Below is an annotated version of the script polymark.jnl:
Note that in PyFerret, similar plots may be drawn using the PLOT/RIBBON command and filled symbols. The second plot using squares would be duplicated with a PLOT/VS/RIBBON/SYMBOL=boxfill command and /HIGHLIGHT to outline the symbols. This renders much faster than the outlined polygons drawn in the last example below.
yes? GO basemap x=120:250 Y=25s:65n 20 yes? ribbon/over/vs/SYBMOL=boxfill/HIGHLIGHT/siz=0.15/key/title="SST" xpts,ypts,sst
Make a base map to show the location, and plot (lat,lon,sst) triples to color the locations according to SST on the map.
yes? ! Open demo ship track file with Lat, Lon, and SST yes? use polydata yes? ! polymark needs an underlying plot to define scaling yes? go basemap x=130:250 Y=20:65 20 yes? go polymark poly/over/key/title="SST along track" lon lat sst star
! list the available shapes: yes? go/help polyshape Full path name: /home/users/tmap/ferret/rhel6-x86_64-linux/go/polyshape.jnl \cancel mode verify ! polyshape.jnl ! ... ! Description: define xpolyshape, ypolyshape variables for polygon fills ! usage: ! GO polyshape shape_name ! shape names include: ! triangle delta square ! diamond pentagon hexagon ! circle star plus ! ex rectangle tallbox ! hletter lletter ! trianglec deltac exc ! rectanglec tallboxc fslash ! bslash tletter tupside ! tleft tright vright ! vleft rtriangle ltriangle ! uright uleft yes? go basemap x=130:250 Y=20:65 20 yes? go polymark poly/over/key/line/fill/lev=(1,9,1)/title="Smaller & outline" lon lat sst square .6
Or a pattern fill (Ferret only; Pyferret does not have pattern fill as of version 7)
! Use a square in a pattern & outline yes? go basemap x=130:250 Y=20:65 20 yes? go polymark poly/over/key/pattern=4patterns/palette=black/line/fill/lev=(1,9,2)/title="Using patterns" lon[i=3:37:2] lat[i=3:37:2] sst[i=3:37:2] square 1.75