x <- 1:100
y <- vector()
for (i in x) {
if(i <= 5) y[i] <- f(x[i])#此处f()表示y与x的函数关系式
else y[i] <- y[i-5]
}
-Usage
aggregate(x, by, FUN, ..., simplify = TRUE, drop = TRUE)
与tapply类似,但是x可以为data.frame或矩阵;
-Arguments
by
a list of grouping elements, each as long as the variables in the data frame x. The
elements are coerced to factors before use.
-Example
-Usage
by(data, INDICES, FUN, ..., simplify = TRUE)
-Example
将warpbreaks的一二列,根据tension这一列的(L、M、H)运行summary
aggregate与by的区别 :aggregate是对x的每一列分别根据因子进行分组计算,而by是根据因子将data整个分成几个小的data.frame,然后进行运算;