我的目标是对“matr”进行排序,按列c1排序,并保留其中满足c2 = 1的唯一值(c1)。例如,从以下代码...
c1 = c("a",'a','a','b','b','b','b','c','c')
c2 = c(1,1,0,1,1,0,1,0,0)
matr = as.data.frame(cbind(c1,c2))
one = sqldf('select distinct(c1),c2 from matr where c2 = 1')
vs = sqldf('select distinct(c1),c0,c2 from matr group by c1')
sqldf('select matr.*,one.* from matr
left outer join one
where one.c1 = matr.c1')
到达:
c1 c2
a 1
b 1
c 0
由于某些原因,在左连接中我失去了行c。我只能通过其他连接到达(此结果)。
c1 c2
a 1
b 1