How to create a data frame in R with repeated rows by a sequence of number of times or by a fixed number of times?

There are times when duplicated rows in a data frame are required, mainly they are used to extend the data size instead of collecting the raw data. This saves our time but surely it will have some biasedness, which is not recommended. Even though it is not recommended but sometimes it becomes necessary, for example, if it is impossible to collect raw data then we can do it. If we do so then we must specify it in our analysis report. In R, we can use rep function with seq_len and nrows to create a data frame with repeated rows.

Example

Consider the below data frame df −

> x<-1:10
> y<-letters[1:10]
> df<-data.frame(x,y)

Creating a new data frame in which the rows are printed one more after original rows −

> df[rep(seq_len(nrow(df)), times = 2), ]
      x y
1     1 a
2     2 b
3     3 c
4     4 d
5     5 e
6     6 f
7     7 g
8     8 h
9     9 i
10   10 j
1.1   1 a
2.1   2 b
3.1   3 c
4.1   4 d
5.1   5 e
6.1   6 f
7.1   7 g
8.1   8 h
9. 1  9 i
10.1 10 j

Creating a new data frame in which the duplicate rows are printed one by one −

> df[rep(seq_len(nrow(df)), each = 2), ]
      x y
1     1 a
1.1   1 a
2     2 b
2.1   2 b
3     3 c
3.1   3 c
4     4 d
4.1   4 d
5     5 e
5.1   5 e
6     6 f
6.1   6 f
7     7 g
7.1   7 g
8     8 h
8.1   8 h
9     9 i
9.1   9 i
10   10 j
10.1 10 j

Repeating each row by sequence of numbers −

> df[rep(seq_len(nrow(df)), times = 1:10), ]
      x y
1     1 a
2     2 b
2.1   2 b
3 3     c
3.1   3 c
3.2   3 c
4 4     d
4.1   4 d
4.2   4 d
4.3   4 d
5 5     e
5.1   5 e
5.2   5 e
5.3   5 e
5.4   5 e
6     6 f
6.1   6 f
6.2   6 f
6.3   6 f
6.4   6 f
6.5   6 f
7     7 g
7.1   7 g
7.2   7 g
7.3   7 g
7.4   7 g
7.5   7 g
7.6   7 g
8     8 h
8.1   8 h
8.2   8 h
8.3   8 h
8.4   8 h
8.5   8 h
8.6   8 h
8.7   8 h
9     9 i
9.1   9 i
9.2   9 i
9.3   9 i
9.4   9 i
9.5   9 i
9.6   9 i
9.7   9 i
9.8   9 i
10   10 j
10.1 10 j
10.2 10 j
10.3 10 j
10.4 10 j
10.5 10 j
10.6 10 j
10.7 10 j
10.8 10 j
10.9 10 j

Nizamuddin Siddiqui

Updated on: 10-Aug-2020

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