How to Add X and Y Labels to a Graph in Matplotlib with Python

In this article, we show how to add X and Y labels to a graph in matplotlib with Python.

So with matplotlib, the heart of it is to create a figure.

On this figure, you can populate it with all different types of data, including axes, a graph plot, a geometric shape, etc.

Most of the time, you will create axes so that you can add numerical values to the X and Y coordinates.

So matplotlib has a built-in set_xlabel() function and a set_ylabel() function which will enable us to add x and y labels to the graph axes.

This is shown in the following code below.

>>> import matplotlib.pyplot as plt >>> fig= plt.figure() >>> axes= fig.add_axes([0.1,0.1,0.8,0.8]) >>> axes.plot(x,y) >>> x=[1,2,3,4,5,6,7,8,9,10,11,12] >>> y= [x**2 for x in x] >>> y [1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144] >>> axes.set_xlabel('Time') <matplotlib.text.Text object at 0x05EAF810> >>> axes.set_ylabel('Time Squared') <matplotlib.text.Text object at 0x05EDD730> >>> fig.show()

So the first thing we have to do is import matplotlib. We do this with the line, import matplotlib.pyplot as plt

We then create a variable fig, and set it equal to, plt.figure()

This creates a figure object, which of course is initially empty, because we haven't populated it with anything.

So we have a figure object stored in the variable, fig, that is empty.

We then add axes to this figure using the add_axes() function.

This add_axes() function takes in a list of values. The values from the left to right are the left, bottom, width, and height.

They are numbers that vary from 0 to 1 and represent the percentage of the blank figure that you want to go and take.

So for this figure in our code, we have the line, axes= fig.add_axes([0.1,0.1,0.8,0.8])

This adds axes to the figure.

Next, we add an x label for the horizontal axis and we add a y label for the vertical axis.

We add an x label for the horizontal axis with the set_xlabel() function. We set the x label to "Time" in the code.

We add a y label for the vertical axis with the set_ylabel() function. We set the y label to "Time Squared" in the code.

To show this graph, we use the line, fig.show()

This works if you're using a python IDE other than jupyter notebooks. If you are using jupyter notebooks, then you would not use, plt.show(). Instead you would specify in the code right after importing matplotlib, %matplotlib inline

This line allows the figure of a graph to be shown with jupyter notebooks.

After running the following code above, we get the following grap shown in the image below.

So now you see a graph with x and y labels for the x and y axis.

And this is how to add x and y labels to a graph in matplotlib with Python.

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