这是一个与我可以找到的类似措辞的问题相反的问题,例如:
- Pandas-按一列分组,按另一列排序,从第三列获取值
- 如何按一列分组并对另一列的值进行排序
说,我有这个DataFrame:
import pandas as pd
df = pd.DataFrame({
'model': ['Punto', 'Doblo', 'Panda', 'Doblo','Punto', 'Tipo'] ,
'timestamp': ['20200124_083155', '20200124_122052', '20200124_134350', '20200124_150801', '20200124_163540', '20200124_195955']
})
print(df)
打印出来:
model timestamp
0 Punto 20200124_083155
1 Doblo 20200124_122052
2 Panda 20200124_134350
3 Doblo 20200124_150801
4 Punto 20200124_163540
5 Tipo 20200124_195955
我想得到的是:首先按时间戳排序;然后按照出现的顺序,按出现的顺序分组,但没有额外的";组";pandas.groupby
子句将添加的列;也就是说,我想获得最终输出:
model timestamp
0 Punto 20200124_083155
1 Punto 20200124_163540
2 Doblo 20200124_122052
3 Doblo 20200124_150801
4 Panda 20200124_134350
5 Tipo 20200124_195955
我怎样才能做到这一点?
我认为这是可能的,通过排序的类别,在第一步中按排序的timestamp
值设置顺序,然后按DataFrame.sort_values
:按两列排序
c = df.sort_values('timestamp')['model'].unique()
df['model'] = pd.Categorical(df['model'], ordered=True, categories=c)
df = df.sort_values(['model','timestamp'])
print (df)
model timestamp
0 Punto 20200124_083155
4 Punto 20200124_163540
1 Doblo 20200124_122052
3 Doblo 20200124_150801
2 Panda 20200124_134350
5 Tipo 20200124_195955