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UCBAdmissions[,1,]

##           Dept
## Admit        A   B   C   D   E   F
##   Admitted 512 353 120 138  53  22
##   Rejected 313 207 205 279 138 351

UCBAdmissions[,1,1]

## Admitted Rejected 
##      512      313

UCBAdmissions[1,1,]

##   A   B   C   D   E   F 
## 512 353 120 138  53  22

dim(UCBAdmissions)

## [1] 2 2 6

str(UCBAdmissions)

##  '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" ...

dimnames(UCBAdmissions)

## $Admit
## [1] "Admitted" "Rejected"
## 
## $Gender
## [1] "Male"   "Female"
## 
## $Dept
## [1] "A" "B" "C" "D" "E" "F"

UCBAdmissions[,1,] 這個指令會叫出屬於男性的所有變項資料(Admit, Dept)

UCBAdmissions[1,1,] 這個指令會叫出Admitted men的資料(各個Dept的人數)

UCBAdmissions[,1,1] 這個指令會叫出屬於Dept A的男性的資料(是否Admit)