Produces a heatmap of commit activity from Unix timestamps.

git-commit-heatmap.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# A Python 3.5+ script that prints a coloured heatmap of activity similar to
# the one shown in one's GitHub profile. It has some limitations such as not
# printing month and weekday names, because it is hard to predict where to put
# the month name. It should work in any terminal that supports 256 colors [1].
#
# The script accepts a list of Unix timestamps as piped or redirected
# input. For instance, to visualize the commit heatmap of a locally cloned
# repository, use the command below. Suggested additional flags to git-log(1)
# are --author/--committer, --since/--until, --no-merges etc.
#
#   $ git -C /path/to/repo log --format="%at" | python git-commit-history.py
#
# If one has $HISTTIMEFORMAT set, then the Bash history file can also be parsed
# to extract timestamps, for example as done below.
#
#  $ awk -F# '/^#[0-9]{10}/ {print $2}' $HISTFILE \
#    | python git-commit-heatmap.py
#
# [1] https://gist.github.com/XVilka/8346728

from datetime import date, timedelta
from fileinput import input as finput
from math import log

try:
    dates = sorted(date.fromtimestamp(int(line)) for line in finput())
    first, last = dates[0], dates[-1]
except:
    raise SystemExit("Empty or incorrect input!")

data = {last - timedelta(days=x): 0 for x in range((last - first).days + 1)}
for day in dates:
    data[day] += 1

weekdays = {(i - 1) % 7: [] for i in range(7)}
for day in data.keys():
    weekdays[day.weekday()].append(day)

# ansi escape codes to set background to several shades of green
# range(236, 255, 2) gives a nice grayscale option
colors = [
    "\x1b[48;5;{}m  \x1b[0m".format(color)
    for color in [8, 51, 86, 121, 156, 191, 226, 220, 214, 208, 202]
]

first_wk_day = first.weekday()
indent = 0 if first_wk_day != 6 else 7
for wkday, days in weekdays.items():
    if indent <= first_wk_day:
        print("  ", end="")
        indent += 1
    for day in sorted(days):
        heat = min(int(log(data[day], 2) if data[day] else -1) + 1, 10)
        print(colors[heat], end="")
    print()