##question3
library(MASS)
dta <- MASS::birthwt
table(birthwt$race)
##
## 1 2 3
## 96 26 67
##運用table5指令查詢為26
head(dta$race <- c("White", "Black", "Other"))
## [1] "White" "Black" "Other"
##head指令將下載的package的特定提取出來
##question4
library(datasets)
list(UCBAdmissions)
## [[1]]
## , , Dept = A
##
## Gender
## Admit Male Female
## Admitted 512 89
## Rejected 313 19
##
## , , Dept = B
##
## Gender
## Admit Male Female
## Admitted 353 17
## Rejected 207 8
##
## , , Dept = C
##
## Gender
## Admit Male Female
## Admitted 120 202
## Rejected 205 391
##
## , , Dept = D
##
## Gender
## Admit Male Female
## Admitted 138 131
## Rejected 279 244
##
## , , Dept = E
##
## Gender
## Admit Male Female
## Admitted 53 94
## Rejected 138 299
##
## , , Dept = F
##
## Gender
## Admit Male Female
## Admitted 22 24
## Rejected 351 317
dta <- datasets::UCBAdmissions
str(dta)
## 'table' num [1:2, 1:2, 1:6] 512 313 89 19 353 207 17 8 120 205 ...
## - attr(*, "dimnames")=List of 3
## ..$ Admit : chr [1:2] "Admitted" "Rejected"
## ..$ Gender: chr [1:2] "Male" "Female"
## ..$ Dept : chr [1:6] "A" "B" "C" "D" ...
##UCBAdmissions數字三列代表有三個index
dta[,1,]
## Dept
## Admit A B C D E F
## Admitted 512 353 120 138 53 22
## Rejected 313 207 205 279 138 351
dta[,1,1]
## Admitted Rejected
## 512 313
dta[1,1,]
## A B C D E F
## 512 353 120 138 53 22
##有數字為指定顯示,第一列(直),第二行(橫)
##question5
##str建構chickwts的資料
str(chickwts)
## 'data.frame': 71 obs. of 2 variables:
## $ weight: num 179 160 136 227 217 168 108 124 143 140 ...
## $ feed : Factor w/ 6 levels "casein","horsebean",..: 2 2 2 2 2 2 2 2 2 2 ...
class(chickwts)
## [1] "data.frame"
##定義chickwts的資料種類是data.frame
chickwts[,2]
## [1] horsebean horsebean horsebean horsebean horsebean horsebean horsebean
## [8] horsebean horsebean horsebean linseed linseed linseed linseed
## [15] linseed linseed linseed linseed linseed linseed linseed
## [22] linseed soybean soybean soybean soybean soybean soybean
## [29] soybean soybean soybean soybean soybean soybean soybean
## [36] soybean sunflower sunflower sunflower sunflower sunflower sunflower
## [43] sunflower sunflower sunflower sunflower sunflower sunflower meatmeal
## [50] meatmeal meatmeal meatmeal meatmeal meatmeal meatmeal meatmeal
## [57] meatmeal meatmeal meatmeal casein casein casein casein
## [64] casein casein casein casein casein casein casein
## [71] casein
## Levels: casein horsebean linseed meatmeal soybean sunflower
##以第二列內容順序呈現
chickwts["feed"]
## feed
## 1 horsebean
## 2 horsebean
## 3 horsebean
## 4 horsebean
## 5 horsebean
## 6 horsebean
## 7 horsebean
## 8 horsebean
## 9 horsebean
## 10 horsebean
## 11 linseed
## 12 linseed
## 13 linseed
## 14 linseed
## 15 linseed
## 16 linseed
## 17 linseed
## 18 linseed
## 19 linseed
## 20 linseed
## 21 linseed
## 22 linseed
## 23 soybean
## 24 soybean
## 25 soybean
## 26 soybean
## 27 soybean
## 28 soybean
## 29 soybean
## 30 soybean
## 31 soybean
## 32 soybean
## 33 soybean
## 34 soybean
## 35 soybean
## 36 soybean
## 37 sunflower
## 38 sunflower
## 39 sunflower
## 40 sunflower
## 41 sunflower
## 42 sunflower
## 43 sunflower
## 44 sunflower
## 45 sunflower
## 46 sunflower
## 47 sunflower
## 48 sunflower
## 49 meatmeal
## 50 meatmeal
## 51 meatmeal
## 52 meatmeal
## 53 meatmeal
## 54 meatmeal
## 55 meatmeal
## 56 meatmeal
## 57 meatmeal
## 58 meatmeal
## 59 meatmeal
## 60 casein
## 61 casein
## 62 casein
## 63 casein
## 64 casein
## 65 casein
## 66 casein
## 67 casein
## 68 casein
## 69 casein
## 70 casein
## 71 casein
##呈現第二列總類和個數
##question6
library(MASS)
require(MASS)
items <- ls("package:MASS")
str(items)
## chr [1:165] "abbey" "accdeaths" "addterm" "Aids2" "Animals" "anorexia" ...
##建構MASS的items
items[90+1:2]
## [1] "Melanoma" "menarche"
##指定items[90+1:2]第92個
find.package("MASS")
## [1] "C:/Program Files/R/R-3.6.3/library/MASS"