# Skewness coefficients of a folder of data sets

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### Description

Computes the skewness coefficient by column of the elements of an object of class `folder`.

### Usage

 `1` ```skewnessf(fold, na.rm = FALSE) ```

### Arguments

 `fold` an object of class `folder`. The attribute `attr(,"same.cols")` must be `TRUE` (otherwise, there is an error). `na.rm` logical. Should missing values be omitted from the calculations? (see `skewness`)

### Details

This function can only be applied to a folder of data frames with the same column names. If `attr(fold,"same.cols") = FALSE`, there is an error.

It uses `skewness` to compute the mean by numeric column of each element of the folder. If some columns of the data frames are not numeric, there is a warning, and the means are computed on the numeric columns only.

### Value

A list whose elements are the skewness coefficients by column of the elements of the folder.

### Author(s)

Rachid Boumaza, Pierre Santagostini, Smail Yousfi, Sabine Demotes-Mainard

Maintainer: Rachid Boumaza <rachid.boumaza@agrocampus-ouest.fr>

`folder` to create an object is of class `folder`. `meanf`, `varf`, `corf`, `kurtosisf` for other statistics for `folder` objects.
 ``` 1 2 3 4 5 6 7 8 9 10 11``` ```# First example: iris (Fisher) data(iris) iris.fold <- df2folder(iris, "Species") iris.skewness <- skewnessf(iris.fold) print(iris.skewness) # Second example: roses data(roses) roses.fold <- df2folder(roses, "Lot") roses.skewness <- skewnessf(roses.fold) print(roses.skewness) ```