how to log commits by one author in git code example

Example 1: how to see all commits in git

$ git log --pretty=format:"%h - %an, %ar : %s"
ca82a6d - Scott Chacon, 6 years ago : Change version number
085bb3b - Scott Chacon, 6 years ago : Remove unnecessary test
a11bef0 - Scott Chacon, 6 years ago : Initial commit

Example 2: git log in command line pretty view

$ git log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit

* 3396763 - (HEAD, origin/master, master) Add twitter link (4 days ago) <Mattias Geniar>
* c73bbc9 - add facebook link (6 days ago) <Mattias Geniar>
* cb555df - More random values (6 days ago) <Mattias Geniar>
*   60e7bbf - Merge pull request #1 from TSchuermans/patch-1 (7 days ago) <Mattias Geniar>
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| * 8044a8f - Typo fix (7 days ago) <Tom Schuermans>
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