List bridge days for one year and country

bridge_days.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Bridge Days\n",
    "\n",
    "Bridge days are normal working days that happen to be between two non-working days, be they holidays or weekend days (Sat/Sun). So, they should normally fall on Mondays or Fridays, unless there are, e.g. two holidays during a week, like on Monday and Wednesday (very unlikely).\n",
    "\n",
    "This notebook contains some very simple code to calculate the list of bridge days for some given year and country as a simple use case for the ``holidays`` pacakge, see https://pypi.org/project/holidays/."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Experiment with the `holidays` package"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "from datetime import date\n",
    "import holidays"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "swiss_holidays = holidays.Switzerland()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "date(2018, 5, 9) in swiss_holidays"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "date(2018, 5, 10) in swiss_holidays"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Auffahrt'"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "swiss_holidays.get(date(2018, 5, 10))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{datetime.date(2018, 1, 1): 'Neujahr',\n",
       " datetime.date(2018, 3, 30): 'Karfreitag',\n",
       " datetime.date(2018, 4, 2): 'Ostermontag',\n",
       " datetime.date(2018, 5, 1): 'Maifeiertag',\n",
       " datetime.date(2018, 5, 10): 'Christi Himmelfahrt',\n",
       " datetime.date(2018, 5, 21): 'Pfingstmontag',\n",
       " datetime.date(2018, 10, 3): 'Tag der Deutschen Einheit',\n",
       " datetime.date(2018, 12, 25): 'Erster Weihnachtstag',\n",
       " datetime.date(2018, 12, 26): 'Zweiter Weihnachtstag'}"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "holidays.Germany(prov=\"BE\", years=2018)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{datetime.date(2018, 1, 1): 'Neujahr',\n",
       " datetime.date(2018, 1, 6): 'Heilige Drei Könige',\n",
       " datetime.date(2018, 3, 30): 'Karfreitag',\n",
       " datetime.date(2018, 4, 2): 'Ostermontag',\n",
       " datetime.date(2018, 5, 1): 'Maifeiertag',\n",
       " datetime.date(2018, 5, 10): 'Christi Himmelfahrt',\n",
       " datetime.date(2018, 5, 21): 'Pfingstmontag',\n",
       " datetime.date(2018, 5, 31): 'Fronleichnam',\n",
       " datetime.date(2018, 8, 15): 'Mariä Himmelfahrt',\n",
       " datetime.date(2018, 10, 3): 'Tag der Deutschen Einheit',\n",
       " datetime.date(2018, 11, 1): 'Allerheiligen',\n",
       " datetime.date(2018, 12, 25): 'Erster Weihnachtstag',\n",
       " datetime.date(2018, 12, 26): 'Zweiter Weihnachtstag'}"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "holidays.Germany(prov=\"BY\", years=2018)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "scrolled": true
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{datetime.date(2018, 1, 1): 'Neujahrestag',\n",
       " datetime.date(2018, 4, 1): 'Ostern',\n",
       " datetime.date(2018, 3, 30): 'Karfreitag',\n",
       " datetime.date(2018, 4, 2): 'Ostermontag',\n",
       " datetime.date(2018, 5, 1): 'Tag der Arbeit',\n",
       " datetime.date(2018, 5, 10): 'Auffahrt',\n",
       " datetime.date(2018, 5, 20): 'Pfingsten',\n",
       " datetime.date(2018, 5, 21): 'Pfingstmontag',\n",
       " datetime.date(2018, 8, 1): 'Nationalfeiertag',\n",
       " datetime.date(2018, 12, 25): 'Weihnachten',\n",
       " datetime.date(2018, 12, 26): 'Stephanstag'}"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "holidays.Switzerland(prov=\"BS\", years=2018)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Get all bridge days for one year"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [],
   "source": [
    "from datetime import datetime, timedelta\n",
    "from calendar import day_name"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [],
   "source": [
    "def is_working_day(holi, dt):\n",
    "    \"\"\"Is this a working day (not a holiday or Sat/Sun)?\"\"\"\n",
    "    \n",
    "    return not (dt in holi or dt.weekday() in (5, 6))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [],
   "source": [
    "def bridge_days_for_holiday(holi, dt):\n",
    "    \"\"\"Get working days before/after one given date (2 day window).\"\"\"\n",
    "    \n",
    "    dtm2, dtm1, dtp1, dtp2 = \\\n",
    "        [dt + timedelta(days=days) for days in [-2, -1, 1, 2]]\n",
    "    wd = is_working_day\n",
    "    if wd(holi, dtm1) and not wd(holi, dtm2):\n",
    "        yield dtm1\n",
    "    if wd(holi, dtp1) and not wd(holi, dtp2):\n",
    "        yield dtp1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [],
   "source": [
    "def show_bridge_days(holi):\n",
    "    \"\"\"List bridge days for an entire year.\"\"\"\n",
    "    \n",
    "    for dt, name in sorted(holi.items()):\n",
    "        weekday = day_name[dt.weekday()]\n",
    "        for bridge_day in bridge_days_for_holiday(holi, dt):\n",
    "            print('Holiday date: {} ({}) - {} -- bridge day: {}'.format(dt, weekday, name, bridge_day))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [],
   "source": [
    "berlin_holidays_2018  = holidays.Germany(prov=\"BE\", years=2018)\n",
    "bavaria_holidays_2018 = holidays.Germany(prov=\"BY\", years=2018)\n",
    "basel_holidays_2018   = holidays.Switzerland(prov=\"BS\", years=2018)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Holiday date: 2018-05-01 (Tuesday) - Maifeiertag -- bridge day: 2018-04-30\n",
      "Holiday date: 2018-05-10 (Thursday) - Christi Himmelfahrt -- bridge day: 2018-05-11\n",
      "Holiday date: 2018-12-25 (Tuesday) - Erster Weihnachtstag -- bridge day: 2018-12-24\n"
     ]
    }
   ],
   "source": [
    "show_bridge_days(berlin_holidays_2018)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Holiday date: 2018-05-01 (Tuesday) - Maifeiertag -- bridge day: 2018-04-30\n",
      "Holiday date: 2018-05-10 (Thursday) - Christi Himmelfahrt -- bridge day: 2018-05-11\n",
      "Holiday date: 2018-05-31 (Thursday) - Fronleichnam -- bridge day: 2018-06-01\n",
      "Holiday date: 2018-11-01 (Thursday) - Allerheiligen -- bridge day: 2018-11-02\n",
      "Holiday date: 2018-12-25 (Tuesday) - Erster Weihnachtstag -- bridge day: 2018-12-24\n"
     ]
    }
   ],
   "source": [
    "show_bridge_days(bavaria_holidays_2018)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Holiday date: 2018-05-01 (Tuesday) - Tag der Arbeit -- bridge day: 2018-04-30\n",
      "Holiday date: 2018-05-10 (Thursday) - Auffahrt -- bridge day: 2018-05-11\n",
      "Holiday date: 2018-12-25 (Tuesday) - Weihnachten -- bridge day: 2018-12-24\n"
     ]
    }
   ],
   "source": [
    "show_bridge_days(basel_holidays_2018)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Challenge: Draw a world map of #holidays and #bridge days / year\n",
    "\n",
    "More to come… But notice, that the ``holidays`` package does not provide holidays for all countries!"
   ]
  }
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