1) 숫자 표현
#5 + 6의2승
> 5 + 6^2
[1] 41
> #log10 10
> log10(10)
[1] 1
> #logee
> log(exp(exp(1)))
[1] 2.718282
> #e의 2승
> exp(2)
[1] 7.389056
2) 파일 읽어오기
#workshop2.txt 읽어오기
> path <- "C:\\Users\\user\\Desktop\\data\\workshop2.txt"
> f <- read.table(path, header=T, encoding="UTF-8", stringsAsFactors = F)
> f
name weight height
1 Lee 93 1.72
2 Kim 82 1.81
3 Kueon 80 1.70
4 Kang 67 1.69
5 Choi 72 1.83
6 Keo 69 1.76
3) 테이블 정보로 BMI 구하기
#BMI구하기 (weight / height^2)
> y
name weight height
1 Lee 93 1.72
2 Kim 82 1.81
3 Kueon 80 1.70
4 Kang 67 1.69
5 Choi 72 1.83
6 Keo 69 1.76
7 Han 62 1.73
> y1 <- y[,-1]
> y1
weight height
1 93 1.72
2 82 1.81
3 80 1.70
4 67 1.69
5 72 1.83
6 69 1.76
7 62 1.73
> y2 <- y1[,-2]
> y2
[1] 93 82 80 67 72 69 62
> y3 <- y1[,-1]
> y3
[1] 1.72 1.81 1.70 1.69 1.83 1.76 1.73
> y4 <-(y3*y3)
> y4
[1] 2.9584 3.2761 2.8900 2.8561 3.3489 3.0976 2.9929
> BMI <- y2/y4
> BMI
[1] 31.43591 25.02976 27.68166 23.45856 21.49960 22.27531 20.71569
(* 잘 모르겠어서 y에서 열을 잘라와 y2, y3에 넣음ㅋㅋㅋㅋㅋ)
4) BMI 컬럼 추가하기
#BMI 컬럼추가하기
> y <- cbind(y, BMI)
> y
name weight height BMI
1 Lee 93 1.72 31.43591
2 Kim 82 1.81 25.02976
3 Kueon 80 1.70 27.68166
4 Kang 67 1.69 23.45856
5 Choi 72 1.83 21.49960
6 Keo 69 1.76 22.27531
7 Han 62 1.73 20.71569
5) 몸무게의 평균, 표준편차 구하기
- 평균 : mean(x)
- 표준편차 : sd(x)
#평균
> mean(y2)
[1] 75
#표준편차
> sd(y2)
[1] 10.61446
6) BMI 카테고리 만들어 컬럼 추가하기
Underweight =< 18.5
Normal weight = 18.5-24.9
Overweight =25-29.9
Obesity = BMI of 30 or greater
#BMI CATEGORIES
> x <- c()
> x
NULL
> for(s in BMI){
+ if(s <= 18.5) {
+ x <-c(x, "Underweight")
+ } else if (s <=24.9){
+ x <-c(x, "Normal weight")
+ } else if (s <=29.9){
+ x <-c(x, "Overweight")
+ } else {
+ x <-c(x, "Obesity")
+ }
+ }
> x
[1] "Obesity" "Overweight" "Overweight" "Normal weight" "Normal weight"
[6] "Normal weight" "Normal weight"#BMI CATEGORY 컬럼 추가하기
> y <- cbind(y, COMMENT = x)
> y
name weight height BMI COMMENT
1 Lee 93 1.72 31.43591 Obesity
2 Kim 82 1.81 25.02976 Overweight
3 Kueon 80 1.70 27.68166 Overweight
4 Kang 67 1.69 23.45856 Normal weight
5 Choi 72 1.83 21.49960 Normal weight
6 Keo 69 1.76 22.27531 Normal weight
7 Han 62 1.73 20.71569 Normal weight
#선생님이 하신 방법
#파일읽어오기
path <- "C:\\Users\\user\\Desktop\\data\\workshop2.txt"
> workshop2 <- read.table(path, header=T, stringsAsFactors=F)
> str(workshop2)
'data.frame': 6 obs. of 3 variables:
$ name : chr "Lee" "Kim" "Kueon" "Kang" ...
$ weight: int 93 82 80 67 72 69
$ height: num 1.72 1.81 1.7 1.69 1.83 1.76
> workshop2
name weight height
1 Lee 93 1.72
2 Kim 82 1.81
3 Kueon 80 1.70
4 Kang 67 1.69
5 Choi 72 1.83
6 Keo 69 1.76
> workshop2 <- rbind(workshop2, list("Han", 62, 1.73))
> str(workshop2)
'data.frame': 7 obs. of 3 variables:
$ name : chr "Lee" "Kim" "Kueon" "Kang" ...
$ weight: num 93 82 80 67 72 69 62
$ height: num 1.72 1.81 1.7 1.69 1.83 1.76 1.73
#BMI 구하기
BMI <- workshop2$weight / workshop2$height^2
> BMI
[1] 31.43591 25.02976 27.68166 23.45856 21.49960 22.27531 20.71569
> workshop2 <- cbind(workshop2, BMI)
> str(workshop2)
'data.frame': 7 obs. of 4 variables:
$ name : chr "Lee" "Kim" "Kueon" "Kang" ...
$ weight: num 93 82 80 67 72 69 62
$ height: num 1.72 1.81 1.7 1.69 1.83 1.76 1.73
$ BMI : num 31.4 25 27.7 23.5 21.5 ...
> workshop2
name weight height BMI
1 Lee 93 1.72 31.43591
2 Kim 82 1.81 25.02976
3 Kueon 80 1.70 27.68166
4 Kang 67 1.69 23.45856
5 Choi 72 1.83 21.49960
6 Keo 69 1.76 22.27531
7 Han 62 1.73 20.71569
#BMI카테고리 생성
> comments <- workshop2$BMI
> comments
[1] 31.43591 25.02976 27.68166 23.45856 21.49960 22.27531 20.71569
> comments[workshop2$BMI < 18.5] <- "Under"
> comments[workshop2$BMI >=18.5 & workshop2$BMI < 25] <- "Normal"
> comments[workshop2$BMI >=25 & workshop2$BMI < 30] <- "Over"
> comments[workshop2$BMI >=30] <- "Obesity"
> comments
[1] "Obesity" "Over" "Over" "Normal" "Normal" "Normal" "Normal"
workshop2 <- cbind(workshop2, comments)
> str(workshop2)
'data.frame': 7 obs. of 5 variables:
$ name : chr "Lee" "Kim" "Kueon" "Kang" ...
$ weight : num 93 82 80 67 72 69 62
$ height : num 1.72 1.81 1.7 1.69 1.83 1.76 1.73
$ BMI : num 31.4 25 27.7 23.5 21.5 ...
$ comments: Factor w/ 3 levels "Normal","Obesity",..: 2 3 3 1 1 1 1
> workshop2
name weight height BMI comments
1 Lee 93 1.72 31.43591 Obesity
2 Kim 82 1.81 25.02976 Over
3 Kueon 80 1.70 27.68166 Over
4 Kang 67 1.69 23.45856 Normal
5 Choi 72 1.83 21.49960 Normal
6 Keo 69 1.76 22.27531 Normal
7 Han 62 1.73 20.71569 Normal
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