CODEWITHSUNDEEP
r
M Terry
M Terry

Reputation: 183

How can I replace vector values in a sequence at regular intervals in R?

I am trying to replace values of a vector of sequence 1 to 100, such that after every 3 elements, the next 2 are replaced by 0s. for example: 

a<-1:20

I want it to be like this: 

a <- c(1, 2, 3, 0, 0, 6, 7, 8, 0, 0, 11, 12, 13, 0, 0, 16, 17, 18, 0, 0)

is there a way to do this automatically?

thanks for any help

Upvotes: 6

Views: 600

Answers (2)

enroute
enroute

Reputation: 183

here's another way, using seq()

x<-1:20
start_<-4
step_<-5

myseq<-seq(start_,20,by=step_)
x[c(myseq,myseq+1)]<-0
x
# [1]  1  2  3  0  0  6  7  8  0  0 11 12 13  0  0 16 17 18  0  0

Upvotes: 1

akrun
akrun

Reputation: 887691

We can use rep with a recycling logical vector to assign values in certain positions to 0

a[rep(c(FALSE, TRUE), c(3,2))]  <- 0
a
#[1]  1  2  3  0  0  6  7  8  0  0 11 12 13  0  0 16 17 18  0  0

Upvotes: 4

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