subset函数

subset(dataset , subset , select )

dataset 是 要进行操作的数据集

subset 是对数据的某些字段进行操作

select 选取要显示的字段

hightech【数据集】

aa = subset(hightech,year==2001&province=="北京",select = c("year","province","PAT"))

bb = subset(hightech,year==2001|province=="北京",select = c("year","province","NPO"))