gestats.py

import calendar
import csv
import datetime
import dateutil.parser
import json
from dateutil.relativedelta import *
from dateutil.rrule import rrule, MONTHLY, YEARLY
from urllib import request
from urllib.parse import urlencode

base_url = "https://www.performance.service.gov.uk/data/register-to-vote/volumetrics"

important_dates = {
    "GE2015": datetime.datetime(2015,5,7),
    "EURef2016": datetime.datetime(2016,6,23),
    "GE2017": datetime.datetime(2017,6,8),
    "GE2019": datetime.datetime(2019,12,12)
}
months_back = 6

age_groups = [
    "18-24",
    "25-34"
]
metrics = {}

f = open("./metrics.csv", "w")
writer = csv.writer(f)

headers = ["Event"] + [x for x in range(months_back)]
months_back -= 1

for event, event_date in important_dates.items():

    headers.append(event)

    (_, last) = calendar.monthrange(event_date.year, event_date.month)

    
    start_date = event_date - relativedelta(months=months_back)
    start_date = start_date.replace(day=1)

    end_date = datetime.datetime(event_date.year, event_date.month, last)

    index = 0

    for date in rrule(MONTHLY, dtstart=start_date, until=end_date):

        index += 1

        (_, last) = calendar.monthrange(date.year, date.month)

        start_at = datetime.datetime(date.year, date.month, 1).astimezone(datetime.timezone.utc)
        end_at = datetime.datetime(date.year, date.month, last, 23, 59, 59).astimezone(datetime.timezone.utc)

        qs = urlencode({
            'period': 'month',
            'filter_by': 'metricName:age_band',
            'collect': 'count:sum',
            'group_by': 'value',
            'start_at': start_at.isoformat(),
            'end_at': end_at.isoformat(),
            'format': 'json',
        })

        url = f'{base_url}?{qs}'
        print(f'Making request to {url}')

        req =  request.Request(base_url + '?' + qs)
        resp = request.urlopen(req)

        payload = json.load(resp)
        data = payload["data"]

        metrics[event] = metrics.get(event) or {}

        for segment in data:

            if segment.get('value') in age_groups:

                year_stats = metrics[event]

                year_stats[index] = year_stats.get(index) or 0
                year_stats[index] += segment.get('count:sum')

writer.writerow(headers)

for event, value in metrics.items():

    values = list(value.values())

    row = [event] + values
    writer.writerow(row)

yearlystats.py

import calendar
import csv
import datetime
import dateutil.parser
import json
from dateutil.rrule import rrule, MONTHLY, YEARLY
from urllib import request
from urllib.parse import urlencode

base_url = "https://www.performance.service.gov.uk/data/register-to-vote/volumetrics"

start_date = datetime.datetime(2015,1,1)
end_date = datetime.datetime(2019,12,31)

age_groups = [
    "18-24",
    "25-34"
]
metrics = {}

f = open("./metrics.csv", "w")
writer = csv.writer(f)

headers = ["Year"]

for date in rrule(MONTHLY, dtstart=start_date, until=end_date):

    headers.append(date.month)

    (_, last) = calendar.monthrange(date.year, date.month)

    start_at = datetime.datetime(date.year, date.month, 1).astimezone(datetime.timezone.utc)
    end_at = datetime.datetime(date.year, date.month, last, 23, 59, 59).astimezone(datetime.timezone.utc)

    qs = urlencode({
        'period': 'month',
        'filter_by': 'metricName:age_band',
        'collect': 'count:sum',
        'group_by': 'value',
        'start_at': start_at.isoformat(),
        'end_at': end_at.isoformat(),
        'format': 'json',
    })

    url = f'{base_url}?{qs}'
    print(f'Making request to {url}')

    req =  request.Request(base_url + '?' + qs)
    resp = request.urlopen(req)

    payload = json.load(resp)
    data = payload["data"]
    key = f'{date.year}-{date.month}'

    metrics[date.year] = metrics.get(date.year) or {}

    for segment in data:

        if segment.get('value') in age_groups:

            year_stats = metrics[date.year]

            year_stats[date.month] = year_stats.get(date.month) or 0
            year_stats[date.month] += segment.get('count:sum')

writer.writerow(headers)

for year, value in metrics.items():

    values = list(value.values())

    row = [year] + values
    writer.writerow(row)

Requires Python 3 will create file in folder with the final stats called "metrics.csv" - create graph by importing into excel