R: Calculate column deviations from central values
colDevs
R Documentation
Calculate column deviations from central values
Description
colDevs calculates the column deviations of data values from
a central value (mean, median, etc.), possibly stratified by a grouping variable.
Conceptually, the function is similar to a column-wise sweep,
by group, allowing an arbitrary center function.
Usage
colDevs(x, group, center = mean, ...)
Arguments
x
A numeric data frame or matrix.
group
A factor (or variable that can be coerced to a factor) indicating
the membership of each observation in x in one or more groups.
If missing, all the data is treated as a single group.
center
A function used to center the values (for each group if group is specified.
The function must take a vector argument and return a scalar result.
...
Arguments passed down
Details
Non-numeric columns of x are removed, with a warning.
Value
A numeric matrix containing the deviations from the centering function.
Author(s)
Michael Friendly
See Also
colMeans for column means,
sweep
Examples
data(iris)
Species <- iris$Species
irisdev <- colDevs(iris[,1:4], Species, mean)
irisdev <- colDevs(iris[,1:4], Species, median)
# trimmed mean, using an anonymous function
irisdev <- colDevs(iris[,1:4], Species, function(x) mean(x, trim=0.25))
# no grouping variable: deviations from column grand means
# include all variables (but suppress warning for this doc)
irisdev <- suppressWarnings( colDevs(iris) )