Converting data from yyyyMM to yyyyQQ

Question

My date data is in the format "yyyymm", specifically 20071 / 20074 / 20077 / 200710.

I want to convert this to quarters.

Also, in another dataset I have monthly data that I want to aggregate to quarters. Is there a function?

Answer 1

In base R, you could append a temporary date and extract year and quarter from it.

x <- as.character(c(20071, 20074, 20077, 200710))
temp <- as.Date(paste(x, "01"), "%Y%m %d")
paste(format(temp, "%Y"), quarters(temp))
#[1] "2007 Q1" "2007 Q2" "2007 Q3" "2007 Q4"

If you want quarter as numbers, we can use lubridate::quarter

paste(format(temp, "%Y"), lubridate::quarter(temp))
#[1] "2007 1" "2007 2" "2007 3" "2007 4"

Answer 2

The yearqtr class repesents a year and quarter internally as a year plus a fraction (0 for Q1, 1/4 for Q2, 2/4 for Q3 and 3/4 for Q4) and displays as shown:

library(zoo)
ym <- c(20071, 20074, 20077, 200710) # test data

yq <- as.yearqtr(as.character(ym), "%Y%m")
yq
## [1] "2007 Q1" "2007 Q2" "2007 Q3" "2007 Q4"

It is probably preferable to leave it as yearqtr since you can perform many operations on it (eg yq + 1/4 is the next quarter) but if you want it as pure character strings use format(yq) or as.character(yq) .