Re: [Matplotlib-users] Labels in a dynamic graph
Hello Amit,
On Sunday 23 March 2008 09:54, Amit Finkler wrote:
Hi everyone,
I am using matplotlib to dynamically plot a graph with both my x and y
points taken from a measurement device. That is to say, in each
iteration of my while loop I'm reading two variables which I then want
to plot with matplotlib.
I wrote something which goes like this (disregard the Gnuplot - that's
what I'm trying to replace with matplotlib...)
import gpib, Numeric, time, Gnuplot, mymodule, threading
from pylab import *
def cooldown(filename, dmm_gpib, lake_gpib):
this program scans dummy and reads HP and Lakeshore
A = Numeric.arange(-1, 1, .1)
delay = 1
f = open(filename,'w')
X = []
Y = []
figure(2)
hold(False)
try:
while A[0]10:
gpib.write(lake_fd, 'SDAT?')
gpib.write(hp_fd, 'read?')
time.sleep(delay)
val1 = float(gpib.read(lake_fd, 30))
val2 = float(gpib.read(hp_fd, 30))
X.append(val1)
Y.append(val2)
plot(X,Y,'.-')
f.write(str(val1) + '\t' + str(val2) + '\n')
f.flush()
I'm running this code in ipython with the -pylab option, so I don't need
to use show(). My question is, how do I maintain a *constant* xlabel and
ylabel without having to redraw them each time I append a point to the
graph? If I try xlabel('something') then obviously it's cleared each
time I use plot(X,Y).
I'm not sure I understand well, but if one uses xlabel(something) before the
while-loop or just after building the figure, it is not redrawn after
plotting.
regards
Matthias
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Re: [Matplotlib-users] Labels in a dynamic graph
On Sun, Mar 23, 2008 at 3:54 AM, Amit Finkler [EMAIL PROTECTED] wrote:
I am using matplotlib to dynamically plot a graph with both my x and y
points taken from a measurement device. That is to say, in each iteration of
my while loop I'm reading two variables which I then want to plot with
matplotlib.
You will want to do something like (this is just a sketch)
xdata = []
ydata = []
fig = figure()
ax = fig.add_subplot(111)
ax.set_xlabel('my xlabel')
ax.set_ylabel('my ylabel')
line, = ax.plot(xdata, ydata)
def add_point(x, y):
xdata.append(x)
ydata.append(y)
if len(xdata)30: # optional, prune the early points
del xdata[0]
del ydata[0]
xmin = xdata[0]
xmax = xdata[-1]
line.set_data(xdata, ydata)
ax.set_xlim(xmin, xmax)
fig.canvas.draw()
while 1:
x,y = get_data_point()
add_point(x, y)
JDH
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Re: [Matplotlib-users] Labels in a dynamic graph
John Hunter wrote:
On Sun, Mar 23, 2008 at 3:54 AM, Amit Finkler [EMAIL PROTECTED] wrote:
I am using matplotlib to dynamically plot a graph with both my x and y
points taken from a measurement device. That is to say, in each iteration of
my while loop I'm reading two variables which I then want to plot with
matplotlib.
You will want to do something like (this is just a sketch)
xdata = []
ydata = []
fig = figure()
ax = fig.add_subplot(111)
ax.set_xlabel('my xlabel')
ax.set_ylabel('my ylabel')
line, = ax.plot(xdata, ydata)
def add_point(x, y):
xdata.append(x)
ydata.append(y)
if len(xdata)30: # optional, prune the early points
del xdata[0]
del ydata[0]
xmin = xdata[0]
xmax = xdata[-1]
line.set_data(xdata, ydata)
ax.set_xlim(xmin, xmax)
fig.canvas.draw()
while 1:
x,y = get_data_point()
add_point(x, y)
JDH
John,
Thanks for getting back to me. Indeed this works, at least when I try it
line by line. When I inserted it into my module, it shot back some error
message which goes like this:
File
/usr/lib/python2.4/site-packages/matplotlib/backends/backend_tkagg.py,
line 154, in draw
FigureCanvasAgg.draw(self)
File
/usr/lib/python2.4/site-packages/matplotlib/backends/backend_agg.py,
line 392, in draw
self.figure.draw(renderer)
File /usr/lib/python2.4/site-packages/matplotlib/figure.py, line
544, in draw
for a in self.axes: a.draw(renderer)
File /usr/lib/python2.4/site-packages/matplotlib/axes.py, line
1004, in draw
try: self.transData.freeze() # eval the lazy objects
ValueError: Domain error on eval_scalars in Transformation::freeze
Since it did work on the console, i.e., line by line, I think it's only
a matter of resolving my own source code, unless of course you think
otherwise. By the way, isn't there a way to do the set_xlim/ylim
automatically? When I use only figure(), hold(False) and plot(X, Y), it
updates it automatically, so why doesn't it do it with the subplot?
Thanks for your help.
Amit.
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Re: [Matplotlib-users] Labels in a dynamic graph
On Tue, Mar 25, 2008 at 11:39 AM, Amit Finkler [EMAIL PROTECTED] wrote: I am using matplotlib to dynamically plot a graph with both my x and y points taken from a measurement device. That is to say, in each iteration of my while loop I'm reading two variables which I then want to plot with matplotlib. Odd, are you using an older version of matplotlib (it works for me). Try seeding your data with an initial point xdata = [x] ydata = [y] or setting the axis limits before plotting ax.set_xlim(0,1) ax.set_ylim(0,1) Not sure why you are having problems JDH - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
