SciPy Plt Plotting Intro

SciPy is a library of scientific tools for Python. It has a large user base, and is growing rapidly.

Before continuing, ensure that SciPy is installed. Prerequisites are Python, the Numeric module, and (for plt) wxPython. On the Windows platform, installation is quite easy with self-installing exe packages. On Linux, it's no more complicated that the usual package. In some cases, rpm and deb packages exist. ( I didn't use them.)

You really should read the short plotting tutorial, one of several tutorials available. There are at least three plotting routines available for scipy. Since plt is available for both Unix and Windows, I'll discuss that.

Here's a typical example of how to display data with 'plt':

            # import the necessary modules
            >>> import gui_thread
            <wxPython imported>

            >>> from scipy import *
            >>> from scipy import plt

            # create some data to plot
            >>> x = [1,2,3,4]
            >>> y = [1,4,9,16]
            >>> plt.plot(x,y)
            [ a graphics window should appear ]

            # now add some titles
            >>> plt.xtitle('x axis')
            >>> plt.ytitle('y axis')

(You change also add text from the Titles menu; or change text, fonts, and sizes by right-clicking on the labels and title. You can zoom by dragging with the left button, and autozoom out with a right-click.)

The following generates a "image plot" or "density plot":

            >>> x=(arange(100.)-50)/2.
            >>> y=(arange(100.)-50)/2.
            >>> r = sqrt(x[:,NewAxis]**2+y**2)
            >>> z = r**2
            >>> plt.image(z)

            >>> print min(ravel(z)), max(ravel(z))

            >>> plt.imagesc(z)

Feel free to e-mail me with any questions about this document.