How to Create a Single Dummy Variable with conditions in multiple columns?

Question

I am trying to efficiently create a binary dummy variables (1/0) in my data set based on whether or not one or more of 7 variables (col9-15) in the data set take on a specif

Answer 1

apply to the rescue :)

# this sample data frame is pre-loaded
mtcars

# test whether any of the values in the
# 2nd - 5th columns of mtcars equal four..

# save the result into a new vector..
indicator.col <- 
    apply( 
        mtcars[ , 2:5 ] , 
        1 ,
        FUN = function( x ) max( x == 4 ) 
    )

# ..that quickly binds onto mtcars
# and bind it with the original mtcars
mtcars2 <- cbind( mtcars , indicator.col )

# look at your result
mtcars2