Is there a way to select every other row in a dataframe?

Question

I have a dataframe where I want to keep only the odd rows, how would I go about doing that?

Answer 1

We can use a logical index as recycling vectot to return every other row from the original dataset

df1[c(TRUE, FALSE),]

Answer 2

Another option can be testing the module across all rows like this (I have used dummy data). The %% helps you to test the module with a value. As you want odd rows you can extract the rows which module different from two (1:nrow(d)%%2!=0). The 1:nrow(d) is a sequential index to evaluate the rows. Here the code:

#Code
dnew <- d[1:nrow(d)%%2!=0,]

Output:

   col1 col2 col3 col4 col5
1     4    4    1    4    Y
3     6    3    3    2    N
5     3    3    3    3    N
7     5    5    5    2    Y
9     6    6    6    6    N
11    2    2    2    2    N
13    0    0    0    0    Y
15    6    6    6    3    N
17    9    1    9    8    N

Some data used:

#Data
d <- structure(list(col1 = c(4, 5, 6, 4, 3, 4, 5, 5, 6, 9, 2, 1, 0, 
3, 6, 7, 9), col2 = c(4, 2, 3, 4, 3, 3, 5, 6, 6, 9, 2, 1, 0, 
3, 6, 7, 1), col3 = c(1, 2, 3, 4, 3, 4, 5, 5, 6, 9, 2, 1, 0, 
3, 6, 7, 9), col4 = c(4, 5, 2, 4, 3, 4, 2, 5, 6, 5, 2, 3, 0, 
3, 3, 7, 8), col5 = structure(c(2L, 1L, 1L, 2L, 1L, 1L, 2L, 1L, 
1L, 2L, 1L, 1L, 2L, 1L, 1L, 2L, 1L), .Label = c("N", "Y"), class = "factor")), class = "data.frame", row.names = c(NA, 
-17L))