R - Create a repetitive list from a smaller length vector to fit into dataframe

Question

How to create a repetitive list (field) from a smaller length vector to fit into dataframe? I want to add the vector as a column by repetiting the vector.

Answer 1

Hi Nithin,

rep() is used to replicate a vector, so you can use it for your problem.

Syntax: rep(vector,replication_number).

Ex: rep(c(1:5),5)

To add the replicated vector to a data frame, you can give replication_number as [number of rows]/[size of vector]

For suppose if the data frame consists of 23 rows and vector has 5 elements,  then use code as 

length.out is used to mention the size of the new vector after replication. It ignores is the size of replicated is more than data frame size.

> z = data.frame(x=1:23,y=21:43)
> z
    x  y
1   1 21
2   2 22
3   3 23
4   4 24
5   5 25
6   6 26
7   7 27
8   8 28
9   9 29
10 10 30
11 11 31
12 12 32
13 13 33
14 14 34
15 15 35
16 16 36
17 17 37
18 18 38
19 19 39
20 20 40
21 21 41
22 22 42
23 23 43
> z$vec = rep(c(1:5),5,length.out = nrow(z))
> z
    x  y vec
1   1 21   1
2   2 22   2
3   3 23   3
4   4 24   4
5   5 25   5
6   6 26   1
7   7 27   2
8   8 28   3
9   9 29   4
10 10 30   5
11 11 31   1
12 12 32   2
13 13 33   3
14 14 34   4
15 15 35   5
16 16 36   1
17 17 37   2
18 18 38   3
19 19 39   4
20 20 40   5
21 21 41   1
22 22 42   2
23 23 43   3