Relationships: scatter and line
Plotting two variables together.
Relationships: scatter and line is a free Data Science Academy lesson on CoddyKit — lesson 3 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Data Science Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
From One Column to Two
Distributions look at a single column. Now you ask how two columns move together, which is the heart of finding a relationship.
The Scatter Plot
A scatter plot places one dot per row, using two columns as x and y. The cloud of dots reveals how the variables connect.
sns.scatterplot(data=df, x="hours", y="score")Read the Pattern
Dots sloping up mean a positive link, sloping down means negative, and a shapeless blob means little correlation between them.
Add a Third Dimension With hue
Color the dots by a category using hue. Now one plot shows the relationship split across each group at the same time.
sns.scatterplot(data=df, x="hours", y="score", hue="grade")Size Encodes a Fourth Variable
Map a column to dot size to pack in even more. Bigger dots can mean larger sales, population, or any numeric measure.
sns.scatterplot(data=df, x="hours", y="score", size="effort")The Line Plot
When x is ordered, like dates or steps, a line plot connects the points to show how a value changes over that sequence.
sns.lineplot(data=df, x="month", y="revenue")Scatter vs Line
Use a scatter for unordered pairs and a line when the x axis flows in order. Picking the right one keeps the trend honest.
Lines Aggregate Automatically
If several rows share an x value, seaborn averages their y and draws a shaded confidence band around the line for you.
Multiple Lines With hue
Add hue to a line plot and each category becomes its own colored line. Comparing trends across groups takes just one extra word.
sns.lineplot(data=df, x="month", y="revenue", hue="region")Add a Trend Line With regplot
Want the best-fit line drawn through a scatter? regplot overlays a regression line so the direction is impossible to miss.
sns.regplot(data=df, x="hours", y="score")Correlation Is Not Causation
A clear upward cloud shows two things rise together, not that one causes the other. Always pair a plot with judgment.
Quick Check
Your x axis is ordered by month and you want to show change over time.
Recap: Show How Two Things Connect
You can now reveal relationships with scatter for pairs and lines for ordered trends, and add hue or size to layer in more. 🔗
Frequently asked questions
Is the “Relationships: scatter and line” lesson free?
Yes — the full text of “Relationships: scatter and line” is free to read here on the web, and the Data Science Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Data Science Academy course, upgrade to CoddyKit PRO.
What will I learn in “Relationships: scatter and line”?
Plotting two variables together. You practise Data Science Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Data Science Academy?
No prior experience is required. Data Science Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Relationships: scatter and line” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Data Science Academy lesson?
Yes. Every Data Science Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Why seaborn Over Raw matplotlib
- Distributions: hist, kde, box
- Relationships: scatter and line
- Facets, Hue, and Style