thuc hanh

bài thực hành số 1

thao tác trên dataset

data(trees)
d <- trees 
str(d)

## 'data.frame':    31 obs. of  3 variables:
##  $ Girth : num  8.3 8.6 8.8 10.5 10.7 10.8 11 11 11.1 11.2 ...
##  $ Height: num  70 65 63 72 81 83 66 75 80 75 ...
##  $ Volume: num  10.3 10.3 10.2 16.4 18.8 19.7 15.6 18.2 22.6 19.9 ...

names(d) <- c('G','h','v') 

tới đây đã xong vài việc

head(trees)

##   Girth Height Volume
## 1   8.3     70   10.3
## 2   8.6     65   10.3
## 3   8.8     63   10.2
## 4  10.5     72   16.4
## 5  10.7     81   18.8
## 6  10.8     83   19.7

vol <- d$v 
vol15 <- vol[vol>15 & vol <50]
voll <- d[d$v >15 |d$h >60,]
vol[3] 

## [1] 10.2

vol

##  [1] 10.3 10.3 10.2 16.4 18.8 19.7 15.6 18.2 22.6 19.9 24.2 21.0 21.4 21.3 19.1
## [16] 22.2 33.8 27.4 25.7 24.9 34.5 31.7 36.3 38.3 42.6 55.4 55.7 58.3 51.5 51.0
## [31] 77.0

vol15

##  [1] 16.4 18.8 19.7 15.6 18.2 22.6 19.9 24.2 21.0 21.4 21.3 19.1 22.2 33.8 27.4
## [16] 25.7 24.9 34.5 31.7 36.3 38.3 42.6

min(vol)

## [1] 10.2

max(vol)

## [1] 77

d$logv <- log(d$v)
d$logh <- log(d$h)
d$sinh <- sin(d$h)
d$sqrtv <- sqrt(d$v)
d$Tong <- d$G + d$h + d$v
cut(vol,4)

##  [1] (10.1,26.9] (10.1,26.9] (10.1,26.9] (10.1,26.9] (10.1,26.9] (10.1,26.9]
##  [7] (10.1,26.9] (10.1,26.9] (10.1,26.9] (10.1,26.9] (10.1,26.9] (10.1,26.9]
## [13] (10.1,26.9] (10.1,26.9] (10.1,26.9] (10.1,26.9] (26.9,43.6] (26.9,43.6]
## [19] (10.1,26.9] (10.1,26.9] (26.9,43.6] (26.9,43.6] (26.9,43.6] (26.9,43.6]
## [25] (26.9,43.6] (43.6,60.3] (43.6,60.3] (43.6,60.3] (43.6,60.3] (43.6,60.3]
## [31] (60.3,77.1]
## Levels: (10.1,26.9] (26.9,43.6] (43.6,60.3] (60.3,77.1]

table(cut(vol,4))

## 
## (10.1,26.9] (26.9,43.6] (43.6,60.3] (60.3,77.1] 
##          18           7           5           1