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rsurvey

Combining Survey Items in R/ Recoding NAs

I have two lists (from a multi-wave survey) that look like this: 

X1 X2
1  NA
NA  2
NA  NA

How can I easily combine this into a third item, where the third column always takes the non-NA value of column X1 or X2, and codes NA when both values are NA?

Solution

  • Combining Gavin's use of within and Prasad's use of ifelse gives us a simpler answer.

    within(df, x3 <- ifelse(is.na(x1), x2, x1))

    Multiple ifelse calls are not needed - when both values are NA, you can just take one of the values directly.