🔥 Seaborn Heatmap
Last Updated: 07 Nov 2025
A heatmap visualizes data in a matrix form where values are represented using colors. Most commonly used for:
- Correlation matrix
- Pivot tables
Hinglish Tip 🗣: Heatmap me color hi value hota hai — darker/lighter color = high/low value.
Syntax
sns.heatmap(data)
plt.show()
📘 Example Dataset
df = sns.load_dataset('tips')
We will create a correlation matrix first:
corr = df.corr(numeric_only=True)
🔥 Basic Heatmap
sns.heatmap(corr)
plt.show()
Important Parameters
- annot Shows values on heatmap.
sns.heatmap(corr, annot=True)
plt.show()
- fmt Format of annotation numbers.
sns.heatmap(corr, annot=True, fmt='.2f')
- cmap Color palette. Popular options: magma, viridis, crest, rocket
sns.heatmap(corr, cmap='coolwarm')
- linewidths Lines between cells.
sns.heatmap(corr, linewidths=1)
- linecolor Color of grid lines.
sns.heatmap(corr, linewidths=1, linecolor='white')
- square Make cells perfect squares.
sns.heatmap(corr, square=True)
- cbar Show/hide color bar.
sns.heatmap(corr, cbar=False)
- cbar_kws Customize color bar.
sns.heatmap(corr, cbar_kws={'shrink':0.5})
- mask Hide specific parts of heatmap. Example: show only upper triangle.
import numpy as np
mask = np.triu(np.ones_like(corr))
sns.heatmap(corr, mask=mask)
⭐ Full Example
sns.heatmap(
corr,
annot=True,
fmt='.2f',
cmap='viridis',
linewidths=0.8,
linecolor='white',
square=True,
cbar_kws={'shrink': 0.6}
)
plt.show()
Quick Practice
- Load penguins dataset.
- Compute correlation matrix.
- Plot heatmap with annot=True.
- Change colormap.
- Show only upper triangle using mask.
