> ?wilcox.test
> x <- c(1.83,  0.50,  1.62,  2.48, 1.68, 1.88, 1.55, 3.06, 1.30)
> y <- c(0.878, 0.647, 0.598, 2.05, 1.06, 1.29, 1.06, 3.14, 1.29)
> wilcox.test(x, y, paired = TRUE, alternative = "greater")

	Wilcoxon signed rank test

data:  x and y 
V = 40, p-value = 0.01953
alternative hypothesis: true location shift is greater than 0 

> wilcox.test(x, y, paired = TRUE)

	Wilcoxon signed rank test

data:  x and y 
V = 40, p-value = 0.03906
alternative hypothesis: true location shift is not equal to 0 

> wilcox.test(x, y)

	Wilcoxon rank sum test with continuity
	correction

data:  x and y 
W = 58, p-value = 0.1329
alternative hypothesis: true location shift is not equal to 0 

Warning message:
In wilcox.test.default(x, y) : cannot compute exact p-value with ties

----------------------------------------------------------------------
> v1 <- rnorm(100)
> v2 <- rnorm(100, mean=3)
> v3 <- rnorm(100, mean=3, sd=5)
> boxplot(v1, v2, v3)
> par(mfrow=c(3,1))
> hist(v1)
> hist(v2)
> hist(v3)


----------------------------------------------------------------------
> x <- c(NA, 3, 4, 5, NA)
> y <- c(1, 2, NA, 3, 4)
> !is.na(x & y)
[1] FALSE  TRUE FALSE  TRUE FALSE
> 1+NA
[1] NA
> !is.na(x + y)
[1] FALSE  TRUE FALSE  TRUE FALSE

> !is.na(x) & !is.na(y)
[1] FALSE  TRUE FALSE  TRUE FALSE

> mean
function (x, ...) 
UseMethod("mean")
<environment: namespace:base>

> sum
function (..., na.rm = FALSE)  .Primitive("sum")
> c
function (..., recursive = FALSE)  .Primitive("c")

> f <- function(x) x^2
> f(2)
[1] 4

> m <- function(a, b) {
+     if (a < b)
+         b
+     else
+         a
+ }
> m(1, 2)
[1] 2

> s <- function(v) {
+     sum <- 0
+     for (x in v)
+         sum <- sum + x
+ }
> s(1:3)
> x <- s(1:3)
> x
NULL
> fix(s)
> s
function(v) {
    sum <- 0
    for (x in v)
        sum <- sum + x
    return(sum)
}
> s(1:3)
[1] 6
> fix(s)
> s
function(v) {
    sum <- 0
    for (x in v)
        sum <- sum + x
    return(sum)
}
> sum
function (..., na.rm = FALSE)  .Primitive("sum")
> inc <- function(x, by=1) x + by
> inc
function(x, by=1) x + by
> inc(1)
[1] 2
> inc(1, by=10)
[1] 11
> inc(by=10, 1)
[1] 11
> plot(1:10)
> 
> plot(1:10)
> plot(1:10, main="my title")
> function(x) x^2
function(x) x^2
> sum
function (..., na.rm = FALSE)  .Primitive("sum")
> c
function (..., recursive = FALSE)  .Primitive("c")
> c(1, 2, 3, 34)
[1]  1  2  3 34
> c(1, 2, 3, 34, 4, 4)
[1]  1  2  3 34  4  4
> ?plot
> ls()
[1] "f"   "inc" "m"   "s"   "v"   "v2"  "v3"  "x"  
[9] "y"  
> function(x) x^2
function(x) x^2
> f
function(x) x^2
> x <- 1
> f(2)
[1] 4
> f <- function(x) {
+    x <- 2
+ }
> x
[1] 1
> f(1)
> x
[1] 1
> f <- function(x) {
+    x <<- 2
+ }
> f()
> x
[1] 2
> x <- 1
> f <- function(y) x + y
> f(1)
[1] 2
>