创建一个多指标由MultiIndex.from_product（），然后
set_index()，
reindex()，
reset_index()。
import pandas as pdimport ioall_person_ids = [0, 1, 2]all_statuses = ['pass', 'fail']all_years = [1980, 1981, 1982]df = pd.read_csv(io.BytesIO("""person_id status year count0pass 1980 40fail 1982 11pass 1981 2"""), delim_whitespace=True)names = ["person_id", "status", "year"]mind = pd.MultiIndex.from_product( [all_person_ids, all_statuses, all_years], names=names)df.set_index(names).reindex(mind, fill_value=0).reset_index()
