Correlation Heatmaps & PairPlots for Multivariate EDA0%
Correlation Heatmaps & PairPlots for Multivariate EDA
Beginner12 min read•Updated: Jul 11, 2026
Correlation Heatmaps & PairPlots for Multivariate EDA
Reading Time: 8 Mins | Level: Intermediate
1. Multivariate Exploration
When exploring a dataset with multiple numeric columns, you must answer two core questions:
- 1Which features are strongly correlated with each other?
- 2Are there collinear features that could distort machine learning models?
2. Correlation Heatmaps (sns.heatmap)
The Pearson correlation coefficient $r$ ranges from -1.0 (perfect negative correlation) to +1.0 (perfect positive correlation), with 0.0 representing no linear relationship.
Python
import seaborn as sns
import matplotlib.pyplot as plt
df = sns.load_dataset('iris')
# Compute correlation matrix of numeric columns
corr_matrix = df.drop('species', axis=1).corr()
fig, ax = plt.subplots(figsize=(7, 5))
sns.heatmap(
corr_matrix,
annot=True, # Print correlation numbers inside cells
fmt='.2f', # Format numbers to 2 decimal places
cmap='coolwarm', # Diverging color map
vmin=-1, vmax=1, # Anchors color map between -1 and +1
linewidths=1.5,
cbar=True,
ax=ax
)
ax.set_title('Feature Correlation Heatmap Matrix')
plt.show()
3. PairPlots for Pairwise Feature Inspection
Python
# PairPlot plots bivariate distributions across all pairs of numeric columns
sns.pairplot(df, hue='species', palette='Dark2', diag_kind='kde')
plt.show()
Interactive Quiz
Multiple Choice Questions
Question 1
What does a Pearson correlation coefficient value of $r = -0.92$ indicate?
Question 2
In
sns.heatmap(), which parameter prints the numerical correlation coefficients directly inside each grid cell?Question 3
What does
sns.pairplot() render?Question 4
Why should you pass
vmin=-1, vmax=1 when plotting a correlation matrix heatmap?Question 5
What type of plot is typically drawn along the diagonal of a
pairplot when using diag_kind='kde'?Next Lesson
Measures of Central Tendency & Dispersion (Mean, Median, Std, IQR)
Continue learning with hands-on practice, examples, and exercises in the upcoming topic.
Related Lessons
Practice Quiz
Test your understanding of this lesson with 5 questions. Each question has one correct answer.