from __future__ import division, print_function # Always do this just to
                                                # ensure compatability
                                                # between python 2.7 and 3
import matplotlib.pylab as P

# Always do these next to lines to enable LaTeX to be used on the
# matplotlib plots
P.rc('text', usetex=True)
P.rc('font', family='serif')

x = P.linspace(0, 2, 15) # x is an array going from 0 to 2 evenly divided
                         # into 15 points


y_1 = x
theta_i = x**2
y_3_hat = P.sqrt(x)

P.plot(x, y_1, linewidth=2, color='red',
    label=r"$y_1$") # note that the `r` means "raw", and is needed if
                    # you're using latex. Else, it's unnecessary.

P.plot(x, theta_i, linewidth=2, color='blue',
    label=r"$\theta_{i}$")

P.scatter(x, y_3_hat, linewidth=2, color='green',
    label=r"$\widehat{y}_3$") # I prefer `widehat` to `hat` xP

P.title("This is a test plot of 3 functions")
P.xlabel(r"$x$-axis")
P.ylabel("What even are these units?")
P.legend() # Enables the legend that shows the labels you gave to each plot


# Save the plot if you want
P.savefig("example.eps") # eps is the best format for LaTeX. It's a vector
                         # format, like SVG, so no quality gets lost. PNG
                         # and other formats work as well

# Clear the plot if you want
# P.clf()

# Show the plot if you want (note that this stops execution until you close
# the plot)
P.show()