Create an ID variable based on a row sequence

Asked Feb 27 '18 at 14:24

Active Feb 27 '18 at 14:34

Viewed 128 times

I have this sequence of data and I want to create an ID every 3 rows:

x <- c ("info","x1","y1","z1","x2","y2","z2")
df  <- read.csv(text = x , strip.white = TRUE)

The actual strings doesn't have any logical information that I could create an ID column using mutate + ifelse + grepl . I want to create a new column with a sequential number every 3 rows:

edited Feb 27 '18 at 14:34

Ronak Shah

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asked Feb 27 '18 at 14:24

jvqp

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`data.frame(df, id = ceiling(1:nrow(df)/3))` – d.b Feb 27 '18 at 14:27
Heaps of alternatives here: [Split a vector into chunks in R](https://stackoverflow.com/questions/3318333/split-a-vector-into-chunks-in-r) (just skip the `split` step...). E.g. the top-voted answer is the same as @d.b's suggestion. – Henrik Feb 27 '18 at 14:30
Also, `df$id <- rep(1:(nrow(df)/3), each = 3)` – Ronak Shah Feb 27 '18 at 14:31
`dplyr::mutate(df, ceiling(row_number() / 3))` – Julien Navarre Feb 27 '18 at 14:32
`(sequence(nrow(df))-1) %/% 3`. – A5C1D2H2I1M1N2O1R2T1 Feb 27 '18 at 14:38
I just answered the question you just deleted. Let me know if you still want the information. You may find it useful. – piRSquared Feb 27 '20 at 19:26
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In a nutshell, this is what it is `wrd = ['is', 'foo']; pat = fr'\b{"|".join(wrd)}\b'; dfc.col1.str.replace(pat, 'X')` – piRSquared Feb 27 '20 at 19:26

Create an ID variable based on a row sequence

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