If you want high performance with a minimal code footprint, look no farther than Python’s built-in plotting library tkinter. No need to write special C / C++ code or use a large plotting package to get performance much better than 50 fps.
The following code scrolls a 1000×200 strip chart at 400 fps on a 2.2 GHz Core 2 duo, 1000 fps on a 3.4 GHz Core i3. The central routine “scrollstrip” plots a set of data points and corresponding colors at the right edge along with an optional vertical grid bar, then scrolls the stripchart to the left by 1. To plot horizontal grid bars just include them in the data and color arrays as constants along with your variable data points.
from tkinter import *
import math, random, threading, time
class StripChart:
def __init__(self, root):
self.gf = self.makeGraph(root)
self.cf = self.makeControls(root)
self.gf.pack()
self.cf.pack()
self.Reset()
def makeGraph(self, frame):
self.sw = 1000
self.h = 200
self.top = 2
gf = Canvas(frame, width=self.sw, height=self.h+10,
bg="#002", bd=0, highlightthickness=0)
gf.p = PhotoImage(width=2*self.sw, height=self.h)
self.item = gf.create_image(0, self.top, image=gf.p, anchor=NW)
return(gf)
def makeControls(self, frame):
cf = Frame(frame, borderwidth=1, relief="raised")
Button(cf, text="Run", command=self.Run).grid(column=2, row=2)
Button(cf, text="Stop", command=self.Stop).grid(column=4, row=2)
Button(cf, text="Reset", command=self.Reset).grid(column=6, row=2)
self.fps = Label(cf, text="0 fps")
self.fps.grid(column=2, row=4, columnspan=5)
return(cf)
def Run(self):
self.go = 1
for t in threading.enumerate():
if t.name == "_gen_":
print("already running")
return
threading.Thread(target=self.do_start, name="_gen_").start()
def Stop(self):
self.go = 0
for t in threading.enumerate():
if t.name == "_gen_":
t.join()
def Reset(self):
self.Stop()
self.clearstrip(self.gf.p, '#345')
def do_start(self):
t = 0
y2 = 0
tx = time.time()
while self.go:
y1 = 0.2*math.sin(0.02*math.pi*t)
y2 = 0.9*y2 + 0.1*(random.random()-0.5)
self.scrollstrip(self.gf.p,
(0.25+y1, 0.25, 0.7+y2, 0.6, 0.7, 0.8),
( '#ff4', '#f40', '#4af', '#080', '#0f0', '#080'),
"" if t % 65 else "#088")
t += 1
if not t % 100:
tx2 = time.time()
self.fps.config(text="%d fps" % int(100/(tx2 - tx)))
tx = tx2
# time.sleep(0.001)
def clearstrip(self, p, color): # Fill strip with background color
self.bg = color # save background color for scroll
self.data = None # clear previous data
self.x = 0
p.tk.call(p, 'put', color, '-to', 0, 0, p['width'], p['height'])
def scrollstrip(self, p, data, colors, bar=""): # Scroll the strip, add new data
self.x = (self.x + 1) % self.sw # x = double buffer position
bg = bar if bar else self.bg
p.tk.call(p, 'put', bg, '-to', self.x, 0,
self.x+1, self.h)
p.tk.call(p, 'put', bg, '-to', self.x+self.sw, 0,
self.x+self.sw+1, self.h)
self.gf.coords(self.item, -1-self.x, self.top) # scroll to just-written column
if not self.data:
self.data = data
for d in range(len(data)):
y0 = int((self.h-1) * (1.0-self.data[d])) # plot all the data points
y1 = int((self.h-1) * (1.0-data[d]))
ya, yb = sorted((y0, y1))
for y in range(ya, yb+1): # connect the dots
p.put(colors[d], (self.x,y))
p.put(colors[d], (self.x+self.sw,y))
self.data = data # save for next call
def main():
root = Tk()
root.title("StripChart")
app = StripChart(root)
root.mainloop()
main()