來自慕課網《R語言之數據可視化》課程3-6代碼如下set.seed(1)x <- rnorm(100)f <- rep(0:1, each = 50)y <- x + f - f*x + rnorm(100, sd = 0.5)f <- factor(f, labels = c("Group1", "Group2"))xyplot(y~x | f, layout(2,1))之后顯示錯誤，錯誤代碼：Error in layout(2, 1) : layout matrix must contain at least one referenceto each of the values {1 ... 2}而課程視頻里面的老師用這個代碼就沒有問題，不知道我這里問題出在哪里，希望指教！