# isoportion: Isoportion- and Isoproportion-lines In compositions: Compositional Data Analysis

## Description

Add lines of equal portion and proportion to ternary diagrams, to serve as reference axis.

## Usage

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15``` ```isoPortionLines(...) ## S3 method for class 'acomp' isoPortionLines(by=0.2,at=seq(0,1,by=by),..., parts=1:3,total=1,labs=TRUE,lines=TRUE,unit="") ## S3 method for class 'rcomp' isoPortionLines(by=0.2,at=seq(0,1,by=by),..., parts=1:3,total=1,labs=TRUE,lines=TRUE,unit="") isoProportionLines(...) ## S3 method for class 'acomp' isoProportionLines(by=0.2,at=seq(0,1,by=by),..., parts=1:3,labs=TRUE,lines=TRUE) ## S3 method for class 'rcomp' isoProportionLines(by=0.2,at=seq(0,1,by=by),..., parts=1:3,labs=TRUE,lines=TRUE) ```

## Arguments

 `...` graphical arguments `at` numeric in [0,1]: which portions/proportions should be marked? `by` numeric in (0,1]: steps between protions/proportions `parts` numeric vector subset of {1,2,3}: the variables to be marked `total` the total amount to be used in labeling `labs` logical: plot the labels? `lines` logical: plot the lines? `unit` mark of the units e.g. "%"

## Details

Isoportion lines give lines of the same portion of one of the parts, while isoproportion line gives lines of the same ratio between two parts. The isoproportion lines are straight lines in both the Aitchison and the real geometries of the simplex, while the isoportion lines are not straight in an Aitchison sense (only in the real one). However, note that both types of lines remain straight in the real sense when perturbed (von Eynatten et al., 2002).

## Note

Currently IsoLines only works with individual plots. This is mainly due to the fact that I have no idea, what the user interface of this function should look like for multipanel plots. This includes philosophical problems with the meaning of isoportions in case of marginal plots.

## Author(s)

K.Gerald v.d. Boogaart http://www.stat.boogaart.de

## References

von Eynatten, H., V. Pawlowsky-Glahn, and J.J. Egozcue (2002) Understanding perturbation on the simplex: a simple method to better visualize and interpret compositional data in ternary diagrams. Mathematical Geology 34, 249-257

`plot.acomp`
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13``` ```data(SimulatedAmounts) plot(acomp(sa.lognormals)) isoPortionLines() plot(acomp(sa.lognormals),center=TRUE) isoPortionLines() plot(rcomp(sa.lognormals)) isoPortionLines() plot(acomp(sa.lognormals)) isoProportionLines() plot(acomp(sa.lognormals),center=TRUE) isoProportionLines() plot(rcomp(sa.lognormals)) isoProportionLines() ```