**ggtern: ternary diagrams in R**, and kindly contributed to R-bloggers)

ggtern 1.0.3.1 has introduced a new series of geometries to represent known errors in data, they are relatively easy to use and are along the lines of the `geom_errorbar(...)`

and `geom_errorbarh(...)`

geometries in ggplot2.

Analagous the errorbars in ggplot2, in ggtern, the new geometries **[and additional required mappings]** are thus listed as follows:

- geom_errorbarT(…)
**[Tmin, Tmax]** - geom_errorbarL(…)
**[Lmin, Lmax]** - geom_errorbarR(…)
**[Rmin, Rmax]**

These three geometries represent errors relative to the Top, Left and Right apex species, respectively.

## Example of Ternary Errorbar Usage

To start with, let us prepare some data:

# Load the data data(Feldspar) IX = c('Ab', 'An', 'Or') #Error bar width width <- 0.01 #Create error data +- 5% for (ix in IX) { Feldspar[, paste0(ix, '_min')] = pmax(Feldspar[, ix] - 5, 0) Feldspar[, paste0(ix, '_max')] = pmin(Feldspar[, ix] + 5, 100) } #Helper mytitle <- function(x){ ggtitle(paste('Demonstration of: geom_errorbar',x,'(...)',sep="")) } # Set the theme for subsequent plots theme_set(theme_bw())

Top species error bars can be produced with the following:

ggtern(data = Feldspar, aes(x = Ab, y = An, z = Or)) + geom_errorbarT(aes(Tmin = An_min, Tmax = An_max, width = width), color = 'darkred') + geom_point() + mytitle("T")

Left species error bars can be produced in exactly the same manner:

ggtern(data = Feldspar, aes(x = Ab, y = An, z = Or)) + geom_errorbarL(aes(Lmin = Ab_min, Lmax = Ab_max, width = width), color = 'darkblue') + geom_point() + mytitle("L")

Right species error bars, you guessed it, same again:

ggtern(data = Feldspar, aes(x = Ab, y = An, z = Or)) + geom_errorbarR(aes(Rmin = Or_min, Rmax = Or_max, width = width), color = 'darkgreen') + geom_point() + mytitle("R")

Voila!

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