rep()函数:重复
rep(x,...)
rep.int(x,times)
rep_len(x,length.out)
·x:一个向量(vector),一个因子(factor),一个POSIXct或POSIXlt或Date对象(object)...
·...:更多其他的选项,可能有如下的:
·times:必为非负整数,负数或NA是错误的。每一个向量重复的次数。
·length.out:必为非负整数,缺省或NA是错误的。输出向量期待的输出长度。
·each:必为非负整数,值为1或NA是错误的。每一个元素重复each次。
times:同...
length.out:非负整数,输出向量期待的输出长度。
例1:
> rep(1:4,2) [1] 1 2 3 4 1 2 3 4 > rep(1:4,each=2) [1] 1 1 2 2 3 3 4 4 > rep(1:4,c(2,2,2,2)) [1] 1 1 2 2 3 3 4 4 > rep(1:4,each=2,len=4) [1] 1 1 2 2 > rep(1:4,each=2,len=10) [1] 1 1 2 2 3 3 4 4 1 1 > rep(1:4,each=2,times=3) [1] 1 1 2 2 3 3 4 4 1 1 2 2 3 3 4 4 1 1 2 2 3 3 4 4
例2:
> rep(1,40*(1-.8)) [1] 1 1 1 1 1 1 1 > 40*(1-.8) [1] 8 > rep(1,40*(1-.8)+1e-7) [1] 1 1 1 1 1 1 1 1 > 40*(1-.8)+1e-7 [1] 8
例3:
> #replicate a list > fred<-list(happy=1:10,name="squash") > rep(fred,5) $happy [1] 1 2 3 4 5 6 7 8 9 10 $name [1] "squash" $happy [1] 1 2 3 4 5 6 7 8 9 10 $name [1] "squash" $happy [1] 1 2 3 4 5 6 7 8 9 10 $name [1] "squash" $happy [1] 1 2 3 4 5 6 7 8 9 10 $name [1] "squash" $happy [1] 1 2 3 4 5 6 7 8 9 10 $name [1] "squash"
例4:
> x<-.leap.seconds[1:3] > rep(x,2) [1] "1972-07-01 08:00:00 CST" [2] "1973-01-01 08:00:00 CST" [3] "1974-01-01 08:00:00 CST" [4] "1972-07-01 08:00:00 CST" [5] "1973-01-01 08:00:00 CST" [6] "1974-01-01 08:00:00 CST" > rep(as.POSIXlt(x),rep(2,3)) [1] "1972-07-01 08:00:00 CST" [2] "1972-07-01 08:00:00 CST" [3] "1973-01-01 08:00:00 CST" [4] "1973-01-01 08:00:00 CST" [5] "1974-01-01 08:00:00 CST" [6] "1974-01-01 08:00:00 CST" > rep(as.POSIXct(x),rep(2,3)) [1] "1972-07-01 08:00:00 CST" [2] "1972-07-01 08:00:00 CST" [3] "1973-01-01 08:00:00 CST" [4] "1973-01-01 08:00:00 CST" [5] "1974-01-01 08:00:00 CST" [6] "1974-01-01 08:00:00 CST" > rep(as.Date(x),rep(2,3)) [1] "1972-07-01" "1972-07-01" "1973-01-01" [4] "1973-01-01" "1974-01-01" "1974-01-01"
例5:
> x<-factor(LETTERS[1:4]);names(x)<-letters[1:4] > x a b c d A B C D Levels: A B C D > rep(x,2) a b c d a b c d A B C D A B C D Levels: A B C D > rep(x,each=2) a a b b c c d d A A B B C C D D Levels: A B C D > rep.int(x,2) [1] A B C D A B C D Levels: A B C D > rep_len(x,10) [1] A B C D A B C D A B Levels: A B C D
来源:https://www.cnblogs.com/wangshenwen/p/3235866.html