R 计算组内和组间的平均差异

我有两组值，如下所示：

x <- as.vector(c(1, 2, 3, 2, 1))
y <- as.vector(c(7, 7, 8, 9, 9))

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x一种可能性是：

xy_diff <- abs(sapply(x, "-", y))
sum(xy_diff)/(dim(xy_diff)[1]*dim(xy_diff)[2])

[1] 6.2

x_diff <- abs(sapply(x, "-", x))
x_diff <- x_diff[upper.tri(x_diff)]
sum(x_diff/length(x_diff))

[1] 1

y_diff <- abs(sapply(y, "-", y))
y_diff <- y_diff[upper.tri(y_diff)]
sum(y_diff/length(y_diff))

[1] 1.2

xy_diff