Search code examples
pythonpyqtgraph

Does PyQtGraph have an option for placing symbols on only some fraction of points, similar to Matplotlib's markevery keyword?

The following code snippet and plot shows how Matplotlib's markevery keyword can be convenient for placing markers on line without cluttering the plot by marking every point in a large dataset. Is there a similar feature in PyQtGraph, or do I just have to call plot twice to put symbols on a subset of the data?

from matplotlib import pyplot as plt
import pyqtgraph as pg
import numpy as np

x = np.linspace(0, 10, 151)
y = x**2

pg.plot(x, y, symbol='o')

plt.plot(x, y, marker='o')
plt.plot(x, y+10, marker='o', markevery=10)
plt.show()

enter image description here

Solution

  • If this keyword does not exist in pyqtgraph, you could simply use the following code instead:

    pg.plot([j for i, j in enumerate(x) if i%10==0], [j for i, j in enumerate(y) if i%10==0], symbol='o')

    where you could replace i%10==0 with i%z==0, where z is equivalent to the markevery integer.

    --or--

    def pg_markevery(arr, markevery):
    return [j for i, j in enumerate(arr) if i%markevery==0]

pg.plot(pg_markevery(x, markevery=10), pg_markevery(y, markevery=10), symbol='o')