Create new sequential column if value in another column is non-unique

Question

I have two columns x and y, I am trying to create a new sequenced column z if the value in one of the columns is non-unique. e.g.

x <- c("1", "1", "1", "1", "2", "2", "2", "3", "3", "3", "4", "4", "5", "6", "6", "6")
y <- c("Y", "Y", "Y", "Y", "N", "N", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "N", "Y", "Y")
df <- data.frame(x, y)

What I would like to get is the following:

#    x     y         z
#
#    1     Y         1
#    1     Y         2
#    1     Y         3
#    1     Y         4
#    2     N         1
#    2     N         2
#    2     Y         3
#    3     Y         1
#    3     Y         2
#    3     Y         3
#    4     Y         1
#    4     Y         2
#    5     Y         1
#    6     N         1
#    6     Y         2
#    6     Y         3

Does this answer your question? [Running count based on field in R](https://stackoverflow.com/questions/31259932/running-count-based-on-field-in-r) — QHarr, Jun 06 '22 at 16:07
No that question is different. Darren thank you, I will include your answer as accepted answer. — zerberus, Jun 06 '22 at 16:16
I was able to solve your question with the top answer from my linked one. — QHarr, Jun 06 '22 at 19:17
@QHarr yes, I understand what you mean, I guess your link the first row wasn't ordered, hence I didn't understand, but Darren's makes more sense to me. Thanks — zerberus, Jun 07 '22 at 14:41
@DarrenTsai how can I create an interval in the sequences, e.g. if I wanted 2,4,6 instead of 1,2,3. — zerberus, Jun 13 '22 at 16:46
Maybe `ave(df$x, df$x, FUN = \(x) seq(2, by = 2, len = length(x)))` — Darren Tsai, Jun 13 '22 at 17:05

score 1 · Accepted Answer · answered Jun 06 '22 at 16:23

y <- c("Y", "Y", "Y", "Y", "N", "N", "Y", "Y", "Y", "Y", "Y", "Y", "Y", "N", "Y", "Y")
df <- data.frame(x, y) 

df$z <- ave(df$x, df$x, FUN = seq_along)

gives

Create new sequential column if value in another column is non-unique

1 Answers1