CODEWITHSUNDEEP
rsequence
Rb99
Rb99

Reputation: 71

How can I create a sequence that repeats the value when TRUE is in the same position in a seperate vector in R?

For example, how can I take what's in x1 and turn it into x2 in an efficient way? I'm working with a large data set so for loops are not preferable.

      x1 x2
1  FALSE  1
2  FALSE  2
3   TRUE  3
4   TRUE  3
5  FALSE  4
6  FALSE  5
7  FALSE  6
8   TRUE  7
9   TRUE  7
10 FALSE  8
11 FALSE  9
12 FALSE 10
13 FALSE 11
14 FALSE 12
15 FALSE 13
16 FALSE 14
17 FALSE 15
18 FALSE 16
19  TRUE 17
20  TRUE 17
21 FALSE 18
22 FALSE 19
23 FALSE 20
24 FALSE 21

Upvotes: 0

Views: 34

Answers (1)

Ronak Shah
Ronak Shah

Reputation: 388982

One base R way would be to increment value by 1 when there is FALSE or the value changes from the previous value.

with(df, cumsum(!x1 | c(TRUE, diff(x1) != 0)))
#[1]  1  2  3  3  4  5  6  7  7  8  9 10 11 12 13 14 15 16 17 17 18 19 20 21

data

df <- structure(list(x1 = c(FALSE, FALSE, TRUE, TRUE, FALSE, FALSE, 
FALSE, TRUE, TRUE, FALSE, FALSE, FALSE, FALSE, FALSE, FALSE, 
FALSE, FALSE, FALSE, TRUE, TRUE, FALSE, FALSE, FALSE, FALSE)), row.names = c(NA, 
-24L), class = "data.frame")

Upvotes: 1

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