CODEWITHSUNDEEP
r
HoHoHo
HoHoHo

Reputation: 311

Create group column based on multiple "ifelse"

I need to create group column - B that corresponds to another column - A

DF
A     B
XXL   1
XXL   1
XL    2
L     3
M     4
M     4
S     5

I was trying to use multiple ifelse statement. But this didnt work as it returned the column of zeros. As well i tried to use vectorized way of ifelse which resulted the same way. Thank you for any suggestions.

Upvotes: 1

Views: 65

Answers (1)

akrun
akrun

Reputation: 887078

We can either use match or factor

 DF$B <- with(DF, match(A, unique(A)))
 DF$B
 #[1] 1 1 2 3 4 4 5

Or

 as.numeric(factor(DF$A, levels = unique(DF$A)))
 #[1] 1 1 2 3 4 4 5

Here are some other options as well

 cumsum(!duplicated(DF$A))
 #[1] 1 1 2 3 4 4 5

Or with data.table

library(data.table)
setDT(DF)[, B:= .GRP, A]

Upvotes: 2

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