scalewt {ade4} R Documentation

## Compute or scale data using (weighted) means, variances and covariances (possibly for the levels of a factor)

### Description

These utility functions compute (weighted) means, variances and covariances for dataframe partitioned by a factor. The scale transforms a numeric matrix in a centred and scaled matrix for any weighting.

### Usage

covwt(x, wt, na.rm = FALSE)
varwt(x, wt, na.rm = FALSE)
scalewt(df, wt = rep(1/nrow(df), nrow(df)), center = TRUE, scale = TRUE)
meanfacwt(df, fac = NULL, wt = rep(1/nrow(df), nrow(df)), drop = FALSE)
varfacwt(df, fac = NULL, wt = rep(1/nrow(df), nrow(df)), drop = FALSE)
covfacwt(df, fac = NULL, wt = rep(1/nrow(df), nrow(df)), drop = FALSE)
scalefacwt(df, fac = NULL, wt = rep(1/nrow(df), nrow(df)), scale = TRUE, drop = FALSE)

### Arguments

 x a numeric vector (varwt) or a matrix (covwt) containg the data. na.rm a logical value indicating whether NA values should be stripped before the computation proceeds. df a matrix or a dataframe containing the data. fac a factor partitioning the data. wt a numeric vector of weights. drop a logical value indicating whether unused levels should be kept. scale a logical value indicating whether data should be scaled or not. center a logical value indicating whether data should be centered or not.

### Details

Functions returns biased estimates of variances and covariances (i.e. divided by n and not n-1)

### Value

For varwt, the weighted variance. For covwt, the matrix of weighted co-variances. For scalewt, the scaled dataframe. For other function a list (if fac is not null) of dataframes with approriate values

### Author(s)

Stephane Dray stephane.dray@univ-lyon1.fr

### Examples

data(meau)
w <- rowSums(meau\$spe)
varwt(meau\$env, w)
varfacwt(meau\$env, wt = w)
varfacwt(meau\$env, wt = w, fac = meau\$design\$season)
covfacwt(meau\$env, wt = w, fac = meau\$design\$season)
scalewt(meau\$env, wt = w)

[Package ade4 version 1.7-4 Index]