#vectors
vec.a = c(2,3,4,5,6,7,8,9,10,11,12,13,14,15)
vec.a = c(2:15)
vec.a = as.numeric(c("-.01"," 2.5 ","C"))
vec.a = seq(2,15,by=1)
vec.a = c(a, b, c, d)
#matrices
vec1 = c(2,3,4,5,6,7,8,9,10,11,12,13,14,15)
vec2 = c(as.numeric(22:35))
vec3 = seq(42,55,by=1)
vecb = c("aa", "bb", "cc", "dd", "ee", "", "gg",
"hh","ii", "jj", "kk", "ll","mm","nn")
matr1 = cbind(vec1, vec2, vec3)
matr2 = rbind(vec1, vec2, vec3)
matr3 = cbind(vec1, vec2, vec3, vecb)
matr4 = matrix(vecb,7,2)
matr5=matrix(vec1,ncol=2,byrow=TRUE)
#if statement
x=c(2,7,1,8,9)
med=function(x) {odd=length(x)%% 2
if (odd==0)
{med=(sort(x)[length(x)/2]+sort(x)[1+length(x)/2])/2}
else med=sort(x)[ceiling(length(x)/2)]
med
}
med(x)
m
#ifelse statement
y=log(c(3,0.5,2,4))
ifelse(y<0,NA,y)
#for loop factorial
x=4
fac=function(x){
f=1
if (x<2) {f=1}
else {for (i in 2:x) f=f*i
     }
return (f)
}
fac(4)
#for loops
for (i in 1:2) print(i)
for (i in (1:4)-2) print(i)
library(MASS)
data(phones)
for(var in names(phones)) print(var)
for(func in c(sin,cos)) print(func(pi))
#leaving the loop:stop
a = 1:10
b = NULL
for (i in seq(along=a))
{ if (a[i]<5 || a[i]>8) { b = c(b,a[i]) } else {
stop("values need to be <5") } }
b
#breaking the loop:break
rm(b)
a = 1:10
b = NULL
for (i in seq(along=a))
{ if (a[i]<5 || a[i]>8) { b = c(b,a[i])} else
{break("values of a need to be <5")}}
b
#breaking the loop:next
rm(b)
a = 1:10
b = NULL
for (i in seq(along=a)) { if (a[i]<5 || a[i]>8) { b =
c(b,a[i])} else { next}}
b
#other loops:while
x=4
f=1
t=x
while (t > 1){
f=f*t
t=t-1 }
f
#other loops:repeat
x=4
f=1
t=x
repeat {
if (t < 2) break
f=f*t
t=t-1 }
f
#apply
matrix = matrix(c(1:10, 11:20), nrow = 10, ncol = 2)
apply(matrix, 1, mean)
apply(matrix, 2, mean)
apply(matrix, 1:2, function(x) x*2)