我的目标是采用'matr',按列c1对其进行排序,并保持唯一(c1),其中c2 = 1.例如,从此代码中...
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
出于某种原因,我在左连接中丢失了行c.我只能到达(通过其他联接)
c1 c2
a 1
b 1