wkeep function

Keep part of vector or matrix

Extract elements from a vector or matrix.

wkeep(x, l, opt = "centered")

Arguments

• x: input data, specified as a numeric vector or matrix.

• l: either a positive integer value, specifying the length to extract from the input vector x, or a vector of length 2, indicating the submatrix to extract from the matrix x. See the examples.

• opt: One of:

  • character string: matched against c("centered", "left", "right"), indicating the location of the vector x to extract
  • positive integer: starting index of the input vector x
  • two-element vector: starting row and columns from the matrix x

  See the examples. Default: "centered".

Returns

extracted vector or matrix

Examples

## create a vector
x <- 1:10
## Extract a vector of length 6 from the central part of x.
y <- wkeep(x, 6, 'c')

## Extract two vectors of length 6, one from the left part of x, and the
## other from the right part of x.
y <- wkeep(x, 6, 'l')
y <- wkeep(x, 6, 'r')

## Create a 5-by-5 matrix.
x <- matrix(round(runif(25, 0, 25)), 5, 5)

## Extract a 3-by-2 matrix from the center of x
y <- wkeep(x, c(3, 2))

## Extract from x the 2-by-4 submatrix starting at x[3, 1].
y <- wkeep(x, c(2, 4), c(3, 1))

Author(s)

Sylvain Pelissier, sylvain.pelissier@gmail.com .

Conversion to R by Geert van Boxtel, G.J.M.vanBoxtel@gmail.com .