Creating Custom Bar Charts with Python Matplotlib

The article explains how to quickly draw bar charts that meet specific requirements using Python.

Loading libraries

import matplotlib.pyplot as plt import matplotlib.font_manager as mfm from matplotlib import style style.use('ggplot') # load ggplot style font_path = "/System/Library/Fonts/STHeiti Light.ttc" # local Chinese font prop = mfm.FontProperties(fname=font_path)

Single bar chart

Data is defined as a list total = [3, 5, 6, 7, 8, 6, 4, 3, 3, 22, 4, 8, 7, 13, 7, 7, 15, 10, 6, 52, 8, 2, 3, 26, 1, 1, 0, 2, 0, 3] . The basic plot is created with:

plt.bar(range(len(total)), total) plt.title('单一柱图', fontproperties=prop) plt.savefig("单一柱图.png", dpi=700, fontproperties=prop) plt.show()

The initial result shows incorrect axis scaling and missing last bar, so the article improves the chart by customizing the x‑axis.

Custom x‑axis labels

Labels are generated for intervals of 10, showing only every 50th label and the first interval as "0~10":

x_labels = [] for item in range(0, 300, 10): x = item + 10 if x == 10: x_labels.append("{}~{}".format(0, 10)) elif x % 50 == 0: x_labels.append(str(x)) else: x_labels.append(None) x = range(len(total)) plt.bar(x, total) plt.title('单一柱图', fontproperties=prop) plt.xticks(x, x_labels) plt.savefig("单一柱图.png", dpi=700, fontproperties=prop) plt.show()

Font size and rotation can be further adjusted:

plt.xticks(x, x_labels, rotation=30, fontsize=5)

Multi‑bar chart

Data for three groups is stored in a 2‑D list:

A = [[28, 3, 5, 6, 3, 7, 2, 4, 9, 95], [58, 6, 13, 13, 5, 12, 17, 11, 10, 102], [60, 22, 21, 41, 11, 5, 1, 2, 3, 4]]

Horizontal positions and labels are generated similarly, then three bars are plotted side by side with different colors and a legend:

# generate x‑axis labels x_labels = [] for item in range(0, 100, 10): x = item + 10 if x == 10: x_labels.append("{}~{}".format(0, 10)) else: x_labels.append(str(x)) x = np.arange(10) plt.bar(x + 0.00, A[0], color='orange', width=0.3, label='A') plt.bar(x + 0.30, A[1], color='royalblue', width=0.3, label='B') plt.bar(x + 0.60, A[2], color='brown', width=0.3, label='C') plt.title('多柱图', fontproperties=prop) plt.xticks(x + 0.30, x_labels) plt.legend(loc='best') plt.savefig('多柱图.png', dpi=700, fontproperties=prop) plt.show()

The article concludes with the resulting charts and encourages readers to explore further Python learning resources.