# colVars: Column and row-wise variances and standard deviations of a... In Rfast: A Collection of Efficient and Extremely Fast R Functions

 Column and row-wise variances and standard deviations R Documentation

## Column and row-wise variances and standard deviations of a matrix

### Description

Column and row-wise variances and standard deviations of a matrix

### Usage

``````## S3 method for class 'matrix'
colVars(x, std = FALSE, na.rm = FALSE, parallel = FALSE, cores = 0)
## S3 method for class 'data.frame'
colVars(x, std = FALSE, na.rm = FALSE, parallel = FALSE, cores = 0)
colVars(x, std = FALSE, na.rm = FALSE, parallel = FALSE, cores = 0)
rowVars(x, std = FALSE, na.rm = FALSE, parallel = FALSE, cores = 0)
``````

### Arguments

 `x` A matrix with the data. `std` A boolean variable specyfying whether you want the variances (FALSE) or the standard deviations (TRUE) of each column. `na.rm` TRUE or FAlSE for remove NAs if exists. `parallel` Should parallel implentations take place in C++? The default value is FALSE. `cores` Number of cores to use for parallelism. Valid only when argument parallel is set to TRUE. Default value is 0 and it means the maximum supported cores.

### Details

We found this on stackoverflow which was created by David Arenburg. We then modified the function to match the sums type formula of the variance, which is faster.

### Value

A vector with the column variances or standard deviations.

### Author(s)

``` colmeans, colMedians, colrange ```
``````x <- matrix( rnorm(100 * 100), ncol = 100 )