Gnuplot [updated]

May 25, 2010 at 3:01 pm 2 comments

| Gabriel |

Here’s an updated version of my old script for piping from Stata to Gnuplot. Gnuplot is a generic graphing utility. The main thing it can do that Stata can’t is good 3D graphs. (Although the ado files “surface” and “tddens” make a good effort at adding this capability). In this version I set it to a coarser smooth, set the horizontal plane to the minimum value for Z, and allow either contour or surface.

Note that the dgrid3d smoothing algorithm in Gnuplot 4.2 (which is still the version maintained in Fink and Ubuntu) has some problems — the most annoying of which is that it can go haywire at the borders. I decided to handle this by setting it to a coarse smooth (5,5,1). However if unlike me you’re lucky enough to have Gnuplot 4.3 you have access to several much better smoothing algorithms and you may want to experiment with increasing the resolution and using one of the new algorithms by editing line 41 of this script.

*GHR 5/25/2010
*gnuplotpm3d 1.1
*pipes data to gnuplot's splot command, useful for color surface graphs
capture program drop gnuplotpm3d
program define gnuplotpm3d
syntax varlist(min=3 max=3 numeric) [ , title(string asis) xlabel(string asis) ylabel(string asis) using(string asis) contour rotate(string asis)]

disp "`rotate'"

if "`xlabel'"=="" {
local xlabel="`x'"
if "`ylabel'"=="" {
local ylabel="`y'"
tempfile gnuplotpm3cmd
tempfile data

keep `varlist'
order `varlist'
disp "`using'"
outsheet using `data'.txt

*assumes that the software is running on a mac using
*if installed with fink or macports, set to the default (Unix) mode of just "gnuplot"
local gnuplot="gnuplot"
if "`c(os)'"=="MacOSX" {
	local gnuplot="exec '/Applications/'"  /*assumes binary install, set to simply "gnuplot" if fink or macports install*/
if "`c(os)'"=="Windows" {
	*not tested
	local gnuplot="gnuplot.exe"  

file open gpcmd using `gnuplotpm3cmd', write text
file write gpcmd "cd '`c(pwd)'' ; " _n
file write gpcmd "set terminal postscript color ; set output '`using'.eps' ; set palette color positive ; " _n
file write gpcmd "set auto ; set parametric ; " _n
file write gpcmd "set dgrid3d 5,5,1 ; " _n  /*interpolation algorithm, allows tolerance for data irregularities -- set to low numbers for smooth graph and high numbers for bumpier graph*/
file write gpcmd `"set title "`title'" ; set ylabel "`ylabel'"; set xlabel "`xlabel'"; "' _n
file write gpcmd "unset contour; unset surface; " _n
if "`contour'"=="contour" {
	file write gpcmd "set view map; " _n
if "`rotate'"!="" & "`contour'"=="contour" {
	file write gpcmd "set view `rotate'; " _n
if "`contour'"=="contour" & "`rotate'"!="" {
	disp "rotate options ignored as they are incompatible with contour view"
file write gpcmd "set xyplane 0; " _n  /*put the xy plane right at min(z) */
file write gpcmd "set pm3d;" _n
file write gpcmd "set pm3d interpolate 10,10; " _n
file write gpcmd `"splot "`data'.txt"; "' _n
file close gpcmd

shell `gnuplot' `gnuplotpm3cmd'

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