Tuesday, April 26, 2011

How to plot a function using matplotlib

We will see how to evaluate a function using numpy and how to plot the result.
import pylab
import numpy

x = numpy.linspace(-15,15,100) # 100 linearly spaced numbers
y = numpy.sin(x)/x # computing the values of sin(x)/x

# compose plot
pylab.plot(x,y) # sin(x)/x
pylab.plot(x,y,'co') # same function with cyan dots
pylab.plot(x,2*y,x,3*y) # 2*sin(x)/x and 3*sin(x)/x
pylab.show() # show the plot
The command pylab.show() will open a window with the following plot:

8 comments:

  1. Very good info, thanks!!!

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  2. How to realize it without numpy?!

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    Replies
    1. It's easy, you just need to generate the vectors x and y in another way. For example, x = [a*1.0 for a in range(0,10)] and y = [sin(xx) for xx in x].

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  3. Is it possible to plot a function and not just an equation?

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