matplotlib-users

[Matplotlib-users] How to run matplotlib in batch mode to generate plot image files

[Vineet J. <vi...@al...>]

1. I added the following at the end of the script just before show

savefig("filename")

It works however the intereactive mode still comes up. How can I generate
the image file without having the interactive window come up.

2. figure(1, facecolor=figBG)
What is this used for? Is it for the interactive charting? I can still
generate charts to file with this commented.

3. Where and how do you set the overall size of the chart ( in inches or
pixels)

Thanks,

Vineet

Re: [Matplotlib-users] How to run matplotlib in batch mode to generate plot image files

[John H. <jdh...@ac...>]

>>>>> "Vineet" == Vineet Jain <vi...@al...> writes:

    Vineet> 1. I added the following at the end of the script just
    Vineet> before show savefig("filename")

    Vineet> It works however the intereactive mode still comes up. How
    Vineet> can I generate the image file without having the
    Vineet> interactive window come up.

Hi Vineet,

This is because you are using the TkAgg backend.  This is the default
backend for win32 users.  You set the default backend in your
.matplotlibrc file, which is located in
C:\python23\share\matplotlib\.matplotlibrc for a standard win32
install.  For pure image generation, you probably want to choose Agg
as the default backend.  There are a number of ways of setting the
backend at runtime, as described at
http://matplotlib.sourceforge.net/backends.html

    Vineet> 2. figure(1, facecolor=figBG) What is this used for? Is it
    Vineet> for the interactive charting? I can still generate charts
    Vineet> to file with this commented.

Here is a little background.  You can use the functions figure,
subplot, and axes to explicitly control this figure and axes creation.
If you don't use them, defaults will be issued for you.  Let's take a
look at what happens under the hood when you issue the commands

  >>> from matplotlib.matlab import *
  >>> plot([1,2,3])

When plot is called, the matlab interface makes a call to gca() "get
current axes" to get a reference to the current axes.  gca in turn,
makes a call to gcf() to get a reference to the current figure.  gcf,
finding that no figure has been created, creates the default figure
with figure() and returns it.  gca will then return the current axes
of that figure if it exists, or create the default axes
subplot(111) if it does not.  Thus the code above is equivalent
to

  >>> from matplotlib.matlab import *
  >>> figure()
  >>> subplot(111)
  >>> plot([1,2,3])

The only time you need to manually call figure, subplot and axes are
when 1) you want to manage multiple figures and axes, or 2) you want
to change the default parameters (sizes, locations, colors, etc).

    Vineet> 3. Where and how do you set the overall size of the chart
    Vineet> ( in inches or pixels)

The figsize kwarg to figure sets the figure size in inches.  The dpi
specifies the dots per inch.  The figure width in pixels is thus the
figsize width component time the dpi.  You can set these as kwargs to
the figure command - see
http://matplotlib.sf.net/matplotlib.matlab.html#-figure or by setting
the defaults in your rc file in the section

  ### FIGURE
  figure.figsize   : 8, 6    # figure size in inches
  figure.dpi       : 80      # figure dots per inch
  figure.facecolor : 0.75    # figure facecolor; 0.75 is scalar gray
  figure.edgecolor : w       # figure edgecolor; w is white

Note that the rc allows different defaults for savefig, which are
given by

  savefig.dpi       : 100      # figure dots per inch
  savefig.facecolor : w        # figure facecolor; 0.75 is scalar gray
  savefig.edgecolor : w        # figure edgecolor; w is white

Cheers,
JDH

RE: [Matplotlib-users] How to run matplotlib in batch mode to generate plot image files

[Vineet J. <vi...@al...>]

Thanks for the information. It has been very helpful. Matplotlib seems to be
ignoring the use command. When I change the value in .matplotlibrc it works
however adding the use('Agg') does not change the backed. Do I need to do
anything else?

Thanks,

Vineet


-----Original Message-----
From: mat...@li...
[mailto:mat...@li...]On Behalf Of John
Hunter
Sent: Tuesday, July 20, 2004 9:15 AM
To: Vineet Jain
Cc: mat...@li...
Subject: Re: [Matplotlib-users] How to run matplotlib in batch mode to
generate plot image files


>>>>> "Vineet" == Vineet Jain <vi...@al...> writes:

    Vineet> 1. I added the following at the end of the script just
    Vineet> before show savefig("filename")

    Vineet> It works however the intereactive mode still comes up. How
    Vineet> can I generate the image file without having the
    Vineet> interactive window come up.

Hi Vineet,

This is because you are using the TkAgg backend.  This is the default
backend for win32 users.  You set the default backend in your
.matplotlibrc file, which is located in
C:\python23\share\matplotlib\.matplotlibrc for a standard win32
install.  For pure image generation, you probably want to choose Agg
as the default backend.  There are a number of ways of setting the
backend at runtime, as described at
http://matplotlib.sourceforge.net/backends.html

    Vineet> 2. figure(1, facecolor=figBG) What is this used for? Is it
    Vineet> for the interactive charting? I can still generate charts
    Vineet> to file with this commented.

Here is a little background.  You can use the functions figure,
subplot, and axes to explicitly control this figure and axes creation.
If you don't use them, defaults will be issued for you.  Let's take a
look at what happens under the hood when you issue the commands

  >>> from matplotlib.matlab import *
  >>> plot([1,2,3])

When plot is called, the matlab interface makes a call to gca() "get
current axes" to get a reference to the current axes.  gca in turn,
makes a call to gcf() to get a reference to the current figure.  gcf,
finding that no figure has been created, creates the default figure
with figure() and returns it.  gca will then return the current axes
of that figure if it exists, or create the default axes
subplot(111) if it does not.  Thus the code above is equivalent
to

  >>> from matplotlib.matlab import *
  >>> figure()
  >>> subplot(111)
  >>> plot([1,2,3])

The only time you need to manually call figure, subplot and axes are
when 1) you want to manage multiple figures and axes, or 2) you want
to change the default parameters (sizes, locations, colors, etc).

    Vineet> 3. Where and how do you set the overall size of the chart
    Vineet> ( in inches or pixels)

The figsize kwarg to figure sets the figure size in inches.  The dpi
specifies the dots per inch.  The figure width in pixels is thus the
figsize width component time the dpi.  You can set these as kwargs to
the figure command - see
http://matplotlib.sf.net/matplotlib.matlab.html#-figure or by setting
the defaults in your rc file in the section

  ### FIGURE
  figure.figsize   : 8, 6    # figure size in inches
  figure.dpi       : 80      # figure dots per inch
  figure.facecolor : 0.75    # figure facecolor; 0.75 is scalar gray
  figure.edgecolor : w       # figure edgecolor; w is white

Note that the rc allows different defaults for savefig, which are
given by

  savefig.dpi       : 100      # figure dots per inch
  savefig.facecolor : w        # figure facecolor; 0.75 is scalar gray
  savefig.edgecolor : w        # figure edgecolor; w is white

Cheers,
JDH


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Re: [Matplotlib-users] How to run matplotlib in batch mode to generate plot image files

[John H. <jdh...@ac...>]

>>>>> "Vineet" == Vineet Jain <vi...@al...> writes:

    Vineet> Thanks for the information. It has been very
    Vineet> helpful. Matplotlib seems to be ignoring the use
    Vineet> command. When I change the value in .matplotlibrc it works
    Vineet> however adding the use('Agg') does not change the
    Vineet> backed. Do I need to do anything else?

You must use the use command before importing matplotlib.matlab, as
described on http://matplotlib.sourceforge.net/backends.html

  >>> import matplotlib
  >>> matplotlib.use('Agg')
  >>> from matplotlib.matlab import *

Note that if you are using an IDE like pycrust, pythonwin, or IDLE,
matplotlib.matlab may have already been loaded, and subsequent calls
to use or 'from matplotlib.matlab import *' will have no effect unless
you explicitly force a module reload.

JDH