Re: [Matplotlib-users] clipping feature?

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

>>>>> "James" == James Boyle <bo...@ll...> writes:

    James> I set the axis bounds when I am plotting a number of lines
    James> some of which have a larger domain. While interested in the
    James> behaviour in the limited domain, I would like to retain the
    James> information that some lines extend beyond.  When I first
    James> encountered this behaviour, I thought that I had mistakenly
    James> truncated my input data - I think that the plot should show
    James> as much of the data passed to it as possible.

    James> Is there something I am missing - or is this a feature?

It's a feature!

matplotlib does two kinds of clipping: data clipping and viewport
clipping.  Viewport clipping is the typical clipping where the lines
are clipped to the viewport.  data clipping throws out all points not
in the viewport.

I work with very long data sets of which only a small portion is in
the viewport, and use the interactive navigation controls to scroll
trough it.  I found it was much more efficient to first clip the data
with Numeric before plotting it.  See examples/stock_demo.py, of which
only a few days of 60 days of data are initially in the viewport.

You can control this in a couple of ways:

    from matplotlib.matlab import *
    ax = subplot(111)
    line1, line2 = plot([1,2,3,4],'bo', [1,2,3,4],'k')
    line1.set_data_clipping(False)
    line2.set_data_clipping(False)
    axis([0.,2.4,1.,4.])
    show()

Or edit the init function of lines.Line2D to turn data clipping off by
default

        self._useDataClipping = False

I've been meaning to make a matplotlibrc file to control things like
default line width, color, fontsize and name, antialiasing, data
clipping and so on.

JDH