4 R basic exercises

> print('hello') # Initial programming 
[1] "hello"
> getwd()# Get work path 
[1] "C:/RStudio/project"
> a=c(1,99,Inf,-3.58,-Inf)
> a#a vector 
[1]  1.00 99.00   Inf -3.58  -Inf
> b=c(-1L,-9L,1L,25L) #b vector 
> b
[1] -1 -9  1 25
> class(b)#b type 
[1] "integer"
> c=(-100):0#c vector 
> c
  [1] -100  -99  -98  -97  -96  -95  -94  -93  -92  -91  -90  -89  -88  -87  -86  -85  -84  -83  -82  -81  -80  -79  -78  -77  -76  -75
 [27]  -74  -73  -72  -71  -70  -69  -68  -67  -66  -65  -64  -63  -62  -61  -60  -59  -58  -57  -56  -55  -54  -53  -52  -51  -50  -49
 [53]  -48  -47  -46  -45  -44  -43  -42  -41  -40  -39  -38  -37  -36  -35  -34  -33  -32  -31  -30  -29  -28  -27  -26  -25  -24  -23
 [79]  -22  -21  -20  -19  -18  -17  -16  -15  -14  -13  -12  -11  -10   -9   -8   -7   -6   -5   -4   -3   -2   -1    0
> complex(15)# The plural 
 [1] 0+0i 0+0i 0+0i 0+0i 0+0i 0+0i 0+0i 0+0i 0+0i 0+0i 0+0i 0+0i 0+0i 0+0i 0+0i
> d=as.character(complex(15))# Coercive transformation 
> d
 [1] "0+0i" "0+0i" "0+0i" "0+0i" "0+0i" "0+0i" "0+0i" "0+0i" "0+0i" "0+0i" "0+0i" "0+0i" "0+0i" "0+0i" "0+0i"
> class(d)
[1] "character"
> list(a=1:3,b=(T:F),c("a","b"))# list 
$a
[1] 1 2 3

$b
[1] 1 0

[[3]]
[1] "a" "b"

> list(a=1:3,b=list(b1=2:4,b2="a"))# List nesting 
$a
[1] 1 2 3

$b
$b$b1
[1] 2 3 4

$b$b2
[1] "a"


> args(matrix)# Describe functions 
function (data = NA, nrow = 1, ncol = 1, byrow = FALSE, dimnames = NULL) 
NULL
> matrix(1:6,2,3)# Matrix default column arrangement 
     [,1] [,2] [,3]
[1,]    1    3    5
[2,]    2    4    6
> matrix(1:6,2,3,byrow = T,dimnames=list(c("x1","x2"),c("a","b","c")))# Name the matrix 
   a b c
x1 1 2 3
x2 4 5 6
> matrix(1,2,3)
     [,1] [,2] [,3]
[1,]    1    1    1
[2,]    1    1    1
> matrix(NA,2,3)# Fill the matrix 
     [,1] [,2] [,3]
[1,]   NA   NA   NA
[2,]   NA   NA   NA
> x=matrix(NA,2,3)# Matrix assignment 
> dim(x)
[1] 2 3
> z=1:6
> as.matrix(z)
     [,1]
[1,]    1
[2,]    2
[3,]    3
[4,]    4
[5,]    5
[6,]    6
> as.numeric(z)
[1] 1 2 3 4 5 6
> as.matrix(z)# Vector to matrix 
     [,1]
[1,]    1
[2,]    2
[3,]    3
[4,]    4
[5,]    5
[6,]    6
> as.numeric(z)# Matrix to value 
[1] 1 2 3 4 5 6
> y=7:12
> rbind(z,y)# Row merge vector 
  [,1] [,2] [,3] [,4] [,5] [,6]
z    1    2    3    4    5    6
y    7    8    9   10   11   12
> cbind(z,y)# The column merge vector is a matrix 
     z  y
[1,] 1  7
[2,] 2  8
[3,] 3  9
[4,] 4 10
[5,] 5 11
[6,] 6 12
> args(array)
function (data = NA, dim = length(data), dimnames = NULL) 
NULL
> array(1:12,dim=c(2,3,2))# Create a list of 
, , 1

     [,1] [,2] [,3]
[1,]    1    3    5
[2,]    2    4    6

, , 2

     [,1] [,2] [,3]
[1,]    7    9   11
[2,]    8   10   12

> array(1:12,dim=c(2,3,2),dimnames=list(c("x1","x2"),c("x3","x4","x5"),c("x6","x7")))
, , x6

   x3 x4 x5
x1  1  3  5
x2  2  4  6

, , x7

   x3 x4 x5
x1  7  9 11
x2  8 10 12

> x=data.frame(id=1:3,age=c(12,13,12),name=c("li","han","lao"))# Data frame 
> x            
  id age name
1  1  12   li
2  2  13  han
3  3  12  lao
> colnames(x)      # Data frame column name 
[1] "id"   "age"  "name"
> nrow(x)# Row name 
[1] 3
> nrow(x)# Row number 
[1] 3
> ncol(x)# Number of columns 
[1] 3
> l=list(a=c(1,3,2),b=c(F,T,F))# list 
> l
$a
[1] 1 3 2

$b
[1] FALSE  TRUE FALSE

> a=matrix(1:8,2,4)# matrix 
> rbind(1:4,5:8)# Matrix merging 
     [,1] [,2] [,3] [,4]
[1,]    1    2    3    4
[2,]    5    6    7    8
> b=array(1:8,dim = c(2,2,2),dimnames = list(1:2,3:4,5:6))# Create array 
> b
, , 5

  3 4
1 1 3
2 2 4

, , 6

  3 4
1 5 7
2 6 8

> c=data.frame(ID=1:3,math=c(80,78,90))# Create list box 
> list(list=l,Matrix=a,Array=b,Datafram=c)# Compound list 
$list
$list$a
[1] 1 3 2

$list$b
[1] FALSE  TRUE FALSE


$Matrix
     [,1] [,2] [,3] [,4]
[1,]    1    3    5    7
[2,]    2    4    6    8

$Array
, , 5

  3 4
1 1 3
2 2 4

, , 6

  3 4
1 5 7
2 6 8


$Datafram
  ID math
1  1   80
2  2   78
3  3   90

> factor(c("y","y","n","n"))# Categorical data factor 
[1] y y n n
Levels: n y
> factor(c(" Primary school "," Junior high school "," high school "," Primary school "),order=T,levels=c(" Primary school "," Junior high school "," high school "))# Factor sorting 
[1]  Primary school   Junior high school   high school   Primary school 
Levels:  Primary school  <  Junior high school  <  high school 
> args(gl)
function (n, k, length = n * k, labels = seq_len(n), ordered = FALSE) 
NULL
> gl(3,4)
 [1] 1 1 1 1 2 2 2 2 3 3 3 3
Levels: 1 2 3
> gl(3,4)#1-3, loop 4 Time 
 [1] 1 1 1 1 2 2 2 2 3 3 3 3
Levels: 1 2 3
> gl(2,3,12,labels=c(" male "," Woman "),order=T)# label 
 [1]  male   male   male   Woman   Woman   Woman   male   male   male   Woman   Woman   Woman 
Levels:  male  <  Woman 
> x=c(1,2,NA,NaN,3)
> is.numeric(x)
[1] TRUE
> is.na(x)
[1] FALSE FALSE  TRUE  TRUE FALSE
> is.nan(x)#NA Include NAN,NAN yes NA True subset 
[1] FALSE FALSE FALSE  TRUE FALSE
> x=1:3
> names(x)
NULL
> names(x)=c("a","b","c")# Vector naming 
> x
a b c 
1 2 3 
> x=list(1:3,c(T,F))
> x
[[1]]
[1] 1 2 3

[[2]]
[1]  TRUE FALSE

> names(x)=c("aa","bb")
> x
$aa
[1] 1 2 3

$bb
[1]  TRUE FALSE

> names(x)=c("cc","dd")# List naming 
> x
$cc
[1] 1 2 3

$dd
[1]  TRUE FALSE

> x=matrix(NA,2,3)
> x
     [,1] [,2] [,3]
[1,]   NA   NA   NA
[2,]   NA   NA   NA
> dimnames(x)=list(c("a","b"),c("x","y","z"))# Matrix naming 
> x
   x  y  z
a NA NA NA
b NA NA NA
> x=data.frame(id=1:3,math=89:91)
> x
  id math
1  1   89
2  2   90
3  3   91
> rownames(x)=c("x1","x2","x3")# Data frame row name 
> x
   id math
x1  1   89
x2  2   90
x3  3   91
> colnames(x)=c("ID","MATH")# Data frame column name 
> x
   ID MATH
x1  1   89
x2  2   90
x3  3   91
> names(x)
[1] "ID"   "MATH"
> names(x)# Name 
[1] "ID"   "MATH"
> x=factor(c(" Primary school "," Junior high school "," high school "," Primary school "," high school "),order=T,levels=c(" Primary school "," Junior high school "," high school "))
> x
[1]  Primary school   Junior high school   high school   Primary school   high school 
Levels:  Primary school  <  Junior high school  <  high school 
> gl(3,3,90,labels = c(" Primary school "," Junior high school "," high school "),order=T) 
 [1]  Primary school   Primary school   Primary school   Junior high school   Junior high school   Junior high school   high school   high school   high school   Primary school   Primary school   Primary school   Junior high school   Junior high school   Junior high school   high school   high school   high school   Primary school   Primary school   Primary school   Junior high school   Junior high school   Junior high school   high school   high school 
[27]  high school   Primary school   Primary school   Primary school   Junior high school   Junior high school   Junior high school   high school   high school   high school   Primary school   Primary school   Primary school   Junior high school   Junior high school   Junior high school   high school   high school   high school   Primary school   Primary school   Primary school   Junior high school   Junior high school   Junior high school   high school 
[53]  high school   high school   Primary school   Primary school   Primary school   Junior high school   Junior high school   Junior high school   high school   high school   high school   Primary school   Primary school   Primary school   Junior high school   Junior high school   Junior high school   high school   high school   high school   Primary school   Primary school   Primary school   Junior high school   Junior high school   Junior high school 
[79]  high school   high school   high school   Primary school   Primary school   Primary school   Junior high school   Junior high school   Junior high school   high school   high school   high school 
Levels:  Primary school  <  Junior high school  <  high school 
> z=c(0:3)
> z
[1] 0 1 2 3
> names(z)=c("a","b","c","d")
> z
a b c d 
0 1 2 3 
> z=matrix(NA,2,2)
> z
     [,1] [,2]
[1,]   NA   NA
[2,]   NA   NA
> dimnames(z)=list(c("a","b"),c("c","d"))
> z
   c  d
a NA NA
b NA NA
> x=data.frame(x=1:3,y=2:4)
> x
  x y
1 1 2
2 2 3
3 3 4
> colnames(x)=c("y","z")
> x
  y z
1 1 2
2 2 3
3 3 4
> rownames(x)=c("a","b","c")
> x
  y z
a 1 2
b 2 3
c 3 4
> x=data.frame(id=1:3,math=89:91)
> x
  id math
1  1   89
2  2   90
3  3   91
> fix(x)# It's not used in general fix Modify the data frame , Poor reusability 
> ```