On Tue, Dec 20, 2011 at 8:00 AM, Nils Wagner
<nwag...@iam.uni-stuttgart.de>wrote:
> Hi all,
>
> How do I use animation.FuncAnimation to plot real-life
> data from parsing a text file ?
>
>
> import numpy as np
> import matplotlib.pyplot as plt
> import matplotlib.animation as animation
>
> import sys
> import time
> import re
>
> x = [] # x
> y = [] # y
>
> fig = plt.figure()
> ax = fig.add_subplot(111)
> curve,= ax.plot([],[],lw=2)
> ax.set_xlim(0,5)
> ax.grid()
>
> def tail_f(file):
> interval = 1.0
>
> while True:
> where = file.tell() # current file position, an
> integer (may be a long integer).
> line = file.readline()
> if re.search('without errors',line): break
> if not line:
> time.sleep(interval)
> file.seek(where) # seek(offset[, whence]) ->
> None. Move to new file position.
> else:
> yield line
>
>
> def run():
> for line in tail_f(open(sys.argv[1])):
> print line,
> if re.search('x=',line):
> liste = line.split('=')
> x.append(liste[1].strip())
> if re.search('y=',line):
> liste = line.split('=')
> y.append(liste[1].strip())
>
> curve.set_data(x,y)
> print x,y
> #
> #
> #
> run()
> plt.show()
>
>
> The text file looks like
>
> x=0.0
> y=0.0
> blabla
> x=1.0
> y=1.0
> blabla
> x=2.0
> y=4.0
> blabla
> ...
>
>
>
> Nils
>
>
Nils,
I think the key thing to keep in mind when using any of the animators is
that the animator in question is driving the calls to update the plot from
its own event source. In most cases, that source is a timer. For
FuncAnimator, the function passed into the constructor must perform
whatever actions are needed for a single update.
What I would do is Subclass FuncAnimator so that its constructor will
create an empty Line2D object that has already been added to an axes object
(or you can pass an empty one yourself as an argument to the function). In
the function run(), you would obtain the next chunk of data and then update
the Line2D object with that information.
I think you have it mostly done, just need a few extra pieces.
Cheers!
Ben Root
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