CODEWITHSUNDEEP
rdatetimesubsetzoo
bumblebee
bumblebee

Reputation: 1116

subsetting yearmon objects

I have monthly data 

library(zoo); library(data.table)
dat <- data.table(month=as.yearmon(paste0("2019-0",1:9)))
> dat
      month
1: Jan 2019
2: Feb 2019
3: Mrz 2019
4: Apr 2019
5: Mai 2019
6: Jun 2019
7: Jul 2019
8: Aug 2019
9: Sep 2019

and I would like to subset it to months after, say, May 2019. Whereas

dat[month=="Jun 2019"]

works,

> dat[month > "May 2019"]
Empty data.table (0 rows and 1 cols): month
> dat[month%in%c("Jun 2019","Jul 2019")]
Empty data.table (0 rows and 1 cols): month

do not. Is there a trick?

Upvotes: 0

Views: 359

Answers (1)

G. Grothendieck
G. Grothendieck

Reputation: 269461

Actually it does work. Fixing the double quotes we have:

library(data.table)
library(zoo)

dat <- data.table(month=as.yearmon(paste0("2019-0",1:9), "%Y-%m"))

dat[month > "May 2019"]
##       month
## 1: Jun 2019
## 2: Jul 2019
## 3: Aug 2019
## 4: Sep 2019

Language

The comparison will use the language currently in effect. For example, if we set the current session to French:

Sys.setlocale(locale = "French")
dat[ month > "mai 2019" ]
##         month
## 1:  juin 2019
## 2: juil. 2019
## 3:  août 2019
## 4: sept. 2019

We can also do it in a language independent way by using month numbers rather than names:

dat[ month > "2019-05" ]
##       month
## 1: Jun 2019
## 2: Jul 2019
## 3: Aug 2019
## 4: Sep 2019

Note

It would be good enough to do this to create the example:

dat <- data.table(month = as.yearmon(paste0("2019-", 1:9)))

Upvotes: 1

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