Matrix

Matrix

x<-c(5,2,3,3,9,1)
m<-matrix(x,3,2);m

##      [,1] [,2]
## [1,]    5    3
## [2,]    2    9
## [3,]    3    1

Naming a matrix

rownames(m)<-c("row1","row2","row3");m

##      [,1] [,2]
## row1    5    3
## row2    2    9
## row3    3    1

colnames(m)<-c("col1","col2");m

##      col1 col2
## row1    5    3
## row2    2    9
## row3    3    1

rbind() and cbind()

rbind(1:3,1:3)

##      [,1] [,2] [,3]
## [1,]    1    2    3
## [2,]    1    2    3

cbind(1:3,1:3)

##      [,1] [,2]
## [1,]    1    1
## [2,]    2    2
## [3,]    3    3

inverse,transpose,determinant function

y<-c(9,1,0,6,3,2,10,24,8)
A<-matrix(y,3,3);A

##      [,1] [,2] [,3]
## [1,]    9    6   10
## [2,]    1    3   24
## [3,]    0    2    8

solve(A)#inverse of A

##              [,1]        [,2]        [,3]
## [1,]  0.098360656  0.11475410 -0.46721311
## [2,]  0.032786885 -0.29508197  0.84426230
## [3,] -0.008196721  0.07377049 -0.08606557

t(A)#Transpose of A

##      [,1] [,2] [,3]
## [1,]    9    1    0
## [2,]    6    3    2
## [3,]   10   24    8

det(A)#determinant of A

## [1] -244

Array

z<-c(9,10,14,19,2,5)
array(z,c(3,2))

##      [,1] [,2]
## [1,]    9   19
## [2,]   10    2
## [3,]   14    5

array(1:20,c(4,5))

##      [,1] [,2] [,3] [,4] [,5]
## [1,]    1    5    9   13   17
## [2,]    2    6   10   14   18
## [3,]    3    7   11   15   19
## [4,]    4    8   12   16   20

array(c(1:3,3:1),c(3,2))

##      [,1] [,2]
## [1,]    1    3
## [2,]    2    2
## [3,]    3    1