Add text using relative plot region coordinates

Here is a simple but useful function for adding text to a plot device using the relative x, y coordinates (i.e. between 0 and 1). I found myself programming these few lines repeatedly and decided to finally bundle it into a function, called reltext(). The function can be found below, and is also available in the sinkr package (https://github.com/marchtaylor/sinkr).

Rotated axis labels in R plots

It's somehow amazing to me that the option for slanted or rotated axes labels is not an option within the basic plot() or axis() functions in R.  The advantage is mainly in saving plot area space when long labels are needed (rather than as a means of preventing excessive head tilting). The topic is briefly covered in this FAQ, and the solution is a bit tricky, especially for a new R user. Below is an example of this procedure.

To reproduce example:

Data mountains and streams - stacked area plots in R

Below are two functions for producing stacked area plots. The first is the more typical approach where sequential series are stacked on top of another (function: plot.stacked), while the second approach is the more aesthetically-oriented version called a "stream plot" (function: plot.stream), which alternates series on either side of a meandering baseline (see here for the motivation, and here for the inspiration). 

Arguments are similar for both functions regarding the input of x and y series and polygon attributes (fill color, border color, border line width). The stream plot also requires that the degree of meandering for the baseline be defined by the arguments frac.rand and spar; frac.rand, controls the meander amplitude (uniform random numbers added to baseline as a fraction of the total y range) and spar controls the amount of smoothing (as fit by the function smooth.spline).

The plot above colors the series with a color gradient of when the first appear in the series, while the plot below colors series by their maximum value. The order of the plotting of the series can also affect the the emphasis on the plot. By default, plotting order is sequential by column, although two ordering options are built-in to the functions: order by maximum value, and order by first appearance.

The plot.stacked function: