Modifies a value

This function does the same as x <- x + sign*value, but without repeating x. The expression modify(x) <- rnorm(length(x),0,1) will add Gaussian noise to it. This is meant as a replacement for the x += 1 syntax of C, it exists only for aesthetic reasons.

Usage

modify(x, i = seq(NROW(x)), j = seq(NCOL(x)), sgn = +1) <- value

Arguments

x

a numeric value to be modified

i

row-indices of x to be modified

j

column-indices of x to be modified

sgn

modification

value

a numeric value of appropriate size, depending on i and j

Value

The value of x is modified additively ihn place: x <- x + sgn*value

Details

Specifically, this function should work for matrices, and it is possible to supply row and column index vectors: x[i,j] will be modified.

This function is quite useful if x has a very long name, e.g. experiments[[1]]$func.

Examples

 x <- matrix(seq(12),3,4)
 modify(x,seq(2),seq(2)) <- 10
 print(x)
#>      [,1] [,2] [,3] [,4]
#> [1,]   11   14    7   10
#> [2,]   12   15    8   11
#> [3,]    3    6    9   12