GWM Based on A Little graph Plotter. See also Fun with Functions, Another Graphing Widget.
Corrected May 2006 for missing proc.
Modified to draw a set of points or multiple sets of points on a canvas. The proc plot takes a list of data to be plotted and a set of titles (one per graph). The data format is: [list of xposition [list of ypositions (1,2 or more)]]] eg:
set res [0.0 {0.0 1.0} 0.333 {0.327 0.944 } 0.6667 {0.618 0.785}]
will define 3 points at x = 0, .333, .6667 with 2 y coordinates per x position (2 graphs). Better example data at the end of this page.
package require math
proc graphscale {v vmin vmax pixels} {
return [expr {$pixels*($v-$vmin)/($vmax-$vmin)}]
}
proc plot {res titles} { ;# adapted the simple graph plotter found on http://wiki.tcl.tk/8552
# --------------------------
# params
# --------------------------
# title
# canvas width & height
array set params \
{
title {Graph}
width 400
height 400
}
# canvas
if [winfo exists .c] { ;# delete it. Same as clear.
destroy .c
}
canvas .c -width $params(width) -height $params(height) \
-xscrollincrement 1 -bg beige
pack .c
wm title . $params(title)
# get range of x & y
set xmin 100000000
set xmax -100000000
set ymin 100000000
set ymax -100000000
set vv0 [lindex $res 1]
set nvars [llength $vv0]
foreach {r y} $res {
set xmin [::math::min $xmin $r]
set xmax [::math::max $xmax $r]
foreach yv $y { ;# get range of Y coordinate
set ymin [::math::min $ymin $yv]
set ymax [::math::max $ymax $yv]
}
}
#how often tick marks
set tspace [expr ($xmax-$xmin)/8.0] ;# how often to draw grid in X
set nexttic [expr int($xmin/$tspace)*$tspace]
foreach {r y} $res { ;# draw grid
if {$r >= $nexttic} {
set xpix [graphscale $nexttic $xmin $xmax $params(width)]
set nexttic [expr $nexttic+$tspace]
.c create text [expr $xpix-10] 0 -anchor n -text $r -fill gray
.c create line $xpix 0 $xpix $params(height) -fill gray
}
}
#how often Ytick marks
set tspace [expr ($ymax-$ymin)/8.0] ;# how often to draw grid in X
set nexttic [expr int($ymin/$tspace)*$tspace]
while {$nexttic < $ymax} { ;# draw grid
set ypix [graphscale $nexttic $ymax $ymin $params(height)]
set nexttic [expr $nexttic+$tspace]
.c create text 10 [expr $ypix-10] -anchor n -text $nexttic -fill gray
.c create line 0 $ypix $params(width) $ypix -fill gray
}
#label graphs
.c create text 20 10 -anchor n -text [lindex $titles 0] -fill red
.c create text 20 25 -anchor n -text [lindex $titles 1] -fill black
for {set iy 0} {$iy<$nvars} {incr iy} {
set color "black"
if {$iy==1} {set color "red"}
if {$iy==2} {set color "green"}
set coordlist {}
foreach {r y} $res {
set xpix [graphscale $r $xmin $xmax $params(width)]
set vv [lindex $y $iy]
set v [graphscale $vv $ymax $ymin $params(height)]
lappend coordlist $xpix $v
set rold $xpix
set yold $v ;# vector of y values
}
.c create line $coordlist -fill $color
}
update
}
# Exercise the graph thus:
set plot {}
for {set i 0} {$i<20} {incr i} { lappend plot [expr $i/3.0] [expr sin($i/3.0)]}
plot $plot "Sine"
# Or 2 graphs (values of sin(x) and cos(x) are placed in a list of results at x):
set plot {}
for {set i 0} {$i<20} {incr i} { lappend plot [expr $i/3.0] [list [expr sin($i/3.0)] [expr cos($i/3.0)]]}
plot $plot {"Sine" "Cos"}DPO - In the plot proc above, there is a call to a "scale" command. This does not match the tk usage which requires a path as the first arg. What "scale" command is this? It fails for me. (I am forced to use tcl 8.0.5 due to API limitations)
GWM Sorry, a bit slow to respond here... supplied new function graphscale and renamed old proc scale to graphscale. This works a bit better.