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<title>Module: __init__</title>
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width="10%"><font color="#000000">Module: __init__</font>
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<th align="right"><font color="#000000">Gnuplot</font></th>
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<dl><dt>Gnuplot</dt><dd><p>A pipe-based interface to the gnuplot plotting program.</p>
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<p>This is the main module of the Gnuplot package.</p>
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<p>Written by <a href="mailto:mhagger@alum.mit.edu">Michael Haggerty</a>. Inspired
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by and partly derived from an earlier version by <a href="mailto:hinsen@ibs.ibs.fr">Konrad Hinsen</a>. If you find a problem or have a suggestion,
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please <a href="mailto:mhagger@alum.mit.edu">let me know</a>. Other feedback
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would also be appreciated.</p>
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<p>The Gnuplot.py home page is at</p>
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<p><a href="http://gnuplot-py.sourceforge.net">Gnuplot.py</a></p>
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<p>For information about how to use this module:</p>
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<ol><li><p>Check the README file.</p>
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<li><p>Look at the example code in demo.py and try running it by typing
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<code>python demo.py</code> or <code>python __init__.py</code>.</p>
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<li><p>For more details see the extensive documentation strings
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throughout the python source files, especially this file,
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_Gnuplot.py, PlotItems.py, and gp_unix.py.</p>
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<li><p>The docstrings have also been turned into html which can be read
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<a href="http://gnuplot-py.sourceforge.net/doc">here</a>. However, the
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formatting is not perfect; when in doubt, double-check the
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<p>You should import this file with <code>import Gnuplot</code>, not with <code>from
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Gnuplot import *</code>, because the module and the main class have the same
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<p>To obtain the gnuplot plotting program itself, see <a href="ftp://ftp.gnuplot.vt.edu/pub/gnuplot/faq/index.html">the gnuplot FAQ</a>. Obviously you
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need to have gnuplot installed if you want to use Gnuplot.py.</p>
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<p>The old command-based interface to gnuplot has been separated out into
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a separate module, oldplot.py. If you are still using that interface
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you should <code>import Gnuplot.oldplot</code>; otherwise you should stick to the
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more flexible object-oriented interface contained here.</p>
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<ul><li><p>Allows the creation of two or three dimensional plots from
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<li><p>A gnuplot session is an instance of class <code>Gnuplot</code>. Multiple
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sessions can be open at once. For example::</p>
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g1 = Gnuplot.Gnuplot()
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g2 = Gnuplot.Gnuplot()
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Note that due to limitations on those platforms, opening multiple
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simultaneous sessions on Windows or Macintosh may not work
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correctly. (Feedback?)
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<li><p>The implicitly-generated gnuplot commands can be stored to a file
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instead of executed immediately::</p>
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g = Gnuplot.Gnuplot('commands.txt')
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The 'commands.txt' file can then be run later with gnuplot's
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'load' command. Beware, however: the plot commands may depend on
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the existence of temporary files, which will probably be deleted
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before you use the command file.
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<li><p>Can pass arbitrary commands to the gnuplot command interpreter::</p>
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(If this is all you want to do, you might consider using the
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lightweight GnuplotProcess class defined in gp.py.)
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<li><p>A Gnuplot object knows how to plot objects of type <code>PlotItem</code>.
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Any PlotItem can have optional <code>title</code> and/or <code>with</code> suboptions.
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Builtin PlotItem types:</p>
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<ul><li><p><code>Data(array1)</code> -- data from a Python list or NumPy array
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(permits additional option <code>cols</code> )</p>
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<li><p>'File(<code>filename</code>)' -- data from an existing data file (permits
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additional option <code>using</code> )</p>
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<li><p>'Func(<code>exp(4.0 * sin(x))</code>)' -- functions (passed as a string,
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evaluated by gnuplot)</p>
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<li><p><code>GridData(m, x, y)</code> -- data tabulated on a grid of (x,y) values
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(usually to be plotted in 3-D)</p>
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<p> See the documentation strings for those classes for more details.</p>
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<li><p>PlotItems are implemented as objects that can be assigned to
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variables and plotted repeatedly. Most of their plot options can
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also be changed with the new <code>set_option()</code> member functions then
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they can be replotted with their new options.</p>
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<li><p>Communication of commands to gnuplot is via a one-way pipe.
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Communication of data from python to gnuplot is via inline data
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(through the command pipe) or via temporary files. Temp files are
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deleted automatically when their associated <code>PlotItem</code> is deleted.
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The PlotItems in use by a Gnuplot object at any given time are
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stored in an internal list so that they won't be deleted
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<li><p>Can use <code>replot</code> method to add datasets to an existing plot.</p>
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<li><p>Can make persistent gnuplot windows by using the constructor option
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<code>persist=1</code>. Such windows stay around even after the gnuplot
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program is exited. Note that only newer version of gnuplot support
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<li><p>Can plot either directly to a postscript printer or to a
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postscript file via the <code>hardcopy</code> method.</p>
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<li><p>Grid data for the splot command can be sent to gnuplot in binary
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format, saving time and disk space.</p>
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<li><p>Should work under Unix, Macintosh, and Windows.</p>
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<ul><li><p>Relies on the Numeric Python extension. This can be obtained from
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<a href="http://sourceforge.net/projects/numpy/">SourceForge</a>. If you're
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interested in gnuplot, you would probably also want NumPy anyway.</p>
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<li><p>Only a small fraction of gnuplot functionality is implemented as
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explicit method functions. However, you can give arbitrary
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commands to gnuplot manually::</p>
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g = Gnuplot.Gnuplot()
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g('set data style linespoints')
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<li><p>There is no provision for missing data points in array data (which
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gnuplot allows via the <code>set missing</code> command).</p>
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<ul><li><p>No attempt is made to check for errors reported by gnuplot. On
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unix any gnuplot error messages simply appear on stderr. (I don't
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know what happens under Windows.)</p>
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<li><p>All of these classes perform their resource deallocation when
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<code>__del__</code> is called. Normally this works fine, but there are
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well-known cases when Python's automatic resource deallocation
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fails, which can leave temporary files around.</p>
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<i>This document was automatically generated on Fri Jan 26 14:06:11 2001
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