check if a value exists group by id in R

Question

I want to define a variable new_var by the following criteria:

For each id, if exist reference=1, then new_var=1; else new_var=0, for exemple:

id      reference 
A            0   
A            1     
B            0   
B            0

Create a new_var, the table looks like this:

id      reference     new_var
A            0          1
A            1          1
B            0          0
B            0          0

I only know that I can use the statement case when in SAS, but in R how to do this?

`df$new_var <- ave(df$reference, df$id, FUN = any)` – Ronak Shah Feb 27 '17 at 09:04 — Ronak Shah, Feb 27 '17 at 09:04
@RonakShah Thanks, that works – velvetrock Feb 27 '17 at 09:07 — velvetrock, Feb 27 '17 at 09:07

score 2 · Accepted Answer · answered Feb 27 '17 at 09:12

2

Here is a base R option with transform

transform(df1, new_var = as.integer(id %in% id[reference>0]))
#   id reference new_var
#1  A         0       1
#2  A         1       1
#3  B         0       0
#4  B         0       0

answered Feb 27 '17 at 09:12

akrun

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check if a value exists group by id in R

1 Answers1