[英]How to create a new dataframe column using values and groupings from other rows and columns in pandas?
[英]How to create a new row in pandas dataframe by dividing values in a specific column between two rows and keeping other columns intact?
我有一个 pandas dataframe df
,如下所示:
Country Continent Capital City Year Indicator Value Unit
0 Nepal Asia Kathmandu 2015 Population 3 million
1 Nepal Asia Kathmandu 2020 Population 5 million
2 Germany Europe Berlin 2015 Population 4 million
3 Germany Europe Berlin 2020 Population 6 million
df.to_dict()
如下图所示:
{'Country': {0: 'Nepal', 1: 'Nepal', 2: 'Germany', 3: 'Germany'},
'Continent': {0: 'Asia', 1: 'Asia', 2: 'Europe', 3: 'Europe'},
'Capital City': {0: 'Kathmandu', 1: 'Kathmandu', 2: 'Berlin', 3: 'Berlin'},
'Year': {0: 2015, 1: 2020, 2: 2015, 3: 2020},
'Indicator': {0: 'Population',
1: 'Population',
2: 'Population',
3: 'Population'},
'Value': {0: 3, 1: 5, 2: 4, 3: 6},
'Unit': {0: 'million', 1: 'million', 2: 'million', 3: 'million'}}
dataframe 分别包含尼泊尔和德国两国首都 2015 年和 2020 年的人口数据。
我想创建两个新行,显示 2015 年到 2020 年之间的人口增长率(例如,尼泊尔的 5/3 即 1.67 和德国的 6/4 即 1.5)。 这些行需要位于相同的 dataframe 中。 在新行中,Country、Continent 和 Capital City 列对于各自的国家/地区应保持不变。 年份值保持2020年,指标名称需为“人口增长率”,单位需为“乘以2015年值”。 它应该如下所示:
Country Continent Capital City Year Indicator Value Unit
0 Nepal Asia Kathmandu 2015 Population 3 million
1 Nepal Asia Kathmandu 2020 Population 5 million
2 Germany Europe Berlin 2015 Population 4 million
3 Germany Europe Berlin 2020 Population 6 million
4 Nepal Asia Kathmandu 2020 Population growth rate 1.666667 times 2015 value
5 Germany Europe Berlin 2020 Population growth rate 1.5 times 2015 value
如何在原始 dataframe 中附加人口增长率的情况下创建这两个新行?
用groupby
然后append
out = df.groupby(['Country','Continent','Capital City']).agg({'Year':'last','Value':lambda x : x.iloc[-1]/x.iloc[0]}).reset_index()
out['Indicator'] = 'Population growth rate'
df = df.append(out)
df
Out[16]:
Country Continent Capital City ... Indicator Value Unit
0 Nepal Asia Kathmandu ... Population 3.000000 million
1 Nepal Asia Kathmandu ... Population 5.000000 million
2 Germany Europe Berlin ... Population 4.000000 million
3 Germany Europe Berlin ... Population 6.000000 million
0 Germany Europe Berlin ... Population growth rate 1.500000 NaN
1 Nepal Asia Kathmandu ... Population growth rate 1.666667 NaN
[6 rows x 7 columns]
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