Why Do People Use Git?

📝 Recording

take logs of all coding activity of you and your collaborators

🕒 Restorable

go back to a previous version of codes

🔍 Comparable

focus on the change in the codes, and detect bugs

🔀 Branch

separate things complete and things under development

Is Git Easy?

No. I am sorry.

• Git has many commands with many options
• Need some knowledge to recover from a trouble
• Git allows various styles to use, which are different across people and organization

I propose

• First follow my workflow, which requires the minimum knowledge
• Once you’re comfortable with it, learn the detail

CUI vs GUI?

GUI Applications for Git & GitHub

• GitHub Desktop
• VSCode
• Fork

I propose

• Hybrid way in VSCode
• CUI knowledge is necessary for GUI

Local & Remote Repository

Commit Is a Save Point!

You Can Go Back to Any Commit

You Can Compare Any Two Commits

HEAD and Branch

• Branch: a label of commit
• HEAD: the branch you are seeing

Merge

1. Sync Local Repository

git checkout main
git pull origin main

2. Write Your Codes

After checkout to new developing branch

git checkout -b "dev"

Write your codes

3. Commit

At a good saving point

git add foo1.txt foo2.txt
git commit -m "hogehoge"

If you want to stage all modified files, git add .

4. Push to the Remote Repository

git push origin dev

5. Pull Request and Merge

Questions about Branches

Why Do We Use Branch?

• Keep "main" branch clean
• Easy to detect a bug (because "main" works perfectly)

When Should I Create a Branch?

A simple suggestion is "feature branch workflow"

• Create a branch if you want to add a new feature
• For the economic research, model, slides, paper, and a BUG-FIX
• Delete branch when it’s done
  • In remote repository, after the merge, the button appears
  • In local repository, run git branch -d BRANCH_NAME

Data Version Control (DVC)

How Can We Work with Data in Git?

• We want to store the data in the Git project (because referred in the code)
• Not interested in change in each line of the data (imagine data cleaning)
• There is a limit for the file size in GitHub (100 MB)

How Does DVC Work?

• Create a text file for the meta-information of the data
• Git manages only the text file
• Git can follow when the data is added, modified, deleted through the text file
• The original data is stored in the remote storage (Google Drive, Amazon S3, …)

How Does DVC Work?

DVC Commands

1. Before your commit, create DVC files

dvc add foo1.csv

You can specify a folder with -R option dvc add -R data

2. After Git push, push data to the remote storage

dvc push

3. After Git pull, pull data from the remote storage

dvc pull

Troubleshoot

Git Reference log

You can see all the git command activity

git reflog

Git Reset

You can reset any git activity

git reset --soft COMMIT_ID_OR_REFLOG_ID

Conflict

Conflict might occur

• When merge
• If the main and development branches have different lines of codes in the same file

To solve this

• You can open a text editor
• Choose which lines you keep