Bar Charts
Compare values across discrete categories
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Explanation
Bar charts compare values across discrete categories.
fig, ax = plt.subplots()
categories = ['Math', 'Science', 'English', 'Art']
scores = [85, 92, 78, 88]ax.bar(categories, scores, color='steelblue', edgecolor='black') ax.set_title('Average Scores by Subject') ax.set_ylabel('Score') plt.show() ```
Horizontal bars (better for long category names): ``python ax.barh(categories, scores)
Grouped bars:
python import numpy as np x = np.arange(len(categories)) width = 0.35 ax.bar(x - width/2, scores_2022, width, label='2022') ax.bar(x + width/2, scores_2023, width, label='2023') ax.set_xticks(x) ax.set_xticklabels(categories) ax.legend()
pandas shortcut:
python df.groupby('dept')['salary'].mean().plot(kind='bar')
Examples
Horizontal bar chart with pandas
barh() is easier to read when category names are long
import pandas as pd
import matplotlib.pyplot as plt
df = pd.DataFrame({'language':['Python','JavaScript','Java','C++','Go'],'popularity':[30,25,15,10,8]})
fig, ax = plt.subplots(figsize=(7,4))
ax.barh(df['language'], df['popularity'], color='coral')
ax.set_xlabel('Popularity Index')
ax.set_title('Programming Language Popularity')
plt.tight_layout()
plt.show()Next in Data Visualization
Histograms