Hi
I'm writing a small script to plot my data, and I'd like to use a command
line option to allow the same plot to be either displayed with GTK or
output to postscript.
This means I have to switch matplotlib backends within the script.
Now by the time I know what option the user has chosen, I'm in a function:
def plotThings(options):
matplotlib.use(options.plotbackend)
from matplotlib.matlab import *
plot(...)
...
and python complains
SyntaxWarning: import * only allowed at module level
It still works, but I think I'm on thin ice. And it doesn't work if I do:
def main():
# ... parse options ...
matplotlib.use(options.plotbackend)
from matplotlib.matlab import *
plotThings(options)
SyntaxWarning: import * only allowed at module level
NameError: global name 'plot' is not defined
The matplotlib docs say you need to specify the backend before importing
matplotlib.matlab. But this seems a bit restrictive: what if I want to
display a plot on screen, and then output the same plot to postscript and
print it? Normally imports are done only once at the top of a file, but
I'd like to be able to switch backends anywhere.
What are your thoughts on this issue?
I've been using matplotlib for a while. It's the best python plotting tool
I reckon. Thanks for contributing to free software.
Cheers and thanks,
Matthew.
Well I just answered my own question. As the docs point out, you can use
the -dPS option to turn on the postscript backend. So to use this in
harmony with my scripts I needed to:
a) break out the plotting into a separate application called using command
line options (conveniently I had already done this)
b) tell my option parser about the -d option:
import matplotlib
from matplotlib.matlab import *
# ...
def main():
# ...
parser.add_option("-d", dest="plotbackend", default="GTK",
choices=matplotlib._knownBackends.keys(),
help="Graphics backend to use to generate plots.")
# ...
c) use options.plotbackend in my own code to tell whether to
savefig('something.ps')
It's a bit awkward, but workable.
Cheers,
Matthew.
···
On Mon, 5 Jan 2004, matthew arnison wrote:
Hi
I'm writing a small script to plot my data, and I'd like to use a command
line option to allow the same plot to be either displayed with GTK or
output to postscript.
This means I have to switch matplotlib backends within the script.
Now by the time I know what option the user has chosen, I'm in a function:
def plotThings(options):
matplotlib.use(options.plotbackend)
from matplotlib.matlab import *
plot(...)
...
and python complains
SyntaxWarning: import * only allowed at module level
It still works, but I think I'm on thin ice. And it doesn't work if I do:
def main():
# ... parse options ...
matplotlib.use(options.plotbackend)
from matplotlib.matlab import *
plotThings(options)
SyntaxWarning: import * only allowed at module level
NameError: global name 'plot' is not defined
The matplotlib docs say you need to specify the backend before importing
matplotlib.matlab. But this seems a bit restrictive: what if I want to
display a plot on screen, and then output the same plot to postscript and
print it? Normally imports are done only once at the top of a file, but
I'd like to be able to switch backends anywhere.
What are your thoughts on this issue?
I've been using matplotlib for a while. It's the best python plotting tool
I reckon. Thanks for contributing to free software.
Cheers and thanks,
Matthew.
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