R中数值向量中的空数值

Question

I want to create a numeric vector in R with a placeholder. Just like in a chracter vector like:

characterVec <- c("a", "b", "", "d")

This gives me a characterVec vector with a length of 4.

How can I create a numeric vector with a length of 4, but still has one empty value? For example, I would like to know what do I put into the question mark in the following vector.

numericVec <- c(1, 2, ?, 4)

Answer 1

If I'm understanding your question properly, you can use a named vector to create a data dictionary linking letters to corresponding numbers:

# data dictionary
dat <- 1:26
names(dat) <- letters

then map dictionary onto your vector

characterVec <- c("a", "b", "", "d")
numVec <- dat[characterVec]

gives

   a    b <NA>    d 
   1    2   NA    4 

You can remove the vector names with unname() :

numVec <- unname(dat[characterVec])