First of all, here's the root of the documentation: https://matplotlib.org/

The Gallery shows how flexible this graphics library is.

To install it into Thonny:

1. First check to see if it's already installed.  In the shell, type "import matplotlib"
2. If not installed, go to menu: Tools/Manage packages, type "matplotlib" in the text box, click on "Find package...", and then click on Install
3. Then try Step #1

For the code below, import it using:

import matplotlib.pyplot as plt

"plt" is an abbreviation for "matplotlib.pyplot" to save us from finger fatigue.

Here are the basic plotting functions:


plt.plot(y_data) or plt.plot(x_data,y_data)

y_data is a list of values that will be plotted (graphed) on the y-axis
x_data, if included, will be the corresponding x-values

plt.plot([1,4,9,16,25])

plt.plot([1,2,3,4],[1,4,9,16]) will plot the points: (1,1), (2,4), (3,9) and (4,16)

plt.plot(x_data,y_data,label=some-string-identifying-thisdata)

plt.show()

Actually display the plot (do this as the last step in building up a plot)

plt.title(some_title)

Registers the title that will be shown for the plot

plt.ylabel(a_label), plt.xlabel(another_label)

creates labels for the axes

plt.axis([xmax, xmin, ymax, ymin])

sets the limits for the axes

plt.legend(some_text)

display a legend (colored labels) for the graph

plt.scatter(x_data, y_data, scale)

creates a scatter plot, scale sets the size of the dots

		
import matplotlib.pyplot as plt
import random

# Simple plot of squares
def one():
    data = []
    for i in range(100):
        data.append(i*i)
    plt.plot(data)
    plt.show()
    
# Scatter plot of squares
def two():
    data = []
    for i in range(100):
        data.append(i*i)
    plt.scatter(list(range(100)),data,1)
    plt.show()

# Scatter (or normal graph) with random noise added
def three():
    data = []
    for i in range(100):
        y = i*i
        y += random.random()*y/10
        data.append(y)
    plt.scatter(list(range(100)),data,10)
    #plt.plot(data)
    plt.legend('Squares')
    plt.axis([0,100,0,10000])
    plt.show()
    
# Two graphs in the same display
def four():
    data_1 = []
    data_2 = []
    for i in range(10):
        data_1.append(i*i)
        data_2.append(i*i*i)
    x_data = list(range(10))
    plt.plot(x_data,data_1,label='squares')
    plt.plot(x_data,data_2,label='cubes')
    plt.title('Simple')
    plt.legend()  # display the labels
    plt.show()