warning :: Coercing LHS to a list
df<-iris dtrace <- apply(df, 1,function(x){ tt<-x[3] tt$wid <- x[1] return(tt) }) #dtrace <- ldply(dtrace, rbind)[,-1] result<-rbindlist(dtrace, use.names=TRUE, fill=TRUE) result
df<-iris dtrace <- apply(df, 1,function(x){ tt<-c(x[3],wid=x[4]) return(tt) }) result<-t(dtrace)
left hand side
In tt$wid <- x[1]
: Coercing LHS to a list
$연산자를 matrix의 subset하기위해 사용하면 안된다. ( 새로운 컬럼을 추가할때 쓴다)
dtrace <- apply(df, 1,function(x){ tt<-x[3] tt$wid <- x[1] return(tt) })
> class(dtrace) [1] "list" > dim(dtrace) NULL
> head(dtrace) [[1]] [[1]]$Petal.Length [1] 1.4 [[1]]$wid Sepal.Length 5.1 [[2]] [[2]]$Petal.Length [1] 1.4 [[2]]$wid Sepal.Length 4.9 [[3]] [[3]]$Petal.Length [1] 1.3 [[3]]$wid Sepal.Length 4.7