图中数据框army的索引设置为origin
1.army.loc[‘Maine’]返回值 Series 类型
regiment Dragoons company 1st deaths 43 battles 4 size 1592 veterans 73 readiness 2 armored 0 deserters 3 Name: Maine, dtype: object
2.army.loc[[‘Maine’,‘Alaska’]]返回值是 Dataframe 类型
3.同时对列进行选取
army.loc[[“Maine”, “Alaska”], [“deaths”, “size”, “deserters”]]
deaths size deserters origin Maine 43 1592 3 Alaska 523 987 24
4.使用 " : " 对下标进行切片选择
army.loc[“Maine”:“Alaska”, [“deaths”, “size”, “deserters”]]
注意中括号
deaths size deserters origin Maine 43 1592 3 Iowa 234 1006 4 Alaska 523 987 24
