[R] polar.plot text labels for data points

[Jim Lemon]

On 05/06/2010 03:24 AM, Tali wrote:
>
> Hello All.
>
> I am using polar.plot from the {plotrix} library to visualize individual
> coral colonies, dying, growing, etc through time. These coral colonies, that
> I visit annually happen to be delineated by a circular plot underwater;
> hence polar.plot is the best way to visualize my data. (I.e. This is not
> cyclical data that I am plotting.) I am trying to label individual data
> points (which correspond to actual coral colonies) with their identifying
> tag numbers. I have searched and searched and found no polar.plot with text
> labels on data points.
>
> I tried to coerce the "text" function (code below). But no dice.
>
>     D = runif(29,0,7)         #Distance from center of circular plot (in
> meters)
>     H = runif(29,0,360)      #Compass heading to center of circular plot (in
> degrees)
>
>     polar.plot(D, H,rp.type = "dots", start = 90, point.col = "red")
>
>     TagID = 200:228          #Labels of individual coral colonies
>     text(D,H,TagID)            #lame attempt at coercing the text function
>
>
> Is it possible to add text labels to data points in polar.plot?
>
Hi Tali,
What a great idea!

radial.labels<-function(lengths,radial.pos,units="radians",start=0,clockwise=FALSE,
  labels,adj=NULL,pos=NULL,...) {

  if(units == "clock24") radial.pos<-pi*(450-radial.pos*15)/180
  if(units == "polar") radial.pos<-pi*radial.pos/180
  if(clockwise) radial.pos<--radial.pos
  if(start) radial.pos<-radial.pos+start
  # get the vector of x positions
  xpos<-cos(radial.pos)*lengths
  # get the vector of y positions
  ypos<-sin(radial.pos)*lengths
  text(xpos,ypos,labels,adj=adj,pos=pos,...)
}

You have now immortalized yourself in the plotrix NEWS file. The next 
version will include this function. Briefly, pass the same "lengths", 
pass your "polar.pos" as "radial.pos" and set units to "polar". The 
other arguments are the same as in radial.plot and text.

> Any assistance will help save an endangered species. (Really!)

I hope that the endangered species to be saved is humanity.

Jim