我需要计算pandas DataFrame中每个产品的activity_months数量。这是目前我的数据和代码:
from pandas import DataFrame
from datetime import datetime
data = [
('product_a','08/31/2013')
,('product_b','08/31/2013')
,('product_c','08/31/2013')
,('product_a','09/30/2013')
,('product_b','09/30/2013')
,('product_c','09/30/2013')
,('product_a','10/31/2013')
,('product_b','10/31/2013')
,('product_c','10/31/2013')
]
product_df = DataFrame( data, columns=['prod_desc','activity_month'])
for index, row in product_df.iterrows():
row['activity_month']= datetime.strptime(row['activity_month'],'%m/%d/%Y')
product_df.loc[index, 'activity_month'] = datetime.strftime(row['activity_month'],'%Y-%m-%d')
product_df = product_df.sort(['prod_desc','activity_month'])
product_df['month_num'] = product_df.groupby(['prod_desc']).size()
然而,这会返回月份数的NaN值。
这是我想要得到的:
prod_desc activity_month month_num
product_a 2014-08-31 1
product_a 2014-09-30 2
product_a 2014-10-31 3
product_b 2014-08-31 1
product_b 2014-09-30 2
product_b 2014-10-31 3
product_c 2014-08-31 1
product_c 2014-09-30 2
product_c 2014-10-31 3
month_num
是否只是等于activity_month
中的月份?你的最终目标是什么? - ojdo