Question

In this example of a marker from my scatter plot, I have set the color to green, and edge color to black, and hatch to "|". For the hatch pattern to show up at all, I must set the edgecolor; however when I do, I get a very thick border around the marker. Two questions:

1. How can I to set the size of this border (preferably to 0)?

2. How can I increase the thickness of the hatch lines?

Answer 1

1. You just need to set the linewidth to control the marker border thickness.
2. You can increase the density of hatching, by repeating symbols (in the example below, the '|' is repeated in the R/H pane; note that to obtain NW->SE diagonal lines the symbol must be escaped so needs twice as many characters to really double it — '\\\\' is density 2 while '||||' is density 4). However, I don’t think the thickness of individual lines within hatching is controllable.

See the code example below to produce scatter plots such as these:

import matplotlib.pyplot as plt
# generate some data
x = [1,2,3,4,5,8]
y= [i**2 for i in x]
y2= [60-i**2+3*i for i in x]

# plot markers with thick borders
plt.subplot(121)
plt.scatter(x,y, s=500, marker='s', edgecolor='black', linewidth=3, facecolor='green', hatch='|')
# compare with no borders, and denser hatch.
plt.subplot(122)
plt.scatter(x,y2, s=500, marker='s', edgecolor='black', linewidth=0, facecolor='green', hatch='||||')

plt.show()

matplotlib documentation on collections
and scatter.