[FIXED] Precision parameter in plt.spy (matplotlib, sparse matrices)

Issue

I am trying to use plt.spy(matrix) and would to like to understand what the precision parameter does here. The documentation states that any values of |Z| > precision will be plotted. But what does |Z| represent here?

Solution

|Z| means converting elements to their absolute values or taking modulus on each element.

This means plt.spy(matrix, precision = k) will plot elements from the matrix whose absolute value is greater than k.

import numpy as np 
import matplotlib.pyplot as plt 

data = np.array([[1, -1, 0, -10], [0, 0, 20, 0], [90, 0, 0, 1], [0, 0, 0, 0]])

fig, ax = plt.subplots(nrows=1, ncols=4)

ax[0].spy(data, precision=-0.5)
ax[1].spy(data, precision=5)
ax[2].spy(data, precision=10)
ax[3].spy(data, precision=80)

plt.show()

This gives:

However, I feel this needs to be explicitly mentioned in the documentation as it is confusing what |Z| means.

Answered By - medium-dimensional