Matplotlib snippet for visualising matrices nicely.

grid_show.py

import matplotlib.pyplot as plt
import seaborn as sns


sns.set(context='paper', style='whitegrid')


def grid_show(grid, horizontal_labels, vertical_labels=None, cmap='binary', grid_color='#efefef'):
    ax = plt.gca()
    image = ax.imshow(grid, 
          interpolation=None,
          extent=(-0.5, grid.shape[1] - 0.5,
                  -0.5, grid.shape[0] - 0.5),
          cmap=cmap)
          
    tick_marks = np.arange(len(grid))
    plt.grid(True)
    plt.yticks(tick_marks, horizontal_labels[::-1])
    plt.xticks(tick_marks, vertical_labels, rotation=90)
    if vertical_labels is None:
        ax.set_xticklabels([])
    plt.setp(ax.spines.values(), linewidth=2)
    ax.set_xticks(np.arange(-.5, grid.shape[1] + .5, 1), minor=True)
    ax.set_yticks(np.arange(-.5, grid.shape[0] + .5, 1), minor=True)
    ax.grid(which='minor', color=grid_color, linestyle='-', linewidth=str(1))
    ax.grid(False, which='major')
    ax.set(frame_on=True)
    ax.tick_params(axis='both', which='both', length=0)