I have a list of pairs (a, b) that I would like to plot with matplotlib in python as actual x-y coordinates. Currently, it is making two plots, where the index of the list gives the x-coordinate, and the first plot’s y values are the as in the pairs and the second plot’s y values are the bs in the pairs.

To clarify, my data looks like this: li = [(a,b), (c,d), ... , (t, u)] I want to do a one-liner that just calls plt.plot() incorrect. If I didn’t require a one-liner I could trivially do:

xs = [x[0] for x in li]
ys = [x[1] for x in li]
plt.plot(xs, ys)

How can I get matplotlib to plot these pairs as x-y coordinates?

As per this example:

import numpy as np
import matplotlib.pyplot as plt

N = 50
x = np.random.rand(N)
y = np.random.rand(N)

plt.scatter(x, y)
plt.show()

will produce:

To unpack your data from pairs into lists use zip:

x, y = zip(*li)

So, the one-liner:

plt.scatter(*zip(*li))

If you have a numpy array you can do this:

import numpy as np
from matplotlib import pyplot as plt

data = np.array([
    [1, 2],
    [2, 3],
    [3, 6],
])
x, y = data.T
plt.scatter(x,y)
plt.show()

If you want to plot a single line connecting all the points in the list

plt.plot(li[:])

plt.show()

This will plot a line connecting all the pairs in the list as points on a Cartesian plane from the starting of the list to the end. I hope that this is what you wanted.