#!/bin/sh

git rev-list --no-merges --author="$1" HEAD |
xargs git diff-tree --numstat {} |
awk '
/[0-9a-f]{40}/ {
    commits++
}
/[0-9]+\t[0-9]+/ {
    added += $1
    removed += $2
}
END {
    print "Commits:", commits
    print "Average added:", added/commits, "removed:", removed/commits 
}
'