Heat map
A heat map is a grid of colored cells where the shade shows the size of each value, like sales by day and hour, so you can see at a glance where activity bunches up.
Select any words here to ask your Maestro about them.
Failed payments peak on Friday evening, the busiest slot of the week. You shade each cell by failure rate (failed ÷ orders) instead. Where does Friday evening's rate rank?
Where you see it: sales by day and hour, clicks across a web page, correlations between many columns. It trades exact numbers for a quick read of where activity bunches up.
How it's made: in Excel, with a pivot table and conditional formatting; in Python or Power BI, with a ready-made chart type.
Where it breaks: when one outlier takes over the whole scale, or when the color looks more precise than it is. Keep the numbers close by.
How it's used
One in Excel
A heat map in Excel
- Make a pivot table: time slots in Rows, days in Columns, orders in Values
- Select the numbers inside the table
- marked: Home > Conditional Formatting > Color ScalesPick a two-color scale that runs from white to one color: it reads better than a rainbow.
- Check the palest and darkest cells against their numbers
When to look closer
Rows in alphabetical order
Time slots A to Z
- marked: Afternoon, Evening, Midday, Morning
Your tool sorts the time slots A to Z. What happens to the day's rhythm in the heat map?
Ask your Maestro about Heat map
It answers from the free course page closest to this word, the way it answers while you study.
You: What does "Heat map" mean, in plain words?
Your Maestro: I'll explain it with a case of yours: it sticks better than a definition. Which two things at work would you like to cross in a grid?
Asking about: Answers from the page "How do I count the missing values in each column with pandas?"
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Related terms
- Conditional formatting
Conditional formatting changes a cell's color or style based on its value, with rules like "greater than", "duplicates" or a color scale, and updates on its own when the data changes.
- Pivot table
A pivot table summarizes a long table in seconds: it groups by the columns you pick and sums, counts or averages another, with no formulas.
- Correlation
Correlation measures how closely two numbers move together, from −1 to 1. Near 1: when one rises, so does the other. Near 0: no straight-line link.
- Outlier
An outlier is a value that sits far from the rest, like a $9,800 order among $300 ones. It can be a data-entry error or a real, important case: before you drop it, find out which.