makemissing: Create random missing data

Description

Generates missing entries in data.frame/matrix

makemissing(data, p = 0.2, cols = seq_len(ncol(data)), rowwise = FALSE,
  nafun = function(x) x)

data

data.frame

Fraction of missing data in each column

cols

Which columns (name or index) to alter

rowwise

Should missing occur row-wise (either none or all selected columns are missing)

nafun

(Optional) function to be applied on data.frame before return (e.g. na.omit to return complete-cases only)