NumPy : Beginner's Guide - Third Edition

Time for action – plotting a polynomial function

To illustrate how plotting works, let's display some polynomial graphs. We will use the NumPy polynomial function poly1d() to create a polynomial.

1. Take the standard input values as polynomial coefficients. Use the NumPy poly1d() function to create a polynomial:

   func = np.poly1d(np.array([1, 2, 3, 4]).astype(float))

2. Create the x values with the NumPy the linspace() function. Use the range -10 to 10 and create 30 even spaced values:

   x = np.linspace(-10, 10, 30)

3. Calculate the polynomial values using the polynomial we created in the first step:

   y = func(x)

4. Call the plot() function; this does not immediately display the graph:

   plt.plot(x, y)

5. Add a label to the x axis with the xlabel() function:

   plt.xlabel('x') ...