create dummy indicator for each variable in a data frame with specific values

Question

I have 115 variables in my data frame, and I need to create a dummy variable for each variable that has negative value or values of 999. The dummy indicator will take a value of 1 if the original x value is <0 or 999 and 0 otherwise. For example for the following data frame

at<-c(1,-9,-1,999)
Bc<-c(1,-2,999,0)
df<-data.frame(at,Bc)

I want to have an output dataframe with the following format:

at        Bc    I.at    I.Bc
 1         1      0       0
-9        -2      1       1
-1        999     1       1
999        0      1       0

Answer 1

You can use a base R solution like this:

transform(df,I=ifelse(df<0|df==999,1,0))
   at  Bc I.at I.Bc
1   1   1    0    0
2  -9  -2    1    1
3  -1 999    1    1
4 999   0    1    0