阿三
矩阵:
> n1<-c("a","b","c","d")
> n2<-c("A","B","C")
> p<-matrix(1:12,nrow = 4,ncol = 3,byrow = T,dimnames = list(n1,n2))
> p
A B C
a 1 2 3
b 4 5 6
c 7 8 9
d 10 11 12
> p[1,2]
[1] 2
> p[2]
[1] 4
> p[5]
[1] 2
> p[3,4]
Error in p[3, 4] : subscript out of bounds
> p[2,c(2,3)]
B C
5 6
> p[3,]
A B C
7 8 9
> p[,3]
a b c d
3 6 9 12
>
3.数组
> e<-c("A","B","C","D")
> b<-array(1:16,c(2,2,4),dimnames = list(q,w,e))
> q<-c("a","b")
> w<-c("武大郎","武二郎")
> e<-c("A","B","C","D")
> b<-array(1:16,c(2,2,4),dimnames = list(q,w,e))
> b
, , A
武大郎 武二郎
a 1 3
b 2 4
, , B
武大郎 武二郎
a 5 7
b 6 8
, , C
武大郎 武二郎
a 9 11
b 10 12
, , D
武大郎 武二郎
a 13 15
b 14 16
> b[2,2,1]
[1] 4
> b[1,2,4]
[1] 15
>
数据框
数据框生成
> age<-c(22,2,33,24)
> gender<-c("male","female","male","female")
> grade<-c(88,2,2,23)
> df1<-data.frame(age,gender,grade)
> df1
age gender grade
1 22 male 88
2 2 female 2
3 33 male 2
4 24 female 23
> df1[1]
age
1 22
2 2
3 33
4 24
> df1[4,1]
[1] 24
> df1[,3]
[1] 88 2 2 23
> df1[1:3,]
age gender grade
1 22 male 88
2 2 female 2
3 33 male 2
> df1[1:3,3]
[1] 88 2 2
> df1[-1,]
age gender grade
2 2 female 2
3 33 male 2
4 24 female 23
> df1["age"]
age
1 22
2 2
3 33
4 24
> df1[c()]
data frame with 0 columns and 4 rows
> df1$gender
[1] male female male female
> a<-c(2,3,1,4,5)
> b<-matrix(1:20,nrow = 4,ncol = 5)
> age<-c(1,5)
> country<-c("Chian","India")
> c<-data.frame(age,country)
> list1<-list(a=a,b=b,c=c)
> list1[1][3]
$<NA>
NULL
> list1[3][age]
$c
age country
1 1 Chian
2 5 India
$<NA>
NULL
> list1[[1]][4]
[1] 4
> list1[[3]][2][1]
country
1 Chian
2 India
> list1[[[3]]][[2]][1]
Error: unexpected '[' in "list1[[["
> list1[[3]][2,1]
[1] 5
> list1$a
[1] 2 3 1 4 5
> list1$c
age country
1 1 Chian
2 5 India
>
总结
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