将季度年转换为 R 中季度的最后日期

Question

I have an issue when I use as.Date(as.yearqtr(test[,1],format ="%qQ%Y"),frac =1) , but it returns an error,and quater-year didn't change to date. The error is: error in as.yearqtr(as.numeric(x)) (list) object cannot be coerced to type 'double'

This is my dataframe in R.

 TIME VALUE 1Q2019 1 2Q2019 2 3Q2019 3 4Q2019 4

The ideal output is

 TIME VALUE 2019-03-31 1 2019-06-30 2 2019-09-30 3 2019-12-31 4

Answer 1

We can convert to Date with zoo and get the last date of the quarter with frac . We use some RegEx to rearrange in zoo 's suitable format:

df$TIME=as.Date(as.yearqtr(gsub("(\\d)(Q)(\\d{1,})","\\3 Q\\1",df$TIME)),frac = 1)
 df
        TIME VALUE
1 2019-03-31     1
2 2019-06-30     2
3 2019-09-30     3
4 2019-12-31     4

Data:

df <-structure(list(TIME = structure(1:4, .Label = c("1Q2019", "2Q2019", 
"3Q2019", "4Q2019"), class = "factor"), VALUE = 1:4), class = "data.frame", row.names = c(NA, 
-4L))

Answer 2

Here is a function that will return a vector of dates, given an input vector in the form of 1Q2019...

dateStrings <- c("1Q2019","2Q2019","3Q2019","4Q2019","1Q2020")

lastDayOfQuarter <- function(x){
     require(lubridate)
     result <- NULL
     months <-c(3,6,9,12)
     days <- c(31,30,30,31)

     for(i in 1:length(x)) {
          qtr <- as.numeric(substr(x[i],1,1))
          result[i] <- mdy(paste(months[qtr],days[qtr],(substr(x[i],3,6)),sep="-")) 
     }
     as.Date(result)

}
lastDayOfQuarter(dateStrings)

and the output:

>lastDayOfQuarter(dateStrings)
[1] "2019-03-31" "2019-06-30" "2019-09-30" "2019-12-31" "2020-03-31"
>