var() function calculates the variance of a vector.
var(x, y = NULL, na.rm = FALSE, use)
cov(x, y = NULL, use = "everything",
method = c("pearson", "kendall", "spearman"))
cov2cor(V)
x: numeric vector, matrix or data framey: numeric vector, matrix or data frame with compatiable dimensions to x, default is NULLna.rm: missing values should be removed or notuse: method for computing covariances when missing values exist, including
"everything", "all.obs", "complete.obs", "na.or.complete", "pairwise.complete.obs"method: method for computing correlation coefficient, including "pearson", "kendall", "spearman"V: symmeric numeric matrix>BOD
Time demand 1 1 8.3 2 2 10.3 3 3 19.0 4 4 16.0 5 5 15.6 6 7 19.8
> attach(BOD) > var(demand)
[1] 21.44267
> head(iris,3)Sepal.Length Sepal.Width Petal.Length Petal.Width Species 1 5.1 3.5 1.4 0.2 setosa 2 4.9 3.0 1.4 0.2 setosa 3 4.7 3.2 1.3 0.2 setosa > cov(iris$Sepal.Length,iris$Petal.Length)[1] 1.274315 > var(iris$Sepal.Length,iris$Petal.Length)[1] 1.274315 > x <- iris[,c(1:4)] > var(x)Sepal.Length Sepal.Width Petal.Length Petal.Width Sepal.Length 0.6856935 -0.0424340 1.2743154 0.5162707 Sepal.Width -0.0424340 0.1899794 -0.3296564 -0.1216394 Petal.Length 1.2743154 -0.3296564 3.1162779 1.2956094 Petal.Width 0.5162707 -0.1216394 1.2956094 0.5810063
