script to extra git authors (per year)

authors-over-time.pl

#!/usr/bin/perl
my @a = `git log --use-mailmap --reverse --pretty=fuller --no-color --date=short --decorate=full  | egrep "^(Author|CommitDate):"`;

my $c=1;
my $year=1999;
for(@a) {
    chomp;
    my $line = $_;
    if(/^CommitDate: (.*)/) {
        if($1 =~ /^(\d\d\d\d)/) {
            $year = $1;
        }
    }
    if(/^Author: *([^\<]*) \</) {
        my ($auth)=($1);
        $uniq{$auth}++;
        $uniqyear{$auth.$year}++;
        $total{$auth}++;
        if($uniq{$auth} == 1) {
            # this many did their first commit this year
            $when{$year}++;
        }
        if($uniqyear{$auth.$year} == 1) {
            # total count of authors this year
            $whenyear{$year}++;
        }
        #printf "$c;%d\n", scalar(keys %uniq) if(!($c % 50));
        $c++;
    }
}

# iterate over all authors, count those who did less than three that year
for my $a (sort keys %total) {
    for my $y (sort keys %when) {
        #print STDERR "check $a for $y\n";
        if($uniqyear{$a.$y} && ($uniqyear{$a.$y} < 3)) {
            $driveby{$y}++;
        }
        if($uniqyear{$a.$y} && ($uniqyear{$a.$y} > 9)) {
            $tenmore{$y}++;
        }
    }
}

print "Year;First Commit;Unique Authors;Less than 3 commits;3 commits or more;10 commits or more\n";
for my $y(2000 .. 2019) {
    printf("%d;%d;%d;%d;%u;%u\n", $y, $when{$y}, $whenyear{$y}, $driveby{$y},
           $whenyear{$y} - $driveby{$y},
           $tenmore{$y});
}