Cộng đồng Hỏi & Đáp của Inflearn

> member

     name sex    occup age

1    john   M reporter  40

2    jeny   F  painter  24

3 rachael   F   runner  16

4     tom   M   singer  56

> age[1]

[1] 40

> name[3]

[1] "rachael"

> member[1]

     name

1    john

2    jeny

3 rachael

4     tom

> member[,1]

[1] john    jeny    rachael tom    

Levels: jeny john rachael tom

> member[1,]

  name sex    occup age

1 john   M reporter  40

> member[1]

     name

1    john

2    jeny

3 rachael

4     tom

> member$name

[1] john    jeny    rachael tom    

Levels: jeny john rachael tom

> member$sex

[1] M F F M

Levels: F M

> member[2,4]

[1] 24

> member

     name sex    occup age

1    john   M reporter  40

2    jeny   F  painter  24

3 rachael   F   runner  16

4     tom   M   singer  56

> member[2,4]

[1] 24

> member[2,3]

[1] painter

Levels: painter reporter runner singer

> member[2,3] <- 'doctor'

경고메시지(들): 

In `[<-.factor`(`*tmp*`, iseq, value = "doctor") :

  invalid factor level, NA generated

> member[2,3] <- 'doctor'

경고메시지(들): 

In `[<-.factor`(`*tmp*`, iseq, value = "doctor") :

  invalid factor level, NA generated

> member

     name sex    occup age

1    john   M reporter  40

2    jeny   F     <NA>  24

3 rachael   F   runner  16

4     tom   M   singer  56

> member[2,3]

[1] <NA>

Levels: painter reporter runner singer

> member[2,3] <- "doctor"

경고메시지(들): 

In `[<-.factor`(`*tmp*`, iseq, value = "doctor") :

  invalid factor level, NA generated

> member[2,3]

[1] <NA>

Levels: painter reporter runner singer

> member

     name sex    occup age

1    john   M reporter  40

2    jeny   F     <NA>  24

3 rachael   F   runner  16

4     tom   M   singer  56

> member[2,3] <- 'doctor'

경고메시지(들):