# ErrBars: Add Error Bars to an Existing Plot In DescTools: Tools for Descriptive Statistics

## Description

Add error bars to an existing plot.

## Usage

 ```1 2 3 4``` ```ErrBars(from, to = NULL, pos = NULL, mid = NULL, horiz = FALSE, col = par("fg"), lty = par("lty"), lwd = par("lwd"), code = 3, length = 0.05, pch = NA, cex.pch = par("cex"), col.pch = par("fg"), bg.pch = par("bg"), ...) ```

## Arguments

 `from` coordinates of points from which to draw (the lower end of the error bars). If `to` is left to `NULL` and `from` is a k x 2 dimensional matrix, the first column will be interpreted as `from` and the second as `to`. `to` coordinates of points to which to draw (the upper end of the error bars). `pos` numeric, position of the error bars. This will either be the x-coordinate in case of vertical error bars and the y-coordinate in case of horizontal error bars. `mid` numeric, position of midpoints. Defaults to the mean of `from` and `to`. `horiz` logical, determining whether horizontal error bars are needed (default is FALSE). `col` the line color. `lty` the line type. `lwd` line width. `code` integer code, determining where end lines are to be drawn. `code = 0` will draw no end lines, `code = 1` will draw an end line on the left (lower) side at (`x0[i]`, `y0[i]`), `code = 2` on the right (upper) side (`x1[i]`, `y1[i]`) and `code = 3` (default) will draw end lines at both ends. `length` the length of the end lines. `pch` plotting character for the midpoints. The position of the points is given by `mid`. If `mid` is left to `NULL` the points will be plotted in the middle of `from` and `to`. No points will be plotted if this is set to `NA`, which is the default. `cex.pch` the character extension for the plotting characters. Default is `par("cex")`. `col.pch` the color of the plotting characters. Default is `par("fg")`. `bg.pch` the background color of the plotting characters (if pch is set to 21:25). Default is `par("bg")`. `...` the dots are passed to the `arrows` function.

## Details

A short wrapper for plotting error bars by means of `arrows`.

## Author(s)

Andri Signorell <andri@signorell.net>

`arrows`, `lines.loess`
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14``` ```par(mfrow=c(2,2)) b <- barplot(1:5, ylim=c(0,6)) ErrBars(from=1:5-rep(0.5,5), to=1:5+rep(0.5,5), pos=b, length=0.2) # just on one side b <- barplot(1:5, ylim=c(0,6)) ErrBars(from=1:5, to=1:5+rep(0.5,5), pos=b, length=0.2, col="red", code=2, lwd=2) b <- barplot(1:5, xlim=c(0,6), horiz=TRUE) ErrBars(from=1:5, to=1:5+rep(0.2,5), pos=b, horiz=TRUE, length=0.2, col="red", code=2, lwd=2) par(xpd=FALSE) dotchart(1:5, xlim=c(0,6)) ErrBars(from=1:5-rep(0.2,5), to=1:5+rep(0.2,5), horiz=TRUE, length=0.1) ```