100 R functions without installing extra packages

Author

Thiyanga S. Talagala

Formatting

`format`

To format numbers or strings according to a specific format

format(12.3456789, digits = 2)

[1] "12"

format(12.3456789, nsmall = 2)

[1] "12.34568"

format(1.5:5.5, trim = TRUE)

[1] "1.5" "2.5" "3.5" "4.5" "5.5"

df <- data.frame(id=c(1.1, 2.22, 3.333), letter=c("aaa", "bb", "c"))
df

     id letter
1 1.100    aaa
2 2.220     bb
3 3.333      c

format(df, justify = "left")

     id letter
1 1.100    aaa
2 2.220    bb 
3 3.333    c

`hexmode`

Print integers in hexmode

values <- 10:100
as.hexmode(values)

 [1] "0a" "0b" "0c" "0d" "0e" "0f" "10" "11" "12" "13" "14" "15" "16" "17" "18"
[16] "19" "1a" "1b" "1c" "1d" "1e" "1f" "20" "21" "22" "23" "24" "25" "26" "27"
[31] "28" "29" "2a" "2b" "2c" "2d" "2e" "2f" "30" "31" "32" "33" "34" "35" "36"
[46] "37" "38" "39" "3a" "3b" "3c" "3d" "3e" "3f" "40" "41" "42" "43" "44" "45"
[61] "46" "47" "48" "49" "4a" "4b" "4c" "4d" "4e" "4f" "50" "51" "52" "53" "54"
[76] "55" "56" "57" "58" "59" "5a" "5b" "5c" "5d" "5e" "5f" "60" "61" "62" "63"
[91] "64"

`tolower`

Convert upper case letters to lower case

words <- c("ABC", "cde", "Fgh")
tolower(words)

[1] "abc" "cde" "fgh"

`toupper`

Convert lower case letters to upper case

words <- c("ABC", "cde", "Fgh")
toupper(words)

[1] "ABC" "CDE" "FGH"

Common functions

`append`

x: the vector the values are to be appended to

values: values to be included in the modified vectors

after: a subscript (index), after which the values are to be appended

x1 <- seq(10, 50, by=10)
x2 <- 1:3
append(x1, values = x2, after = 3)

[1] 10 20 30  1  2  3 40 50

Matrix

mat <- matrix(1:9, nrow =3)

`det`

Calucate the determinant of a square matrix

base::det(mat)

[1] 0

`lower.tri/ upper.tri`

Check whether the elements belong to lower or upper triangle of a matrix

base::lower.tri(mat)

      [,1]  [,2]  [,3]
[1,] FALSE FALSE FALSE
[2,]  TRUE FALSE FALSE
[3,]  TRUE  TRUE FALSE

base::upper.tri(mat)

      [,1]  [,2]  [,3]
[1,] FALSE  TRUE  TRUE
[2,] FALSE FALSE  TRUE
[3,] FALSE FALSE FALSE

`apply`

apply(mat, 2, mean)

[1] 2 5 8

apply(mat, 2, max)

[1] 3 6 9

apply(mat, 1, max)

[1] 7 8 9

Statistical functions

`table`

Create a frequency table for a vector

table(mtcars$cyl)


 4  6  8 
11  7 14

`IQR`

IQR(mtcars$mpg)

[1] 7.375

`rank`

x <- c(1, 1, 2, 3, 10, 1, 100)
rank(x)

[1] 2 2 4 5 6 2 7

Graphics

`boxplot`

boxplot(mpg ~ cyl, data = mtcars, xlab = "Quantity of Cylinders",  
        ylab = "Miles Per Gallon", main = "Boxplot")

boxplot(mpg ~ cyl, data = mtcars,   
        xlab = "Quantity of Cylinders",  
        ylab = "Miles Per Gallon",   
        main = "Boxplot Example",  
        notch = TRUE,   
        varwidth = TRUE,   
        col = c("green","yellow","red"),  
        names = c("High","Medium","Low")  
)

Warning in (function (z, notch = FALSE, width = NULL, varwidth = FALSE, : some
notches went outside hinges ('box'): maybe set notch=FALSE

`curve`

curve (5*x+4 , -2 , 2 , ylab='y')
curve (x^2 - 2 , add = TRUE , col = "red" , ylab = 'y ')

curve (5*x^2 - 2, ylab = 'y ')

expr <- cos
curve(expr ,-2*pi, 2*pi,  ylab='cos(x)', xlab='x')

`stem`

stem(mtcars$mpg)


  The decimal point is at the |

  10 | 44
  12 | 3
  14 | 3702258
  16 | 438
  18 | 17227
  20 | 00445
  22 | 88
  24 | 4
  26 | 03
  28 | 
  30 | 44
  32 | 49

`barplot`

freq.table <- table(mtcars$gear)
barplot(freq.table, main = "Frequency by number of gears", xlab = "Number of Gears", ylab="Count", col="purple")

twoway.table <- table(mtcars$cyl, mtcars$gear)
barplot(twoway.table,
        main = "Composition of the sample by gears and cyllinders", 
        xlab = "Number of Gears",
        ylab= "Count", 
        col = rainbow(3), 
        legend = rownames(twoway.table))

Other

`sample`

x = a vector, from which to choose the sample

n = number of items to choose from

replace = should sampling be with replacement?

size = size of the sample

prob = vector of probability weights for obtaining the elements of the vector being sampled

data <- 1:10
sample(data)

 [1]  4 10  3  6  7  1  9  5  8  2

sample(data, size = 5)

[1] 2 6 9 4 7

sample(data, size = 5, replace = TRUE)

[1]  5 10  4  9  2

sample(data, size = 5, replace = FALSE)

[1] 4 3 9 8 6