Rose diagram in R

Question

I want to draw a rose diagram of some circular data. I have been using the circular package and within this package it allows you to draw a simple rose diagram using the function: rose.diag. While this draws the diagram I want to be able to improve the plots but I can't find away to add to the plot or adjust it slightly. I have looked at drawing it in ggplot2 but this doesn't seem clear to me and I am struggling to find another package in R which draws rose diagrams like this.

I post a sample of data and my current code below along with my queries:

Angle
0.65454759
0.01355458
0.5052027
0.2264302
-0.350552
-0.428481
0.1231778
0.258787
0.06723504
0.06906181
2.54608572
-1.6591672
3.00437314
-0.0503291
-0.828578
-1.9616418
-0.6468774
0.01438686
0.1162713
0.9938797
0.1861583
0.1547071
0.2577813
0.5110576
0.08714113

These data are radian turning angles. Using the circular package I make this data a vector of class circular:

x <- circular(Angle)

Then draw a rose diagram using the following code where it plots the diagram in degrees and not radians:

rose.diag(x, pch = 16, cex = 1, axes = TRUE, shrink = 1, col=3, prop = 2, 
    bins=36, upper=TRUE, ticks=TRUE, units="degrees")

There are 3 things I would like to add to this plot:

1. Change the plot orientation so that 0 is at the top and not on the right.
2. Add concentric circles to the plot to help with visual interpretation of the size and weight of each of the "bins".
3. Add a line to identify the mean angle (with sd error bars if possible)

Answer 1

There are a few ways to do this. There is a "zero" argument for rose.diag in this package.

y <- scan() # paste in the values from the question and hit return twice
y <- circlar(y) # not necessary but prevents a warning
rose.diag(y, units = 'degrees', zero = pi/2) # units doesn't change the underlying units

Alternatively you could have set properties of the circular object that you created.

y <- circlar(y, zero = pi/2)
rose.diag(y, units = 'degrees') # note, no 0 call here

So, now the plot is rotated... how to add stuff...

> par('usr')
[1] -1.376553  1.376553 -1.123200  1.123200

That gives me user coordinates and tells me the plot dimensions in user space. Now I can do things like add a circle.

symbols(0, 0, circle = 0.2, inches = FALSE, add = TRUE, fg = 'red')

There is a lines.circular function but it wasn't obvious to me how to use it. I could also plot a line using segments or arrows commands and draw right on the plot with them. It requires a bit of euclidean geometry to convert an angle and length of the line to points. This should all get you started.

m <- mean.circle(y)
segments(0, 0, cos(m+pi/2), sin(m+pi/2), col = 'red') # note I need to add the new 0 position... there is a lines.circular function but it wasn't obvious to me how to use it.

(tip... the framing circle in rose.diag is at a radius of 1 so giving that to the circle argument in symbols will draw exactly at that point)