📊 Day 24: Calendar Heatmap in Python

 

📊 Day 24: Calendar Heatmap in Python

🔹 What is a Calendar Heatmap?

A Calendar Heatmap visualizes data values day-by-day across a calendar using color intensity.
Each cell represents a date, and the color shows the magnitude of activity on that day.

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🔹 When Should You Use It?

Use a calendar heatmap when:

• Analyzing daily patterns

• Tracking habits or activity streaks

• Visualizing time-series seasonality

• Showing long-term daily trends

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🔹 Example Scenario

Suppose you want to analyze:

• Daily website visits

• GitHub contributions

• Sales per day

• Workout or study streaks

A calendar heatmap helps you instantly see:

• Busy vs quiet days

• Weekly patterns

• Seasonal behavior

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🔹 Key Idea Behind It

👉 Each square = one day
👉 Color intensity = activity level
👉 Patterns emerge over weeks & months

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🔹 Python Code (Calendar Heatmap)

import pandas as pd

import numpy as np

import seaborn as sns

import matplotlib.pyplot as plt

dates = pd.date_range("2023-01-01", "2023-12-31")

values = np.random.randint(1, 10, len(dates))

df = pd.DataFrame({

    "date": dates,

    "value": values

})

df["week"] = df["date"].dt.isocalendar().week.astype(int)

df["weekday"] = df["date"].dt.weekday

calendar_data = df.pivot_table(

    index="week",

    columns="weekday",

    values="value",

    aggfunc="sum"

)

plt.figure(figsize=(12, 6))

sns.heatmap(calendar_data, cmap="YlGnBu")

plt.title("Calendar Heatmap")

plt.xlabel("Day of Week (0=Mon)")

plt.ylabel("Week of Year")

plt.show()

🔹 Output Explanation

• Each cell shows activity for a day

• Darker colors mean higher values

• Horizontal patterns show weekly trends

• Easy to spot streaks and gaps

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🔹 Calendar Heatmap vs Regular Heatmap

Feature	Calendar Heatmap	Regular Heatmap
Time-based	Yes	No
Layout	Calendar-like	Matrix
Use case	Daily trends	Correlations
Storytelling	High	Medium

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🔹 Key Takeaways

• Calendar heatmaps reveal daily behavior patterns

• Ideal for habit tracking & time analysis

• Excellent for long-term datasets

• Very popular in analytics & dashboards