Archive for February 2007
My first snippets with R:
> x <- c (1, 4, 3, 2, 3, 3, 6, 5, 6, 2, 5, 1, 1); > mean (x); [1] 3.230769 > mean (x) - sum (x) / length (x); [1] 0 > var (x); [1] 3.358974 > var (x) - mean ((x - mean (x))^2); [1] 0.2583826 > var (x) - sum ((x - mean (x))^2) / (length (x) - 1); [1] 0 > stddev <- sqrt (var (x)); > stddev; [1] 1.832750 > var (x) - cov (x, x); [1] 0 > y <- c (1, 3, 3, 1, 4, 3, 7, 6, 6, 6, 2, 2, 3); > cov (x, y); [1] 2.346154 > cov(x,y)-sum((x-mean(x))*(y-mean(y)))/(length(x)-1); [1] 0 > length (y) - length (x); [1] 0 > cor (x, y); [1] 0.633002 > cor (x, y) - cov (x, y) / sqrt (var (x)) / sqrt (var (y)); [1] 0 >
