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rvectortrim

R how to produce a vector trimming another vector by choosing a fixed value of its components

This is an elementary question; I apologize for it. Let x <- c(1,2,3,4,5). I would like to produce a vector z of length 5 s.t. its components are all those x satisfying the condition

if x[i]>2 then write 2.

The result should look like

z <- c(1,2,2,2,2)

I know that 

z <- which(x>2)

gives me

3 4 5

but I cannot find a good way to implement it to arrive at the result. I thank you all for your support.

EDIT. If instead of considering a vector x I have a matrix M with columns x and y and I want to apply the above trimming to the column x leaving y untouched, how should I proceed?

Solution

  • For example:

    y <- x
y[x>2] <- 2
1 2 2 2 2

    If you've a matrix M with two columns, and you want to replace only the first column with values > 2 to 2, then do:

    M[,1][M[,1]>2] <- 2