Plot interest rate data from Bank of England

interest-rate.py

import re
import datetime
import matplotlib.pyplot as plt


def parse_data_string(data_string):
    pattern = r"(\d{1,2})\s([a-zA-Z]{3})\s(\d{2})\s(\d+\.\d+)"
    match = re.match(pattern, data_string)

    if match:
        day = int(match.group(1))
        month_str = match.group(2)
        year = int(match.group(3))
        rate = float(match.group(4))

        # Handle years with only two digits
        if year >= 0 and year <= 24:
            year += 2000
        else:
            year += 1900

        date = datetime.datetime.strptime(f"{day} {month_str} {year}", "%d %b %Y")
        return date, rate

    return None

data = '''
23 Mar 23	4.25
02 Feb 23	4.00
15 Dec 22	3.50
03 Nov 22	3.00
22 Sep 22	2.25
04 Aug 22	1.75
16 Jun 22	1.25
05 May 22	1.00
17 Mar 22	0.75
03 Feb 22	0.50
16 Dec 21	0.25
19 Mar 20	0.10
11 Mar 20	0.25
02 Aug 18	0.75
02 Nov 17	0.50
04 Aug 16	0.25
05 Mar 09	0.50
05 Feb 09	1.00
08 Jan 09	1.50
04 Dec 08	2.00
06 Nov 08	3.00
08 Oct 08	4.50
10 Apr 08	5.00
07 Feb 08	5.25
06 Dec 07	5.50
05 Jul 07	5.75
10 May 07	5.50
11 Jan 07	5.25
09 Nov 06	5.00
03 Aug 06	4.75
04 Aug 05	4.50
05 Aug 04	4.75
10 Jun 04	4.50
06 May 04	4.25
05 Feb 04	4.00
06 Nov 03	3.75
10 Jul 03	3.50
06 Feb 03	3.75
08 Nov 01	4.00
04 Oct 01	4.50
18 Sep 01	4.75
02 Aug 01	5.00
10 May 01	5.25
05 Apr 01	5.50
08 Feb 01	5.75
10 Feb 00	6.00
13 Jan 00	5.75
04 Nov 99	5.50
08 Sep 99	5.25
10 Jun 99	5.00
08 Apr 99	5.25
04 Feb 99	5.50
07 Jan 99	6.00
10 Dec 98	6.25
05 Nov 98	6.75
08 Oct 98	7.25
04 Jun 98	7.50
06 Nov 97	7.25
07 Aug 97	7.00
10 Jul 97	6.75
06 Jun 97	6.50
06 May 97	6.25
30 Oct 96	5.94
06 Jun 96	5.69
08 Mar 96	5.94
18 Jan 96	6.13
13 Dec 95	6.38
02 Feb 95	6.63
07 Dec 94	6.13
12 Sep 94	5.63
08 Feb 94	5.13
23 Nov 93	5.38
26 Jan 93	5.88
13 Nov 92	6.88
16 Oct 92	7.88
22 Sep 92	8.88
05 May 92	9.88
04 Sep 91	10.38
12 Jul 91	10.88
24 May 91	11.38
12 Apr 91	11.88
22 Mar 91	12.38
27 Feb 91	12.88
13 Feb 91	13.38
08 Oct 90	13.88
06 Oct 89	14.88
08 Sep 89	13.75
04 Sep 89	13.88
31 Aug 89	13.84
25 May 89	13.75
25 Nov 88	12.88
25 Aug 88	11.88
08 Aug 88	10.88
21 Jul 88	10.38
07 Jul 88	9.88
24 Jun 88	8.88
10 Jun 88	8.38
03 Jun 88	7.88
17 May 88	7.38
08 Apr 88	7.88
17 Mar 88	8.38
01 Feb 88	8.88
03 Dec 87	8.38
04 Nov 87	8.88
23 Oct 87	9.38
06 Aug 87	9.88
08 May 87	8.88
28 Apr 87	9.38
18 Mar 87	9.88
09 Mar 87	10.38
15 Oct 86	10.88
23 May 86	9.88
18 Apr 86	10.38
11 Apr 86	10.88
19 Mar 86	11.38
15 Jan 86	12.38
26 Jul 85	11.38
11 Jul 85	11.88
19 Apr 85	12.38
28 Mar 85	12.88
20 Mar 85	13.38
28 Jan 85	13.88
14 Jan 85	11.88
23 Nov 84	9.50
19 Nov 84	9.75
05 Nov 84	10.00
17 Aug 84	10.50
16 Aug 84	10.75
09 Aug 84	11.00
08 Aug 84	11.50
11 Jul 84	12.00
06 Jul 84	10.00
29 Jun 84	8.88
10 May 84	9.06
14 Mar 84	8.56
07 Mar 84	8.81
03 Oct 83	9.06
10 Aug 83	9.56
09 Aug 83	9.44
14 Jun 83	9.56
13 Jun 83	9.81
14 Apr 83	10.06
13 Apr 83	10.31
15 Mar 83	10.56
12 Jan 83	11.00
26 Nov 82	10.00
02 Nov 82	9.13
01 Nov 82	9.38
12 Oct 82	9.63
30 Sep 82	10.13
29 Sep 82	10.25
28 Sep 82	10.38
27 Sep 82	10.50
27 Aug 82	10.63
26 Aug 82	10.88
25 Aug 82	11.00
24 Aug 82	11.13
17 Aug 82	11.25
16 Aug 82	11.38
04 Aug 82	11.50
02 Aug 82	11.56
30 Jul 82	11.63
29 Jul 82	11.75
28 Jul 82	11.81
26 Jul 82	11.94
21 Jul 82	12.06
13 Jul 82	12.13
12 Jul 82	12.25
09 Jul 82	12.50
08 Jun 82	12.63
20 Apr 82	13.13
19 Apr 82	13.00
16 Apr 82	13.13
10 Mar 82	13.25
25 Feb 82	13.63
22 Feb 82	13.81
22 Jan 82	13.88
21 Jan 82	14.00
20 Jan 82	14.13
19 Jan 82	14.25
18 Jan 82	14.31
04 Dec 81	14.38
25 Nov 81	14.56
09 Nov 81	14.63
06 Nov 81	15.06
28 Oct 81	15.13
12 Oct 81	15.00
15 Sep 81	14.00
25 Aug 81	12.69
11 Mar 81	12.00
25 Nov 80	14.00
03 Jul 80	16.00
15 Nov 79	17.00
13 Jun 79	14.00
05 Apr 79	12.00
01 Mar 79	13.00
08 Feb 79	14.00
09 Nov 78	12.50
08 Jun 78	10.00
15 May 78	9.00
08 May 78	8.75
12 Apr 78	7.50
09 Jan 78	6.50
28 Nov 77	7.00
17 Oct 77	5.00
10 Oct 77	5.50
19 Sep 77	6.00
12 Sep 77	6.50
15 Aug 77	7.00
08 Aug 77	7.50
16 May 77	8.00
02 May 77	8.25
25 Apr 77	8.75
18 Apr 77	9.00
12 Apr 77	9.25
31 Mar 77	9.50
21 Mar 77	10.50
10 Mar 77	11.00
03 Feb 77	12.00
31 Jan 77	12.25
24 Jan 77	13.25
10 Jan 77	14.00
29 Dec 76	14.25
20 Dec 76	14.50
22 Nov 76	14.75
07 Oct 76	15.00
13 Sep 76	13.00
24 May 76	11.50
26 Apr 76	10.50
08 Mar 76	9.00
01 Mar 76	9.25
09 Feb 76	9.50
02 Feb 76	10.00
26 Jan 76	10.50
19 Jan 76	10.75
05 Jan 76	11.00
29 Dec 75	11.25
01 Dec 75	11.50
17 Nov 75	11.75
06 Oct 75	12.00
28 Jul 75	11.00
05 May 75	10.00
21 Apr 75	9.75
24 Mar 75	10.00
10 Mar 75	10.25
17 Feb 75	10.50
10 Feb 75	10.75
27 Jan 75	11.00
20 Jan 75	11.25
'''.strip().split('\n')

dates = []
rates = []

for line in data:
    date, rate = parse_data_string(line)
    dates.append(date)
    rates.append(rate)

start_date = datetime.datetime(1975, 1, 1)
dates_filtered = [date for date in dates if date >= start_date]
rates_filtered = [rate for date, rate in zip(dates, rates) if date >= start_date]

with plt.xkcd():
	plt.plot(dates_filtered, rates_filtered)
	plt.xlabel('Date')
	plt.ylabel('Bank Rate')
	plt.title('Bank Rate History (1970 onwards)')
	plt.xticks(rotation=45)
	plt.grid()
	plt.tight_layout()
plt.show()