display matrix values and colormap

问题

I need to display values of my matrix using matshow. However, with the code I have now I just get two matrices - one with values and other colored. How do I impose them? Thanks :)

import numpy as np
import matplotlib.pyplot as plt

fig, ax = plt.subplots()

min_val, max_val = 0, 15

for i in xrange(15):
    for j in xrange(15):
        c = intersection_matrix[i][j]
        ax.text(i+0.5, j+0.5, str(c), va='center', ha='center')

plt.matshow(intersection_matrix, cmap=plt.cm.Blues)

ax.set_xlim(min_val, max_val)
ax.set_ylim(min_val, max_val)
ax.set_xticks(np.arange(max_val))
ax.set_yticks(np.arange(max_val))
ax.grid()

Output:

回答1:

You need to use ax.matshow not plt.matshow to make sure they both appear on the same axes.

If you do that, you also don't need to set the axes limits or ticks.

import numpy as np
import matplotlib.pyplot as plt

fig, ax = plt.subplots()

min_val, max_val = 0, 15

intersection_matrix = np.random.randint(0, 10, size=(max_val, max_val))

ax.matshow(intersection_matrix, cmap=plt.cm.Blues)

for i in xrange(15):
    for j in xrange(15):
        c = intersection_matrix[j,i]
        ax.text(i, j, str(c), va='center', ha='center')

Here I have created some random data as I don't have your matrix. Note that I had to change the ordering of the index for the text label to [j,i] rather than [i][j] to align the labels correctly.

回答2:

In Jupyter notebooks this is also possible with DataFrames and Seaborn:

import numpy as np
import seaborn as sns
import pandas as pd

min_val, max_val = 0, 15
intersection_matrix = np.random.randint(0, 10, size=(max_val, max_val))
cm = sns.light_palette("blue", as_cmap=True)
x=pd.DataFrame(intersection_matrix)
x=x.style.background_gradient(cmap=cm)
display(x)

来源：https://stackoverflow.com/questions/40887753/display-matrix-values-and-colormap

标签

python

matrix

matplotlib

imshow