[Python pandas] 데이터프레임(dataframe)에서 그룹 기준으로 누적계산하기

소개

# 데이터 프레임에서 특정 칼럼이 유지될 동안 대상 칼럼의 값을 누적합니다.
# index 번호 기준으로 내려가다가 값이 바뀌면 해당 group에서 다시 시작합니다.
# 이전 group 값이 다시 시작될 경우 해당 값에서 다시 누적 계산이 시작됩니다.

자료 출처

# https://stackoverflow.com/questions/32847800/how-can-i-use-cumsum-within-a-group-in-pandas

라이브러리 및 데이터 불러오기

# 라이브러리
import pandas as pd
 
# 데이터
mock_data = pd.read_csv('MOCK_DATA.csv')
mock_data.head(3)

	id	ssn	first_name	last_name	email	gender	ip_address	city	country	car_make	car_model
0	1	352-83-7834	Josselyn	Commuzzo	jcommuzzo0@shop-pro.jp	Female	NaN	Aībak	Afghanistan	GMC	Yukon XL 2500
1	2	129-55-2802	Aksel	Cubbin	acubbin1@rakuten.co.jp	Male	NaN	Gaya	Nigeria	Cadillac	CTS
2	3	421-78-0056	Marwin	Vagg	NaN	Male	NaN	Huangjiakou	China	Chevrolet	Tahoe

누적할 대상 값을 임의로 생성하기(여기선 1을 값으로 삽입)

mock_data['count'] = 1
mock_data.head()

	id	ssn	first_name	last_name	email	gender	ip_address	city	country	car_make	car_model	count
0	1	352-83-7834	Josselyn	Commuzzo	jcommuzzo0@shop-pro.jp	Female	NaN	Aībak	Afghanistan	GMC	Yukon XL 2500	1
1	2	129-55-2802	Aksel	Cubbin	acubbin1@rakuten.co.jp	Male	NaN	Gaya	Nigeria	Cadillac	CTS	1
2	3	421-78-0056	Marwin	Vagg	NaN	Male	NaN	Huangjiakou	China	Chevrolet	Tahoe	1
3	4	NaN	Michele	Freed	NaN	Male	95.30.236.76	Ferrol	Spain	Volvo	NaN	1
4	5	821-40-7635	Skip	Sallan	ssallan4@nymag.com	Male	200.83.222.220	Sheffield	United Kingdom	GMC	Canyon	1

gender 칼럼을 기준으로 count 칼럼을 값을 계속 누적함(gender 칼럼 값이 바뀌면 새롭게 누적 시작)

mock_data['cumsum'] = mock_data.groupby('gender')['count'].cumsum()
mock_data.head(20)

	id	ssn	first_name	last_name	email	gender	ip_address	city	country	car_make	car_model	count	cumsum
0	1	352-83-7834	Josselyn	Commuzzo	jcommuzzo0@shop-pro.jp	Female	NaN	Aībak	Afghanistan	GMC	Yukon XL 2500	1	1
1	2	129-55-2802	Aksel	Cubbin	acubbin1@rakuten.co.jp	Male	NaN	Gaya	Nigeria	Cadillac	CTS	1	1
2	3	421-78-0056	Marwin	Vagg	NaN	Male	NaN	Huangjiakou	China	Chevrolet	Tahoe	1	2
3	4	NaN	Michele	Freed	NaN	Male	95.30.236.76	Ferrol	Spain	Volvo	NaN	1	3
4	5	821-40-7635	Skip	Sallan	ssallan4@nymag.com	Male	200.83.222.220	Sheffield	United Kingdom	GMC	Canyon	1	4
5	6	854-88-6296	Belia	Cushworth	bcushworth5@blinklist.com	Female	255.52.106.120	Nueve de Julio	Argentina	Dodge	Ram	1	2
6	7	650-58-6287	Thane	Baltzar	tbaltzar6@infoseek.co.jp	Male	89.251.85.176	Kikuchi	Japan	Pontiac	Firefly	1	5
7	8	738-62-4156	Amery	Sizeland	asizeland7@yale.edu	Male	NaN	Gunungmalang Satu	Indonesia	Lexus	LX	1	6
8	9	NaN	Forest	Gambrell	fgambrell8@a8.net	Male	215.69.63.55	Goundi	Chad	Nissan	NaN	1	7
9	10	344-02-8451	Fernande	Mordey	NaN	Female	NaN	Nurlat	Russia	Dodge	Caravan	1	3
10	11	586-17-7170	Damon	Tine	dtinea@toplist.cz	Male	231.66.76.104	Gangou	China	NaN	Tiguan	1	8
11	12	306-11-6909	Otis	Harriott	oharriottb@fema.gov	Male	NaN	Francisco Morato	Brazil	Chevrolet	Corvette	1	9
12	13	176-22-8123	Xever	MacLachlan	xmaclachlanc@msu.edu	Male	NaN	Zalewo	Poland	Land Rover	Discovery	1	10
13	14	150-25-6348	Roze	Bestwick	rbestwickd@creativecommons.org	Female	NaN	Annopol	Poland	Ford	F250	1	4
14	15	518-93-3198	Rafael	Commander	rcommandere@google.pl	Male	67.252.156.166	Mandepa Barat	Indonesia	Buick	Park Avenue	1	11
15	16	114-34-3979	Anett	Crocket	NaN	Female	NaN	Hepo	China	NaN	9-3	1	5
16	17	200-90-4726	Stacee	Glass	sglassg@cargocollective.com	Female	78.236.229.147	Passa Quatro	Brazil	Mitsubishi	Galant	1	6
17	18	754-80-7014	Luca	Ledes	NaN	Male	141.214.157.140	Sigay	Philippines	Maserati	GranSport	1	12
18	19	NaN	Che	Marchelli	cmarchellii@360.cn	Male	27.46.24.17	Palaiochóri	Greece	Mitsubishi	NaN	1	13
19	20	258-76-4616	Pascal	Andreutti	pandreuttij@usda.gov	Male	152.27.178.79	Além do Rio	Portugal	Chevrolet	Impala	1	14