Knowledge Base/Python/matplotlib
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A simple XY plot (procedural approach)
Code:
import math import matplotlib.pyplot import numpy xs = numpy.arange(-math.pi, math.pi, 0.1) ys1 = numpy.sin(xs) ys2 = numpy.cos(xs) matplotlib.pyplot.plot(xs, ys1, "r-", lw=2) matplotlib.pyplot.plot(xs, ys2, "g-", lw=2) matplotlib.pyplot.xlabel("$x$") matplotlib.pyplot.ylabel("$y$") matplotlib.pyplot.title("Trigonometric functions: $\\sin$ and $\\cos$") matplotlib.pyplot.grid(True) matplotlib.pyplot.legend(("$\\sin(x)$", "$\\cos(x)$")) matplotlib.pyplot.show()
A simple XY plot (procedural approach; emulating MATLAB)
We can use Python namespaces in a different way to emulate MATLAB.
Code:
import math import numpy from pylab import * xs = numpy.arange(-math.pi, math.pi, 0.1) ys1 = numpy.sin(xs) ys2 = numpy.cos(xs) plot(xs, ys1, "r-", lw=2) plot(xs, ys2, "g-", lw=2) xlabel("$x$") ylabel("$y$") title("Trigonometric functions: $\\sin$ and $\\cos$") grid(True) legend(("$\\sin(x)$", "$\\cos(x)$")) show()
A simple XY plot (object-oriented approach)
Code:
import math import matplotlib.pyplot import numpy xs = numpy.arange(-math.pi, math.pi, 0.1) ys1 = numpy.sin(xs) ys2 = numpy.cos(xs) figure = matplotlib.pyplot.figure(figsize=(8.0, 5.0)) # The size of the figure is specified as (width, height) in inches axes = figure.add_axes([0.1, 0.25, 0.8, 0.65]) # [left, bottom, width, height], all the quantities are fractions of figure # width and height axes.grid(True) plot1 = axes.plot(xs, ys1, "r-", lw=2) plot2 = axes.plot(xs, ys2, "g-", lw=2) axes.set_title("Trigonometric functions: $\\sin$ and $\\cos$") axes.set_xlabel("$x$") axes.set_ylabel("$y$") figure.legend((plot1, plot2), ("$\\sin(x)$", "$\\cos(x)$"), 'lower center') # This is a *figure* legend, so it can appear outside the axes # Or you could use an axes legend, within the axes: # axes.legend((plot1, plot2), ("$\\sin(x)$", "$\\cos(x)$"), 'lower center') matplotlib.pyplot.show()
Saving figures
In the previous example, replace
matplotlib.pyplot.show()
with
figure.savefig("foo.eps", format="eps")
to save the figure as an EPS image instead of showing it (of course, you could do both).
You could also save it as a transparent PNG (among other things):
figure.savefig("foo.png", format="png", transparent=True)
To save the image in a file with the same base file name but a different extension, you can use something like this:
import os import sys # Save the figure in a file with the same name as the script, in the same # directory, but with an appropriate file extension scriptFilePathName = os.path.abspath(sys.argv[0]) scriptDirPathName = os.path.dirname(scriptFilePathName) scriptFileBaseName = os.path.basename(scriptFilePathName) scriptFileBaseNameNoExt = os.path.splitext(scriptFileBaseName)[0] epsFileBaseName = scriptFileBaseNameNoExt + ".eps" epsFilePathName = os.path.join(scriptDirPathName, epsFileBaseName) figure.savefig(epsFilePathName, format="eps")
