Arjen Markus (23 november 2007) Plotchart is very useful for displaying data in plots or charts, but the usual use is rather static: the data come from "somewhere" and are then shown.
The program below shows that it is possible to use it in an interactive way too. The idea is that rather than typing in a lot of numbers in a table, it is easier to click in a window and to see the resulting data series in an xy-plot immediately.
Notes:
# editgraph.tcl --
# Widget to edit data series graphically
#
# Note:
# Not as elegant as could be with bindings via Plotchart itself
#
package require Plotchart
namespace eval ::Editgraph {
variable graph
variable endedit
}
# editSeries --
# Procedure to edit a series of data graphically
#
# Arguments:
# xrange Range for the x values
# yrange Range for the y values
# number Number of data points
#
# Result:
# List of x,y values representing the data series
#
# Note:
# The widget allows setting new y values for given x values only
#
proc ::Editgraph::editSeries {xrange yrange number} {
variable graph
variable endedit
toplevel .graph
wm title .graph "Editing series"
canvas .graph.c -width 400 -height 300
button .graph.ok -text OK -width 10 -command {::Editgraph::SaveSeries}
button .graph.cancel -text Cancel -width 10 -command {::Editgraph::CancelSeries}
grid .graph.c -
grid .graph.ok .graph.cancel
#
# Initialise the series
#
foreach {xmin xmax} $xrange {break}
foreach {ymin ymax} $yrange {break}
if { $ymin <= 0.0 && $ymax >= 0.0 } {
set y 0.0
} else {
set y $ymin
}
set delx [expr {($xmax-$xmin)/double($number-1)}]
set graph(xy) {}
set x $xmin
while { $x < $xmax+0.5*$delx } {
lappend graph(xy) $x $y
set x [expr {$x + $delx}]
if { abs($x) < 0.5 *$delx } {
set x 0.0
}
}
set graph(xmin) $xmin
set graph(xmax) $xmax
set graph(delx) $delx
set graph(number) $number
set graph(plot) [::Plotchart::createXYPlot .graph.c \
[::Plotchart::determineScale $xmin $xmax] \
[::Plotchart::determineScale $ymin $ymax]]
$graph(plot) dataconfig data -colour blue
set graph(widget) .graph.c
foreach {x y} $graph(xy) {
$graph(plot) plot data $x $y
}
#
# Set the bindings
#
# bind .graph.c <Button-1> {::Editgraph::EditPoint %W %x %y}
bind .graph.c <ButtonPress-1> {
::Editgraph::EditPoint %W %x %y
bind %W <Motion> {::Editgraph::EditPoint %W %%x %%y}
}
bind .graph.c <ButtonRelease-1> {
bind %W <Motion> {}
}
vwait ::Editgraph::endedit
puts "$endedit"
if { $endedit == 1 } {
return $graph(xy)
} else {
return {}
}
}
# SaveSeries, CancelSeries --
# Callback procedure for the widget
#
# Arguments:
# None
#
# Result:
# None
#
# Side effects:
# The widget is closed
#
proc ::Editgraph::SaveSeries {} {
set ::Editgraph::endedit 1
destroy .graph
}
proc ::Editgraph::CancelSeries {} {
set ::Editgraph::endedit 0
destroy .graph
}
# EditPoint --
# Callback procedure for setting the new data point
#
# Arguments:
# w Widget
# x X-coordinate of selected point (pixel)
# y Y-coordinate of selected point (pixel)
#
# Result:
# None
#
# Side effects:
# The data points are updated and the graph redrawn
#
proc ::Editgraph::EditPoint {w x y} {
variable graph
foreach {xc yc} [::Plotchart::pixelToCoords $graph(widget) $x $y] {break}
set xp [expr {int(0.5+($xc-$graph(xmin))/$graph(delx))}]
if { $xp < 0 } { set xp 0 }
if { $xp > $graph(number) } { set xp $graph(number) }
lset graph(xy) [expr {2*$xp+1}] $yc
#
# Reset the plotted data
#
$graph(widget) delete data
$graph(plot) plot data "" ""
#
# Redraw the data
#
foreach {x y} $graph(xy) {
$graph(plot) plot data $x $y
}
}
# main --
# Make it all work
catch {
console show
}
set xyseries [::Editgraph::editSeries {0 100} {-50 50} 10]
puts "Series:"
foreach {x y} $xyseries {
puts [format "%10.4f %10.4f" $x $y]
}