library(stringr) ulysses_lines <- “Stately, plump Buck Mulligan came from the stairhead, bearing a bowl of lather on which a mirror and a razor lay crossed.”
Ulysses_remove <- gsub(“[[:punct:]]”, ““, ulysses_lines)
ulysses_remove <- gsub(“[[:punct:]]”, ““, ulysses_lines)
ulysses_words <- str_split(ulysses_remove, ” “)[[1]]
every_third_word <- ulysses_words[seq(1, length(ulysses_words), by = 3)]
every_third_word [1] “Stately” “Mulligan” “the” [4] “a” “lather” “a”
[7] “a” “crossed”
Suppose m <- matrix(data = 1:80, nrow = 8, ncol = 10, byrow = FALSE)
Extract and assign columns to x
> x <- m[, c(2,3,6)]
> x [,1] [,2] [,3] [1,] 9 17 41 [2,] 10 18 42 [3,] 11 19 43 [4,] 12 20 44 [5,] 13 21 45 [6,] 14 22 46 [7,] 15 23 47 [8,] 16 24 48 2, 3, 6:
> x <- m[, c(2,3,6)]
> x [,1] [,2] [,3] [1,] 9 17 41 [2,] 10 18 42 [3,] 11 19 43 [4,] 12 20 44 [5,] 13 21 45 [6,] 14 22 46 [7,] 15 23 47 [8,] 16 24 48
Rows 6-8:
> x <- m[6:8,] > x [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [1,] 6 14 22 30 38 46 54 62 70 78 [2,] 7 15 23 31 39 47 55 63 71 79 [3,] 8 16 24 32 40 48 56 64 72 80
Row 2, Column 2 -> Row 6, Column 9:
> x <- m[2:6, 2:9] >
x
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [1,] 10 18 26 34 42 50 58 66
[2,] 11 19 27 35 43 51 59 67
[3,] 12 20 28 36 44 52 60 68
[4,] 13 21 29 37 45 53 61 69
[5,] 14 22 30 38 46 54 62 70
My array: > a <- array(400:1, dim = c(5, 5, 4, 4))
Returns: a[1, 1, 1, 2] [300] a[2, 3, 2, ] [1] 364 264 164 64 a[1:5, 1:5, 3, 3] [,1] [,2] [,3] [,4] [,5] [1,] 150 145 140 135 130 [2,] 149 144 139 134 129 [3,] 148 143 138 133 128 [4,] 147 142 137 132 127 [5,] 146 141 136 131 126
> Haplorhini <- list(Anthropoidea, Tarsioidea) >Catarrhini <- c(“Cercopithecidae”, “Hylobatidae”, “Hominidae”)
>Platyrrhini <- c(“Cebidae”, “Atelidae”, “Pitheciidae”)
> Anthropoidea <- list(Platyrrhini, Catarrhini)
> Tarsioidea = c(“Tarsiidae”)
> names(Haplorhini) <- list(“Anthropoidea”, “Catarrhini”)
Strepsirhini
Lemuroidea <- c(“Cheirogaleidae”, “Lepilemuridae”, “Indriidae”, “Lemuridae”, “Daubentoniidae”)
Lorisoidea <- c(“Lorisidae”, “Galagidae”)
Strepsirhini <- list(Lemuroidea, Lorisoidea)
names(Strepsirhini) <- list(“Lemuroidea”, “Lorisoidea”)
Primates names(Primates) <- list(“Haplorhini”, “Strepsirhini”)
Primates <- list(Haplorhini, Strepsirhini)
Primates
numbers <- c(3, 0, 1, 23, 1, 2, 33, 1, 1, 42, 0, 1, 41, 0, 2)
m <- matrix(numbers, nrow = 5, ncol = 3, byrow = TRUE)
m
[,1] [,2] [,3]
[1,] 3 0 1
[2,] 23 1 2
[3,] 33 1 1
[4,] 42 0 1
[5,] 41 0 2
Data Frame
numbers <- c(3, 0, 1, 23, 1, 2, 33, 1, 1, 42, 0, 1, 41, 0, 2)
df <- as.data.frame(m)
df[, 2] <- as.logical(df[, 2])
df[, 3] <- as.factor(df[, 3])
df
V1 V2 V3
1 3 FALSE 1
2 23 TRUE 2
3 33 TRUE 1
4 42 FALSE 1
5 41 FALSE 2
str(df)
‘data.frame’: 5 obs. of 3 variables:
$ V1: num 3 23 33 42 41
$ V2: logi FALSE TRUE TRUE FALSE FALSE
$ V3: Factor w/ 2 levels “1”,“2”: 1 2 1 1 2 … Edits