[GRASS5] d.polar using d.graph

[Hamish]

Markus wrote:
> The d.polar is waiting for a volunteer to change the xgraph
> dependency to GRASS' d.graph. Maybe done in a few minutes for someone
> who knows the syntax of d.graph input... The xgraph input
> is just a title and coordinate pairs to draw the polar
> diagram.


well, here's a proof of concept; messy, but it does plot something--

`cat` and $FOO in d.graph's stdin is the required magic..

I've done it after-the-fact, but factoring x,y to 0-100% could be done 
right in the "sin()*r, cos()*r" step to save time & space.

notes:
my 1000x1000 aspect grid made 50mb temp files!

I got weird output when trying from r.slope.aspect (elev from 
r.surf.contour). Spikes every 45degree. I thought I had my awk
wrong.. [d.histogram of it attached]. Probably an artifact of blocky
r.surf.contour output? That histogram is interesting.. smaller peaks
22.5deg out of phase with the 45deg spikes..? odd.

Is 0deg north-up or does it have to be rotated?  angle_n_up = 90-theta

The script could use lots of optimization.. move $2*$3/$4 stuff into one 
coefficient before running awk, etc., e.g.
  echo "\"All Data incl. NULL"           > ${TMP}_outercircle
  RADIUS_COEFF=`echo "$TOTALNUMBER $TOTALVALIDNUMBER $MAXRADIUS" | \
     awk '{printf "%.8f", $1/$2 * $3}'`
  for i in `seq 0 360` ; do
    echo "$i $RADIUS_COEFF" | awk ...


The following doesn't honour the undef= option, is it on purpose?
 # unit vector on raw data converted to radians without no data:
 cat ${TMP}_raw | grep -v '^*'| awk 'BEGIN {sum = 0.0}



d.polar code follows (insert at end of script before cleanup)
---------------------

RING=0.95  # percent of frame to use
cat ${TMP}_sine_cosine_replic | tail +2 | awk -v RING=$RING -v MAX=$MAXRADIUS \
    '{printf "%f %f\n", (($1 / MAX * RING) +1)*50, (($2 / MAX * RING)+1)*50}' \
       > ${TMP}_sine_cosine_replic_normalized

VECT=`cat ${TMP}_vector | tail -n 1 | awk -v RING=$RING -v MAX=$MAXRADIUS \
    '{printf "%f %f\n", (($1 / MAX * RING) +1)*50, (($2 / MAX * RING)+1)*50}'`

#d.erase
d.graph << EOF
  # draw the goods
  color red
  polygon
   `cat ${TMP}_sine_cosine_replic_normalized`

  # draw axes
  color black
  width 0
  move 0 50
  draw 100 50
  move 50 0
  draw 50 100

  # draw circle
  #   mandatory! as drawing is proportional to non-square frame

  # draw vector
  color green
  width 2
  move 50 50
  draw $VECT

  # draw compass text
  color black
  width 2
  move 50.5 95
  text N
#  move 50.5 1
#  text S
#  move 1 50.5
#  text W
#  move 95 50.5
#  text E
EOF



Hamish
-------------- next part --------------
A non-text attachment was scrubbed...
Name: aspect_spike.png
Type: image/png
Size: 6184 bytes
Desc: not available
Url : http://lists.osgeo.org/pipermail/grass-dev/attachments/20060317/e3e0703e/aspect_spike.png