How to subtract years?

If leap days are to be taken into account then I'd recommend using this lubridate function to subtract months, as other methods will return either March 1st or NA:

> library(lubridate)
> dt %m-% months(12*2)
[1] "2008-03-17"

# Try with leap day
> leapdt <- as.Date('2016/02/29')
> leapdt %m-% months(12*2)
[1] "2014-02-28"

This way seems to do the job as well

dt = as.Date("2010/03/17")
dt-365*2
[1] "2008-03-17"

as.Date("2008/02/29")-365*2
## [1] "2006-03-01"

cur_date <- str_split(as.character(Sys.Date()), pattern = "-")
cur_yr <- cur_date[[1]][1]
cur_month <- cur_date[[1]][2]
cur_day <- cur_date[[1]][3]
new_year <- as.integer(year) - 2
new_date <- paste(new_year, cur_month, cur_day, sep="-")

Using Base R, you can simply use the following without installing any package.

1) Transform your character string to Date format, specifying the input format in the second argument, so R can correctly interpret your date format.

dt = as.Date('2010/03/17',"%Y/%m/%d")

NOTE: If you look now at your enviroment tab you will see dt as variable with the following value "2010-03-17" (Year-month-date separated by "-" not by "/")

2) specify how many years to substract

years_substract=2

3) Use paste() combined with format () to only keep Month and Day and Just substract 2 year from your original date. Format() function will just keep the specific part of your date accordingly with format second argument.

dt_substract_2years<-
as.Date(paste(as.numeric(format(dt,"%Y"))-years_substract,format(dt,"%m"),format(dt,"%d"),sep = "-"))

NOTE1: We used paste() function to concatenate date components and specify separator as "-" (sep = "-")as is the R separator for dates by default.

NOTE2: We also used as.numeric() function to transform year from character to numeric