Plot a matrix with different labels in each cell as a series of circles with colors that represent each label.

Matrix_labels_plot.py

# -*- coding: utf-8 -*-
"""
Plot a matrix with different labels in each cell as a series
of circles with colors that represent each label.

@author: Nicolas Guarin-Zapata
"""
from __future__ import division, print_function
import numpy as np
import matplotlib.pyplot as plt
from collections import OrderedDict


plt.style.use("seaborn-white")
fig = plt.figure()
ax = plt.subplot(111)

# Data and labels loading 
data = np.loadtxt("Vieira_data.csv", dtype=str, delimiter=";")
nrows, ncols = data.shape
colors = {'COA': "#e41a1c",
        'RAG': "#377eb8",
        'CHK': "#4daf4a",
        'VAR': "#984ea3",
        'DAT': "#ff7f00",
        'EXE': "#ffff33"}

# Plot circles    
for row in range(nrows):
    for col in range(ncols):
        cell_content = map(str.strip, data[row, col].split(','))
        hor_space = 1/(len(cell_content) + 1)
        for cont, label in enumerate(cell_content):
            ax.plot(col + (cont + 1)*hor_space, nrows - row - 0.5,
            'o', ms=40, color=colors[label], label=label)

# Plot grid
for row in range(nrows):
    for col in range(ncols):
        ax.plot([0, ncols], [row, row], color="black")
        ax.plot([col, col], [0, nrows], color="black")

# Labels
xticks = [k + 0.5 for k in range(ncols)]
xlabels = ["Section %i"%k for k in range(1, ncols + 1)]
yticks = [nrows - k - 0.5 for k in range(nrows)]
ylabels = ["Student %i"%k for k in range(1, nrows + 1)]
plt.xticks(xticks, xlabels)
plt.yticks(yticks, ylabels)
plt.tick_params(labeltop=True, labelbottom=False)

# Legend
box = ax.get_position()
ax.set_position([box.x0, box.y0, box.width * 0.8, box.height])
handles, labels = plt.gca().get_legend_handles_labels()
by_label = OrderedDict(zip(labels, handles))
plt.legend(by_label.values(), by_label.keys(), markerscale=0.4,
           loc='center left', bbox_to_anchor=(1, 0.5))

plt.xlim(0, ncols)
plt.ylim(0, nrows)
plt.savefig("Matrix_plot.png", dpi=300, bbox_inches="tight")
plt.savefig("Matrix_plot.svg", bbox_inches="tight")
plt.show()

Matrix_plot.png

Matrix_plot.svg

Vieira_data.csv

COA, RAG, EXE; CHK
VAR; COA, VAR
VAR, DAT; EXE