[GRASSLIST:8454] Controlling pie chart orientation in d.vect.chart

GRASS GRASS user
1

Hey guys,

I've noticed that when I plot a series of sediment grainsize pie charts in
d.vect.chart, the first attribute field I specify under the columns
parameter gets painted into the first pie chart chord (which begins at
orientation 90 degrees east), and the subsequent fields are filled
counterclockwise around the pie chart. Is there a way to control the
orientation of the chart so that, say, the first field is coloured at north,
progressing clockwise?

Thanks,

~ Eric.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Eric Patton

Technologist, Geo-Spatial Data Services
Geological Survey of Canada (Atlantic)
Natural Resources Canada
Bedford Institute of Oceanography
Dartmouth, Nova Scotia, Canada B2Y 4A2

Postal address: P.O. Box 1006
Courier address: 1 Challenger Drive

Telephone: (902)426-7732
Facsimile: (902)426-4104
E-mail: <mailto:epatton@NRCan.gc.ca> epatton@NRCan.gc.ca

2

I've noticed that when I plot a series of sediment grainsize pie
charts in d.vect.chart, the first attribute field I specify under the
columns parameter gets painted into the first pie chart chord (which
begins at orientation 90 degrees east), and the subsequent fields are
filled counterclockwise around the pie chart. Is there a way to
control the orientation of the chart so that, say, the first field is
coloured at north, progressing clockwise?

well you'd have to change the source code; in general to go from polar
coordinate angles to compass angles replace theta with 90-theta,
possibly followed by a

if(theta < 0) theta=theta+360;

step.

Hamish