This graph is starting to get interesting! It’s pretty hard to interpret, though, so let’s add a title and legend.

When we set the parameters for our line chart and changed line formatting, we did all of that inside the .plot() function. (Remember, .plot() is a graph function in matplotlib because it makes a line graph.)

To make the title and legend, we’re going to use two of matplotlib’s general functions.

To put a title on any graph, we simply type the title as a string into plt.title(). For example, plt.title(‘Effect of Hunger on Mood’) could go on a scatterplot showing a correlation between hunger level and mood. By default, the title is positioned at the top of the figure.

To make a legend, we use the general function plt.legend(). We use this general function to set up the legend, but in order to tell the legend function which line is which, we’ll also put a label argument inside each line function. .legend() uses .plot()’s label parameter as its information source.

plt.plot(x, y, color='red', label='Line Y')
plt.plot(x, z, color='green', label='Line Z')
plt.legend()

This code will produce a graph with a legend that identifies the red line as Line Y and the green line as Line Z.

To position the legend, we can use the plt.legend() parameter bbox_to_anchor, which takes an (x,y) coordinate pair as its argument. For the x-coordinate, 0 is the left edge of the graph and 1 is the right edge. For the y-coordinate, 0 is the bottom edge of the graph and 1 is the top. For example, plt.legend(bbox_to_anchor = (1, 0.5)) places the legend to the right of the figure (all the way at 1 on the x-coordinate), in the middle of the vertical space (0.5 on the y-coordinate).

plt.plot(x, y, color='red', label='Line Y')
plt.plot(x, z, color='green', label='Line Z')
plt.legend(bbox_to_anchor = (1, 0.5))

This code will make the same graph as above, with the legend positioned to the right of the graph.