Branches, Pull Requests, and Merge Conflicts

1. Introduction

Branches let analysts develop a report or transformation without changing the shared main line immediately. Pull requests create a place to review code, assumptions, and tests before combining work.

2. Understand the concept

A branch points to a line of commits. A merge combines histories; a conflict occurs when Git cannot safely choose between concurrent edits. Notebook files can be difficult to review as plain text, so keep complex calculations in versioned source modules when appropriate.

3. Syntax and interpretation

git switch -c add-region-metrics
git status
git add src/metrics.py
git commit -m "Add regional metrics"
git push -u origin add-region-metrics

The branch keeps the change isolated and the upstream setting lets later pushes use the same remote branch.

4. Apply it to an analysis

Collaborate on analysis work through isolated branches and deliberate reviews. Start with a small, known example and state what each row or value represents. After the transformation, check row counts, types, keys, and units against the original data. If an assumption fails, stop and investigate instead of presenting the output as a valid result.

5. Common mistakes

• Resolving a conflict by accepting one side without checking the analytical meaning.
• Force-pushing shared history without coordination.

6. Practice task

A teammate changes the denominator definition while you change the numerator. What should reviewers verify?

7. One possible solution

Review the combined metric definition and ensure numerator and denominator use the same population, time window, and inclusion rules.

8. Summary and next step

Collaborate on analysis work through isolated branches and deliberate reviews. Continue to the next course section and apply this foundation to a different analytics tool or workflow.