# realtime stripchart $Hz Hz
package require Tk
package require BLT
namespace import blt::*
# vector and stripchart are blt components.
# if you have a vector v, you can update it in realtime with
# v set $list
# init the vectors to a fixed size.
set Hz 200
vector create xvec($Hz) y1vec($Hz) y2vec($Hz)
# fill xvec with 0 .. $Hz-1
xvec seq 0 [expr {$Hz - 1}]
stripchart .s1 -height 2i -width 8i -bufferelements no
stripchart .s2 -height 2i -width 8i -bufferelements no
pack .s1 .s2
.s1 element create line1 -xdata xvec -ydata y1vec -symbol none
.s2 element create line2 -xdata xvec -ydata y2vec -symbol none -color red
# update $Hz values with random data once per second
proc proc1sec {} {
# this can be done more concisely with vector random,
# but if you need to fill a vector from scalar calculations,
# do it this way:
for {set i 0} {$i < $::Hz} {incr i} {
lappend y1list [expr {rand()}]
lappend y2list [expr {rand()}]
}
y1vec set $y1list
y2vec set $y2list
after 1000 proc1sec
}
proc1secAndrew Tannenbaum
