How to draw an arc from one point to another using ggplot

[gireesh bogu]

Is it possible to draw something like this using ggplot ?

www.e-rna.org/r-chie/images/single.png

[Brandon Hurr]

I'll happily be wrong, but out of the box I'm going to go with no. 

You could certainly make a plot very similar to this relying heavily on grid. Draw circles, draw x-axis, cut plot off below x-axis... 

I do question how useful this plot is though... I can't figure out what sort of data the size of the arc represents. Wider arcs seem to be more visually weighted. Whether that is good or not is dependent upon the data and what you are trying to communicate. 

On Fri, Sep 21, 2012 at 9:10 AM, gireesh bogu <girees...@gmail.com> wrote:

Is it possible to draw something like this using ggplot ?

www.e-rna.org/r-chie/images/single.png

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[gireesh bogu]

Dear Brandon,

Arc plotting, It is one of the advance method to connect complex data points. You can get a sense by looking at this plot

http://mbostock.github.com/protovis/ex/arc.html

[Brandon Hurr]

There is a grob for doing the arcs https://svn.r-project.org/R/trunk/src/library/grid/man/grid.curve.Rd

And Baptiste suggested a geom_arc() here: http://stackoverflow.com/questions/11641356/circular-plot-in-ggplot2-with-line-segments-connected-in-r

But I don't think this has happened. 

You could spend the time to make a geom_arc().  It wouldn't be easy, but this is certainly possible. 

B

[Osmo Salomaa]

Since those arcs seem to be half-circles, the answer to "How to draw an arc from one point to another using ggplot" is that if you know the two points you can easily (couple lines of code) generate the points to represent the arc using a sequence of angles seq(pi, 0, length.out=100) and basic trigonometry and draw them using geom_path. If you need to do some grouping or ordering of points with no natural coordinates (which your protovis link seems to imply), then it's more difficult.