In R how to create a year vector with a simple rule-CodePudding

I have the first year as 2007. The last year is 2021

I need to create a character vector just like the vector bellow:

c("2007-2008","2007-2010","2007-2012","2007-2014","2007-2016","2007-2018","2007-2021")

The idea is to have: first-year -second year, first-year - first-year 3, first-year - first-year 5, first-year - first-year 7, first-year - first-year 9, first-year - first-year 11, first-year - first-year 13 But when I have first-year - first-year 13 and the next step is bigger than the last year (2021) I consider first-year - lastyear

In other words the difference between the last years should be at least 2 (2008....2010...2012...2014..2016...2018...2020) But once I have 2020 it will lead the next interval 2007-2021 have a difference of 1 year, if this happens I consider 2007-2018and 2007-2021

How can I create something like this in R?

CodePudding user response：

years <- c(2007, 2021)
years <- unique(sort(c(years, seq(1   years[1], years[2], by = 2))))
years
# [1] 2007 2008 2010 2012 2014 2016 2018 2020 2021
years <- years[c(diff(years) >= 2, TRUE)]
years
# [1] 2008 2010 2012 2014 2016 2018 2021
paste(2007, years, sep = "-")
# [1] "2007-2008" "2007-2010" "2007-2012" "2007-2014" "2007-2016" "2007-2018" "2007-2021"

CodePudding user response：

An idea to generate the required sequence directly from seq

st <- 2007
en <- 2021

paste(st, unique(c(seq(st   1, en - 2, 2), en)), sep = "-")
[1] "2007-2008" "2007-2010" "2007-2012" "2007-2014" "2007-2016" "2007-2018"
[7] "2007-2021"