EDA & Visualization
Seeing the Story in the Signal
Data without visualization is like a map without a legend. For **Walmart**, identifying a bottleneck in the global supply chain requires more than just looking at rows—it requires **Exploratory Data Analysis (EDA)**. By visualizing the relationship between distance, weather, and transit time, analysts can find the "invisible" factors that cause delays.
In this chapter, we explore the principles of visual design and master the tools of the trade: **Matplotlib** and **Seaborn**. You will learn how to turn messy distribution data into clear, compelling charts that drive executive decisions.
The Art of Data Cleaning
Before you can visualize, you must clean. At **Walmart**, real-world logistics data is filled with "noise"—missing timestamps, duplicate GPS pings, and extreme outliers. We use statistical techniques like **Z-Score filtering** to remove anomalies that would otherwise distort our supply chain maps.
Exploratory Data Analysis (EDA)
**EDA** is the process of summarizing the main characteristics of a dataset, often with visual methods. For **Walmart**, this means looking at the **Correlation** between different variables. Does a 5-degree temperature increase in the truck correlate with a 20% increase in food spoilage? EDA gives us the answer.
Data Storytelling with Visualization
A good chart should be "glanceable." At **Walmart**, managers shouldn't have to read labels to see a problem. We use **Matplotlib** and **Seaborn** to build Heatmaps and Histograms. A **Heatmap** of global warehouse capacity can instantly show where a bottleneck is forming before it causes a stock-out.
20 Essential Matplotlib Methods (Part 1)
**Matplotlib** is the grandfather of Python visualization. These 10 methods form the backbone of every chart at **Walmart** and **Netflix**. From plt.figure() to plt.savefig(), mastering these gives you full control over how data is presented to stakeholders.
20 Essential Seaborn & Matplotlib Methods (Part 2)
Part 2 covers advanced formatting and **Seaborn's** statistical visualizations. Seaborn wraps Matplotlib with beautiful defaults and built-in statistical aggregation. Methods like sns.heatmap(), sns.boxplot(), and sns.pairplot() are essential for EDA at **Visa** and **Netflix**.
Practice Questions
Question 1
In the Walmart logistics example, why do we use a 'threshold' for cleaning transit times?
Question 2
What makes a Heatmap effective for Walmart logistics managers?