#(1)

average_sepal_length <- mean(iris$Sepal.Length)
da1 <- subset(iris, Sepal.Length > average_sepal_length)
nrow(da1)
## [1] 70
da2 <- iris[!(iris$Sepal.Length > average_sepal_length), ]
nrow(da2)
## [1] 80
#(2)

library(ggplot2)
plot1 <- ggplot(iris, aes(Sepal.Length, Petal.Length, color = Species)) + geom_point() +labs(title = "Relationship between Sepal.Length and Petal.Length",x = "Sepal.Length", y = "Petal.Length") +theme_bw()
plot1

#(3)
plot2 <- ggplot(iris, aes(Sepal.Width, Petal.Width, color = Species)) + geom_point() +labs(title = "Relationship between Sepal.Width and Petal.Width",x = "Sepal.Width", y = "Petal.Width") + theme_bw()
plot2

#(4)
d <- cbind(iris[, 1:2], iris[, 3:5])
d
##     Sepal.Length Sepal.Width Petal.Length Petal.Width    Species
## 1            5.1         3.5          1.4         0.2     setosa
## 2            4.9         3.0          1.4         0.2     setosa
## 3            4.7         3.2          1.3         0.2     setosa
## 4            4.6         3.1          1.5         0.2     setosa
## 5            5.0         3.6          1.4         0.2     setosa
## 6            5.4         3.9          1.7         0.4     setosa
## 7            4.6         3.4          1.4         0.3     setosa
## 8            5.0         3.4          1.5         0.2     setosa
## 9            4.4         2.9          1.4         0.2     setosa
## 10           4.9         3.1          1.5         0.1     setosa
## 11           5.4         3.7          1.5         0.2     setosa
## 12           4.8         3.4          1.6         0.2     setosa
## 13           4.8         3.0          1.4         0.1     setosa
## 14           4.3         3.0          1.1         0.1     setosa
## 15           5.8         4.0          1.2         0.2     setosa
## 16           5.7         4.4          1.5         0.4     setosa
## 17           5.4         3.9          1.3         0.4     setosa
## 18           5.1         3.5          1.4         0.3     setosa
## 19           5.7         3.8          1.7         0.3     setosa
## 20           5.1         3.8          1.5         0.3     setosa
## 21           5.4         3.4          1.7         0.2     setosa
## 22           5.1         3.7          1.5         0.4     setosa
## 23           4.6         3.6          1.0         0.2     setosa
## 24           5.1         3.3          1.7         0.5     setosa
## 25           4.8         3.4          1.9         0.2     setosa
## 26           5.0         3.0          1.6         0.2     setosa
## 27           5.0         3.4          1.6         0.4     setosa
## 28           5.2         3.5          1.5         0.2     setosa
## 29           5.2         3.4          1.4         0.2     setosa
## 30           4.7         3.2          1.6         0.2     setosa
## 31           4.8         3.1          1.6         0.2     setosa
## 32           5.4         3.4          1.5         0.4     setosa
## 33           5.2         4.1          1.5         0.1     setosa
## 34           5.5         4.2          1.4         0.2     setosa
## 35           4.9         3.1          1.5         0.2     setosa
## 36           5.0         3.2          1.2         0.2     setosa
## 37           5.5         3.5          1.3         0.2     setosa
## 38           4.9         3.6          1.4         0.1     setosa
## 39           4.4         3.0          1.3         0.2     setosa
## 40           5.1         3.4          1.5         0.2     setosa
## 41           5.0         3.5          1.3         0.3     setosa
## 42           4.5         2.3          1.3         0.3     setosa
## 43           4.4         3.2          1.3         0.2     setosa
## 44           5.0         3.5          1.6         0.6     setosa
## 45           5.1         3.8          1.9         0.4     setosa
## 46           4.8         3.0          1.4         0.3     setosa
## 47           5.1         3.8          1.6         0.2     setosa
## 48           4.6         3.2          1.4         0.2     setosa
## 49           5.3         3.7          1.5         0.2     setosa
## 50           5.0         3.3          1.4         0.2     setosa
## 51           7.0         3.2          4.7         1.4 versicolor
## 52           6.4         3.2          4.5         1.5 versicolor
## 53           6.9         3.1          4.9         1.5 versicolor
## 54           5.5         2.3          4.0         1.3 versicolor
## 55           6.5         2.8          4.6         1.5 versicolor
## 56           5.7         2.8          4.5         1.3 versicolor
## 57           6.3         3.3          4.7         1.6 versicolor
## 58           4.9         2.4          3.3         1.0 versicolor
## 59           6.6         2.9          4.6         1.3 versicolor
## 60           5.2         2.7          3.9         1.4 versicolor
## 61           5.0         2.0          3.5         1.0 versicolor
## 62           5.9         3.0          4.2         1.5 versicolor
## 63           6.0         2.2          4.0         1.0 versicolor
## 64           6.1         2.9          4.7         1.4 versicolor
## 65           5.6         2.9          3.6         1.3 versicolor
## 66           6.7         3.1          4.4         1.4 versicolor
## 67           5.6         3.0          4.5         1.5 versicolor
## 68           5.8         2.7          4.1         1.0 versicolor
## 69           6.2         2.2          4.5         1.5 versicolor
## 70           5.6         2.5          3.9         1.1 versicolor
## 71           5.9         3.2          4.8         1.8 versicolor
## 72           6.1         2.8          4.0         1.3 versicolor
## 73           6.3         2.5          4.9         1.5 versicolor
## 74           6.1         2.8          4.7         1.2 versicolor
## 75           6.4         2.9          4.3         1.3 versicolor
## 76           6.6         3.0          4.4         1.4 versicolor
## 77           6.8         2.8          4.8         1.4 versicolor
## 78           6.7         3.0          5.0         1.7 versicolor
## 79           6.0         2.9          4.5         1.5 versicolor
## 80           5.7         2.6          3.5         1.0 versicolor
## 81           5.5         2.4          3.8         1.1 versicolor
## 82           5.5         2.4          3.7         1.0 versicolor
## 83           5.8         2.7          3.9         1.2 versicolor
## 84           6.0         2.7          5.1         1.6 versicolor
## 85           5.4         3.0          4.5         1.5 versicolor
## 86           6.0         3.4          4.5         1.6 versicolor
## 87           6.7         3.1          4.7         1.5 versicolor
## 88           6.3         2.3          4.4         1.3 versicolor
## 89           5.6         3.0          4.1         1.3 versicolor
## 90           5.5         2.5          4.0         1.3 versicolor
## 91           5.5         2.6          4.4         1.2 versicolor
## 92           6.1         3.0          4.6         1.4 versicolor
## 93           5.8         2.6          4.0         1.2 versicolor
## 94           5.0         2.3          3.3         1.0 versicolor
## 95           5.6         2.7          4.2         1.3 versicolor
## 96           5.7         3.0          4.2         1.2 versicolor
## 97           5.7         2.9          4.2         1.3 versicolor
## 98           6.2         2.9          4.3         1.3 versicolor
## 99           5.1         2.5          3.0         1.1 versicolor
## 100          5.7         2.8          4.1         1.3 versicolor
## 101          6.3         3.3          6.0         2.5  virginica
## 102          5.8         2.7          5.1         1.9  virginica
## 103          7.1         3.0          5.9         2.1  virginica
## 104          6.3         2.9          5.6         1.8  virginica
## 105          6.5         3.0          5.8         2.2  virginica
## 106          7.6         3.0          6.6         2.1  virginica
## 107          4.9         2.5          4.5         1.7  virginica
## 108          7.3         2.9          6.3         1.8  virginica
## 109          6.7         2.5          5.8         1.8  virginica
## 110          7.2         3.6          6.1         2.5  virginica
## 111          6.5         3.2          5.1         2.0  virginica
## 112          6.4         2.7          5.3         1.9  virginica
## 113          6.8         3.0          5.5         2.1  virginica
## 114          5.7         2.5          5.0         2.0  virginica
## 115          5.8         2.8          5.1         2.4  virginica
## 116          6.4         3.2          5.3         2.3  virginica
## 117          6.5         3.0          5.5         1.8  virginica
## 118          7.7         3.8          6.7         2.2  virginica
## 119          7.7         2.6          6.9         2.3  virginica
## 120          6.0         2.2          5.0         1.5  virginica
## 121          6.9         3.2          5.7         2.3  virginica
## 122          5.6         2.8          4.9         2.0  virginica
## 123          7.7         2.8          6.7         2.0  virginica
## 124          6.3         2.7          4.9         1.8  virginica
## 125          6.7         3.3          5.7         2.1  virginica
## 126          7.2         3.2          6.0         1.8  virginica
## 127          6.2         2.8          4.8         1.8  virginica
## 128          6.1         3.0          4.9         1.8  virginica
## 129          6.4         2.8          5.6         2.1  virginica
## 130          7.2         3.0          5.8         1.6  virginica
## 131          7.4         2.8          6.1         1.9  virginica
## 132          7.9         3.8          6.4         2.0  virginica
## 133          6.4         2.8          5.6         2.2  virginica
## 134          6.3         2.8          5.1         1.5  virginica
## 135          6.1         2.6          5.6         1.4  virginica
## 136          7.7         3.0          6.1         2.3  virginica
## 137          6.3         3.4          5.6         2.4  virginica
## 138          6.4         3.1          5.5         1.8  virginica
## 139          6.0         3.0          4.8         1.8  virginica
## 140          6.9         3.1          5.4         2.1  virginica
## 141          6.7         3.1          5.6         2.4  virginica
## 142          6.9         3.1          5.1         2.3  virginica
## 143          5.8         2.7          5.1         1.9  virginica
## 144          6.8         3.2          5.9         2.3  virginica
## 145          6.7         3.3          5.7         2.5  virginica
## 146          6.7         3.0          5.2         2.3  virginica
## 147          6.3         2.5          5.0         1.9  virginica
## 148          6.5         3.0          5.2         2.0  virginica
## 149          6.2         3.4          5.4         2.3  virginica
## 150          5.9         3.0          5.1         1.8  virginica
d1 <- cbind(iris[, 1], iris[, 2])
d1
##        [,1] [,2]
##   [1,]  5.1  3.5
##   [2,]  4.9  3.0
##   [3,]  4.7  3.2
##   [4,]  4.6  3.1
##   [5,]  5.0  3.6
##   [6,]  5.4  3.9
##   [7,]  4.6  3.4
##   [8,]  5.0  3.4
##   [9,]  4.4  2.9
##  [10,]  4.9  3.1
##  [11,]  5.4  3.7
##  [12,]  4.8  3.4
##  [13,]  4.8  3.0
##  [14,]  4.3  3.0
##  [15,]  5.8  4.0
##  [16,]  5.7  4.4
##  [17,]  5.4  3.9
##  [18,]  5.1  3.5
##  [19,]  5.7  3.8
##  [20,]  5.1  3.8
##  [21,]  5.4  3.4
##  [22,]  5.1  3.7
##  [23,]  4.6  3.6
##  [24,]  5.1  3.3
##  [25,]  4.8  3.4
##  [26,]  5.0  3.0
##  [27,]  5.0  3.4
##  [28,]  5.2  3.5
##  [29,]  5.2  3.4
##  [30,]  4.7  3.2
##  [31,]  4.8  3.1
##  [32,]  5.4  3.4
##  [33,]  5.2  4.1
##  [34,]  5.5  4.2
##  [35,]  4.9  3.1
##  [36,]  5.0  3.2
##  [37,]  5.5  3.5
##  [38,]  4.9  3.6
##  [39,]  4.4  3.0
##  [40,]  5.1  3.4
##  [41,]  5.0  3.5
##  [42,]  4.5  2.3
##  [43,]  4.4  3.2
##  [44,]  5.0  3.5
##  [45,]  5.1  3.8
##  [46,]  4.8  3.0
##  [47,]  5.1  3.8
##  [48,]  4.6  3.2
##  [49,]  5.3  3.7
##  [50,]  5.0  3.3
##  [51,]  7.0  3.2
##  [52,]  6.4  3.2
##  [53,]  6.9  3.1
##  [54,]  5.5  2.3
##  [55,]  6.5  2.8
##  [56,]  5.7  2.8
##  [57,]  6.3  3.3
##  [58,]  4.9  2.4
##  [59,]  6.6  2.9
##  [60,]  5.2  2.7
##  [61,]  5.0  2.0
##  [62,]  5.9  3.0
##  [63,]  6.0  2.2
##  [64,]  6.1  2.9
##  [65,]  5.6  2.9
##  [66,]  6.7  3.1
##  [67,]  5.6  3.0
##  [68,]  5.8  2.7
##  [69,]  6.2  2.2
##  [70,]  5.6  2.5
##  [71,]  5.9  3.2
##  [72,]  6.1  2.8
##  [73,]  6.3  2.5
##  [74,]  6.1  2.8
##  [75,]  6.4  2.9
##  [76,]  6.6  3.0
##  [77,]  6.8  2.8
##  [78,]  6.7  3.0
##  [79,]  6.0  2.9
##  [80,]  5.7  2.6
##  [81,]  5.5  2.4
##  [82,]  5.5  2.4
##  [83,]  5.8  2.7
##  [84,]  6.0  2.7
##  [85,]  5.4  3.0
##  [86,]  6.0  3.4
##  [87,]  6.7  3.1
##  [88,]  6.3  2.3
##  [89,]  5.6  3.0
##  [90,]  5.5  2.5
##  [91,]  5.5  2.6
##  [92,]  6.1  3.0
##  [93,]  5.8  2.6
##  [94,]  5.0  2.3
##  [95,]  5.6  2.7
##  [96,]  5.7  3.0
##  [97,]  5.7  2.9
##  [98,]  6.2  2.9
##  [99,]  5.1  2.5
## [100,]  5.7  2.8
## [101,]  6.3  3.3
## [102,]  5.8  2.7
## [103,]  7.1  3.0
## [104,]  6.3  2.9
## [105,]  6.5  3.0
## [106,]  7.6  3.0
## [107,]  4.9  2.5
## [108,]  7.3  2.9
## [109,]  6.7  2.5
## [110,]  7.2  3.6
## [111,]  6.5  3.2
## [112,]  6.4  2.7
## [113,]  6.8  3.0
## [114,]  5.7  2.5
## [115,]  5.8  2.8
## [116,]  6.4  3.2
## [117,]  6.5  3.0
## [118,]  7.7  3.8
## [119,]  7.7  2.6
## [120,]  6.0  2.2
## [121,]  6.9  3.2
## [122,]  5.6  2.8
## [123,]  7.7  2.8
## [124,]  6.3  2.7
## [125,]  6.7  3.3
## [126,]  7.2  3.2
## [127,]  6.2  2.8
## [128,]  6.1  3.0
## [129,]  6.4  2.8
## [130,]  7.2  3.0
## [131,]  7.4  2.8
## [132,]  7.9  3.8
## [133,]  6.4  2.8
## [134,]  6.3  2.8
## [135,]  6.1  2.6
## [136,]  7.7  3.0
## [137,]  6.3  3.4
## [138,]  6.4  3.1
## [139,]  6.0  3.0
## [140,]  6.9  3.1
## [141,]  6.7  3.1
## [142,]  6.9  3.1
## [143,]  5.8  2.7
## [144,]  6.8  3.2
## [145,]  6.7  3.3
## [146,]  6.7  3.0
## [147,]  6.3  2.5
## [148,]  6.5  3.0
## [149,]  6.2  3.4
## [150,]  5.9  3.0
d2 <- subset(iris, Species == "setosa")
d3 <- subset(iris, Species == "versicolor")
r1 <- rbind(d2, d3)
r1
##     Sepal.Length Sepal.Width Petal.Length Petal.Width    Species
## 1            5.1         3.5          1.4         0.2     setosa
## 2            4.9         3.0          1.4         0.2     setosa
## 3            4.7         3.2          1.3         0.2     setosa
## 4            4.6         3.1          1.5         0.2     setosa
## 5            5.0         3.6          1.4         0.2     setosa
## 6            5.4         3.9          1.7         0.4     setosa
## 7            4.6         3.4          1.4         0.3     setosa
## 8            5.0         3.4          1.5         0.2     setosa
## 9            4.4         2.9          1.4         0.2     setosa
## 10           4.9         3.1          1.5         0.1     setosa
## 11           5.4         3.7          1.5         0.2     setosa
## 12           4.8         3.4          1.6         0.2     setosa
## 13           4.8         3.0          1.4         0.1     setosa
## 14           4.3         3.0          1.1         0.1     setosa
## 15           5.8         4.0          1.2         0.2     setosa
## 16           5.7         4.4          1.5         0.4     setosa
## 17           5.4         3.9          1.3         0.4     setosa
## 18           5.1         3.5          1.4         0.3     setosa
## 19           5.7         3.8          1.7         0.3     setosa
## 20           5.1         3.8          1.5         0.3     setosa
## 21           5.4         3.4          1.7         0.2     setosa
## 22           5.1         3.7          1.5         0.4     setosa
## 23           4.6         3.6          1.0         0.2     setosa
## 24           5.1         3.3          1.7         0.5     setosa
## 25           4.8         3.4          1.9         0.2     setosa
## 26           5.0         3.0          1.6         0.2     setosa
## 27           5.0         3.4          1.6         0.4     setosa
## 28           5.2         3.5          1.5         0.2     setosa
## 29           5.2         3.4          1.4         0.2     setosa
## 30           4.7         3.2          1.6         0.2     setosa
## 31           4.8         3.1          1.6         0.2     setosa
## 32           5.4         3.4          1.5         0.4     setosa
## 33           5.2         4.1          1.5         0.1     setosa
## 34           5.5         4.2          1.4         0.2     setosa
## 35           4.9         3.1          1.5         0.2     setosa
## 36           5.0         3.2          1.2         0.2     setosa
## 37           5.5         3.5          1.3         0.2     setosa
## 38           4.9         3.6          1.4         0.1     setosa
## 39           4.4         3.0          1.3         0.2     setosa
## 40           5.1         3.4          1.5         0.2     setosa
## 41           5.0         3.5          1.3         0.3     setosa
## 42           4.5         2.3          1.3         0.3     setosa
## 43           4.4         3.2          1.3         0.2     setosa
## 44           5.0         3.5          1.6         0.6     setosa
## 45           5.1         3.8          1.9         0.4     setosa
## 46           4.8         3.0          1.4         0.3     setosa
## 47           5.1         3.8          1.6         0.2     setosa
## 48           4.6         3.2          1.4         0.2     setosa
## 49           5.3         3.7          1.5         0.2     setosa
## 50           5.0         3.3          1.4         0.2     setosa
## 51           7.0         3.2          4.7         1.4 versicolor
## 52           6.4         3.2          4.5         1.5 versicolor
## 53           6.9         3.1          4.9         1.5 versicolor
## 54           5.5         2.3          4.0         1.3 versicolor
## 55           6.5         2.8          4.6         1.5 versicolor
## 56           5.7         2.8          4.5         1.3 versicolor
## 57           6.3         3.3          4.7         1.6 versicolor
## 58           4.9         2.4          3.3         1.0 versicolor
## 59           6.6         2.9          4.6         1.3 versicolor
## 60           5.2         2.7          3.9         1.4 versicolor
## 61           5.0         2.0          3.5         1.0 versicolor
## 62           5.9         3.0          4.2         1.5 versicolor
## 63           6.0         2.2          4.0         1.0 versicolor
## 64           6.1         2.9          4.7         1.4 versicolor
## 65           5.6         2.9          3.6         1.3 versicolor
## 66           6.7         3.1          4.4         1.4 versicolor
## 67           5.6         3.0          4.5         1.5 versicolor
## 68           5.8         2.7          4.1         1.0 versicolor
## 69           6.2         2.2          4.5         1.5 versicolor
## 70           5.6         2.5          3.9         1.1 versicolor
## 71           5.9         3.2          4.8         1.8 versicolor
## 72           6.1         2.8          4.0         1.3 versicolor
## 73           6.3         2.5          4.9         1.5 versicolor
## 74           6.1         2.8          4.7         1.2 versicolor
## 75           6.4         2.9          4.3         1.3 versicolor
## 76           6.6         3.0          4.4         1.4 versicolor
## 77           6.8         2.8          4.8         1.4 versicolor
## 78           6.7         3.0          5.0         1.7 versicolor
## 79           6.0         2.9          4.5         1.5 versicolor
## 80           5.7         2.6          3.5         1.0 versicolor
## 81           5.5         2.4          3.8         1.1 versicolor
## 82           5.5         2.4          3.7         1.0 versicolor
## 83           5.8         2.7          3.9         1.2 versicolor
## 84           6.0         2.7          5.1         1.6 versicolor
## 85           5.4         3.0          4.5         1.5 versicolor
## 86           6.0         3.4          4.5         1.6 versicolor
## 87           6.7         3.1          4.7         1.5 versicolor
## 88           6.3         2.3          4.4         1.3 versicolor
## 89           5.6         3.0          4.1         1.3 versicolor
## 90           5.5         2.5          4.0         1.3 versicolor
## 91           5.5         2.6          4.4         1.2 versicolor
## 92           6.1         3.0          4.6         1.4 versicolor
## 93           5.8         2.6          4.0         1.2 versicolor
## 94           5.0         2.3          3.3         1.0 versicolor
## 95           5.6         2.7          4.2         1.3 versicolor
## 96           5.7         3.0          4.2         1.2 versicolor
## 97           5.7         2.9          4.2         1.3 versicolor
## 98           6.2         2.9          4.3         1.3 versicolor
## 99           5.1         2.5          3.0         1.1 versicolor
## 100          5.7         2.8          4.1         1.3 versicolor
d4 <- iris[1, 1:4]
d5 <- iris[1, 4:5]
r2 <- merge(d4, d5, by.x="Petal.Width", by.y="Petal.Width")
r2
##   Petal.Width Sepal.Length Sepal.Width Petal.Length Species
## 1         0.2          5.1         3.5          1.4  setosa
#(5)
apply(iris[,1:4],2,sum)
## Sepal.Length  Sepal.Width Petal.Length  Petal.Width 
##        876.5        458.6        563.7        179.9
lapply(iris[,1:4],mean)
## $Sepal.Length
## [1] 5.843333
## 
## $Sepal.Width
## [1] 3.057333
## 
## $Petal.Length
## [1] 3.758
## 
## $Petal.Width
## [1] 1.199333
tapply(iris$Sepal.Length,iris$Species,sum)
##     setosa versicolor  virginica 
##      250.3      296.8      329.4
sepallength.per.species <- aggregate(iris$Sepal.Length, by=list(iris$Species), FUN=mean)
sepallength.per.species
##      Group.1     x
## 1     setosa 5.006
## 2 versicolor 5.936
## 3  virginica 6.588