How to find Previous Sunday in R

Question

It seems the Internet has not answered this question for R yet:

If I have a date. Say the 20th of march: as.Date(\"2015-03-20\") how do I get, in R, the previous Sun

Answer 1

One way:

d<-as.Date("2015-03-20")
d-as.POSIXlt(d)$wday
## [1] "2015-03-15"

There;s also the more hackish way, using the fact that dates are represented as integers with day zero being a Thursday (Jan 1 1970):

d-((as.numeric(d)+4)%% 7)
## [1] "2015-03-15"