如何删除R中colMeans（）函数的非数值？

Question

这是一行，

colMeans3 <- colMeans(grade3, na.rm=TRUE)

和R说

Error in colMeans(grades3, na.rm = TRUE) : 'x' must be numeric

Answer 1

子集grade3仅包含数字变量。

grade3 <- data.frame(a = runif(10), b = rnorm(10), c = letters[1:10])
colMeans(grade3)

find.numeric <- sapply(grade3, is.numeric)
colMeans(grade3[, find.numeric])
        a         b 
0.4675017 0.1642704