it is not documented very well and it might be worth opening FR / PR on GH regarding documentation - there is an open queue regarding IDateTime vignette though. And FR already exists, which allows you to work with the character class.

 IDateTime(as.POSIXct("2000-01-01 12:00:00.123456")) # idate itime # 1: 2000-01-01 12:00:00 ## IDateTime(factor("2000-01-01 12:00:00.123456")) ## will also work 

Pay attention to the tz parameter in as.POSIXct if you want to avoid unexpected behavior

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Regardless of the fact that the error is actually caused by the ITime print ITime , which calls format.ITime , see here and here for example, if you run res <- IDateTime("2015-09-29 08:22:00") , this will not result in an error, although res will be NA due to incorrect conversion (I believe) to here (format is only "%H:%M:%OS" ). It seems like a mistake to me, and I still don't know why the factor class works correctly if there is no factor method in methods(as.ITime) . Perhaps due to its integer storage mode, which calls another related method.

Answer 2

Depending on the accuracy required for your time fields, you may need a POSIXct instead of an IDateTime .
The timestamp format stored in the source file can be played back in R to format(Sys.time(), "%Y-%m-%d %H:%M:%OS6") .
When using IDateTime you will lose subseconds, you can play with ITime and see if it is suitable for your needs.
If you stick with POSIXct , then you should be aware of the ?setNumericRounding function, which can be important sometimes, since it affects the ordering and joining of the POSIXct base numeric data type.