如何将分类变量二分为具有 1 和 0 的新变量但保持 NA？

Question

I am trying to create a new variable within my data frame to encapsulate questions with two categorical answers. I would like to be able to convert these to 1s and 0s.

I've been using the ifelse() function but I feel like it inherently wants to convert NA values into 0s in my case. Adding the na.rm=TRUE argument onto the end gives me an error.

data$Knowledge=ifelse(data$Variable=="Yes",1,0, na.rm=TRUE)

Error in ifelse(data$Sabe.qué.trata.la.Ley.No.26378..Convención.sobre.los.Derechos.de.las.personas.con.discapacidad..sobre.las.personas.Sordas.o.hipoacúsicas. ==: unused argument (na.rm = TRUE)

Answer 1

ifelse() doesn't have an na.rm argument (in any case, you don't want to remove NA values, you want to pass them on in the result). A solution with explicit logic: nested ifelse

x <- c("Yes","No",NA)
ifelse(is.na(x),NA,ifelse(x=="Yes",1,0))

A more efficient solution based on coercion of logical values to integers ( TRUE -> 1, FALSE -> 0, NA -> NA )

as.integer(x=="Yes")