Data Mining and Processing for fun and profit

Tutorial on data mining given at PyConZA16

Transcript

1. Data Mining and Processing for fun and profit PyConZA - Cape Town, SA Oct 7, 2016 by Reuben Cummings @reubano #PyConZA16
2. Who am I? •Managing Director, Nerevu Development •Lead organizer of Arusha Coders •Author of several popular packages @reubano #PyConZA16
3. Topics & Format •data and data mining •code samples and interactive exercises •hands-on (don't be a spectator) @reubano #PyConZA16
4. what is data?
5. Organization country capital S Africa Joburg Tanzania Dodoma Rwanda Kigali structured unstructured "O God of all creation. Bless this our land and nation. Justice be our shield..."
6. Storage flat/text binary greeting,loc hello,world good bye,moon welcome,stars what's up,sky 00105e0 b0e6 04... 00105f0 e4e7 04... 0010600 0be8 04... 00105f0 e4e7 04... 00105e0 b0e6 04...
7. Organization vs Storage structured unstructured binary flat/text good! bad!
8. what is data mining?
9. Obtaining Data APIs websites feeds databases filesystems
10. Normalizing Data S Africa Tanzania Rwanda Joburg Dodoma Kigali 1961 1961 1962
11. Normalizing Data country capital independence S Africa Joburg 1961 Tanzania Dodoma 1961 Rwanda Kigali 1962
12. Visualizing Data 0 25 50 75 100 1930 1940 1950 1960 Cumulative Independent African Countries* * Note: above data is made up
13. so what!
14. Mint (mint.com)
15. Plotly (plot.ly)
16. Parsely (parsely.com)
17. You might not need pandas
18. IPython Demo bit.ly/data-pyconza16 (examples)
19. obtaining json
20. Code for South Africa (data.code4sa.org)
21. >>> from urllib.request import urlopen >>> from ijson import items >>> >>> # crime-summary.json in repo >>> url = 'http://data.code4sa.org/resource/qtx7- xbrs.json' >>> f = urlopen(url) >>> data = items(f, 'item') >>> next(data) {'station': 'Aberdeen', 'sum_2014_2015': '1153'}
22. reading csv
23. >>> from csv import DictReader >>> from io import open >>> from os import path as p >>> {'Crime': 'All theft not mentioned elsewhere', 'Incidents': '3397', 'Police Station': 'Durban Central', 'Province': 'KZN', 'Year': '2014'} >>> url = p.abspath('filtered-crime-stats.csv') >>> f = open(url) >>> data = DictReader(f) >>> next(data)
24. reading excel
25. >>> from xlrd import open_workbook >>> >>> url = p.abspath('filtered-crime-stats.xlsx') >>> book = open_workbook(url) >>> sheet = book.sheet_by_index(0) >>> sheet.row_values(0) ['Province', 'Police Station', 'Crime', 'Year', 'Incidents'] >>> sheet.row_values(1) ['KZN', 'Durban Central', 'All theft not mentioned elsewhere', 2014.0, 3397.0]
26. screen scraping
27. >>> import requests >>> from bs4 import BeautifulSoup >>> >>> url = 'https://github.com/reubano/pyconza-tutorial/ raw/master/migrants.html' >>> r = requests.get(url) >>> soup = BeautifulSoup(r.text, 'html.parser') >>> >>> def get_data(table): ... for row in table.findAll('tr')[1:]: ... header = row.findAll('th') ... td = row.findAll('td') ... columns = header or td ... yield [c.getText() for c in columns]
28. >>> table = soup.find('table') >>> data = get_data(table) >>> next(data) ['Mediterranean', '82', '346', ... ] >>> next(data) ['', 'January', 'February', ... ]
29. aggregating data
30. >>> import itertools as it >>> >>> records = [ ... {'a': 'item', 'amount': 200}, ... {'a': 'item', 'amount': 300}, ... {'a': 'item', 'amount': 400}] ... {'a': 'item', 'amount': 900} >>> key = 'amount' >>> first = records[0] >>> value = sum(r.get(key, 0) for r in records) >>> dict(it.chain(first.items(), [(key, value)]))
31. grouping data
32. >>> import itertools as it >>> from operator import itemgetter >>> >>> records = [ ... {'item': 'a', 'amount': 200}, ... {'item': 'b', 'amount': 200}, ... {'item': 'c', 'amount': 400}] >>> (200, [{'amount': 200, 'item': 'a'}, {'amount': 200, 'item': 'b'}]) >>> keyfunc = itemgetter('amount') >>> sorted_records = sorted(records, key=keyfunc) >>> grouped = it.groupby(sorted_records, keyfunc) >>> data = ((key, list(group)) for key, group in grouped) >>> next(data)
33. exercise #1
34. IPython Demo bit.ly/data-pyconza16 (exercises)
35. lowest crime per province
36. FS ('All theft not mentioned elsewhere', 2940) GP ('Drug-related crime', 5229) KZN ('Drug-related crime', 4571) WC ('Common assault', 2188)
37. IPython Demo bit.ly/data-pyconza16 (solutions)
38. >>> url = p.abspath('filtered-crime-stats.csv') >>> f = open(url) >>> data = DictReader(f) >>> keyfunc = itemgetter('Province') >>> records = sorted(data, key=keyfunc) >>> grouped = groupby(records, keyfunc) >>> from csv import DictReader >>> from io import open >>> from os import path as p >>> from itertools import groupby >>> from operator import itemgetter >>>
39. >>> for key, group in grouped: ... print(key) ... keyfunc = itemgetter('Crime') ... sub_records = sorted(group, key=keyfunc) ... sub_grouped = groupby(sub_records, keyfunc) ... low_count, low_key = 0, None ... ... for sub_key, sg in sub_grouped: ... count = sum(int(s['Incidents']) for s in sg) ... if not low_count or count < low_count: ... low_count = count ... low_key = sub_key ... ... print((low_key, low_count))
40. introducing meza github.com/reubano/meza
41. IPython Demo bit.ly/data-pyconza16 (meza)
42. reading data
43. >>> from urllib.request import urlopen >>> from meza.io import read_json >>> >>> # crime-summary >>> url = 'http://data.code4sa.org/resource/qtx7- xbrs.json' >>> f = urlopen(url) >>> records = read_json(f) >>> next(records) {'station': 'Aberdeen', 'sum_2014_2015': '1153'} >>> next(records) {'station': 'Acornhoek', 'sum_2014_2015': '5047'}
44. >>> from io import StringIO >>> from meza.io import read_csv >>> >>> f = StringIO('greeting,location\nhello,world\n') >>> records = read_csv(f) >>> next(records) {'greeting': 'hello', 'location': 'world'}
45. reading more data
46. >>> from os import path as p >>> from meza import io >>> >>> url = p.abspath('crime-summary.json') >>> records = io.read(url) >>> next(records) {'station': 'Aberdeen', 'sum_2014_2015': '1153'} >>> url2 = p.abspath('filtered-crime-stats.csv') >>> records = io.join(url, url2) >>> next(records) {'station': 'Aberdeen', 'sum_2014_2015': '1153'}
47. reading excel
48. >>> from io import open >>> from meza.io import read_xls >>> >>> url = p.abspath('filtered-crime-stats.xlsx') >>> records = read_xls(url, sanitize=True) >>> next(records) {'crime': 'All theft not mentioned elsewhere', 'incidents': '3397.0', 'police_station': 'Durban Central', 'province': 'KZN', 'year': '2014.0'}
49. screen scraping
50. >>> from meza.io import read_html >>> >>> url = p.abspath('migrants.html') >>> records = read_html(url, sanitize=True) >>> next(records) {'': 'Mediterranean', 'april': '1,244', 'august': '684', 'december': '203', 'february': '346', 'january': '82', 'july': '230', 'june': '\xa010', ... 'total_to_date': '3,760'}
51. aggregating data
52. >>> from meza.process import aggregate >>> >>> records = [ ... {'a': 'item', 'amount': 200}, ... {'a': 'item', 'amount': 300}, ... {'a': 'item', 'amount': 400}] ... >>> aggregate(records, 'amount', sum) {'a': 'item', 'amount': 900}
53. grouping data
54. >>> from meza.process import group >>> >>> records = [ ... {'item': 'a', 'amount': 200}, ... {'item': 'b', 'amount': 200}, ... {'item': 'c', 'amount': 400}] >>> >>> grouped = group(records, 'amount') >>> next(grouped) (200, [{'amount': 200, 'item': 'a'}, {'amount': 200, 'item': 'b'}])
55. type casting
56. >>> from meza.io import read_csv >>> from meza.process import detect_types, type_cast >>> >>> url = p.abspath('filtered-crime-stats.csv') >>> raw = read_csv(url) >>> records, result = detect_types(raw) >>> result['types'] [{'id': 'Incidents', 'type': 'int'}, {'id': 'Crime', 'type': 'text'}, {'id': 'Province', 'type': 'text'}, {'id': 'Year', 'type': 'int'}, {'id': 'Police Station', 'type': 'text'}]
57. >>> casted = type_cast(records, **result) >>> next(casted) {'Crime': 'All theft not mentioned elsewhere', 'Incidents': 3397, 'Police Station': 'Durban Central', 'Province': 'KZN', 'Year': 2014}
58. normalizing data
59. >>> from meza.process import normalize >>> >>> records = [ ... {'color': 'blue', 'setosa': 5, 'versi': 6}, ... {'color': 'red', 'setosa': 5, 'versi': 6}] >>> kwargs = { ... 'data': 'length', ... 'column':'species', ... 'rows': ['setosa', 'versi']} >>> data = normalize(records, **kwargs) >>> next(data) {'color': 'blue', 'length': 5, 'species': 'setosa'}
60. head to head pandas meza installation complex simple size large small memory usage high low speed fast fast* functions very many many input/output many many
61. exercise #2
62. IPython Demo bit.ly/data-pyconza16 (exercises)
63. lowest crime per province
64. {'Police Station': 'Park Road', 'Incidents': 2940, 'Province': 'FS', 'Crime': 'All theft not mentioned elsewhere', 'Year': 2014} {'Police Station': 'Eldorado Park', 'Incidents': 5229, 'Province': 'GP', 'Crime': 'Drug-related crime', 'Year': 2014} {'Police Station': 'Durban Central', 'Incidents': 4571, 'Province': 'KZN', 'Crime': 'Drug-related crime', 'Year': 2014} {'Police Station': 'Mitchells Plain', 'Incidents': 2188, 'Province': 'WC', 'Crime': 'Common assault', 'Year': 2014}
65. IPython Demo bit.ly/data-pyconza16 (solutions)
66. >>> url = p.abspath('filtered-crime-stats.csv') >>> raw = read_csv(url) >>> records, result = detect_types(raw) >>> casted = type_cast(records, **result) >>> grouped = group(casted, 'Province') >>> from meza.io import read_csv >>> from meza.process import ( ... aggregate, group, detect_types, type_cast) >>>
67. >>> for key, _group in grouped: ... sub_grouped = group(_group, 'Crime') ... aggs = ( ... aggregate(sg[1], 'Incidents', sum) ... for sg in sub_grouped) ... ... keyfunc = itemgetter('Incidents') ... print(min(aggs, key=keyfunc))
68. exercise #3
69. incidents per person per province
70. Thanks! Reuben Cummings reubano@gmail.com https://github.com/reubano/meza #pyconza2016 @reubano