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rsymbols

object, variable, and symbols in R

I'm confused regarding the definition of [symbol]1. In the following example, my understanding is that h is a variable and an object, hs is the name or symbol of h, but why hs is '12' and not h?

h=12
is.symbol(h) # FALSE
hs=as.symbol(h)
is.symbol(hs) # TRUE
hs # `12`
eval(hs) # Error in eval(hs) : object '12' not found
Solution

  • it's because as.name (identical to as.symbol) converts the value stored in h to a symbol, it doesn't act on the name h itself. (Which is already a name, so why are we coercing to a name...?)

    I think you're looking for something closer to the functionality of substitute():

    h <- 12

# Converts the value stored in h to a symbol
hs1 <- as.name(h)
str(hs1) # symbol 12

eval(hs1) # Error in eval(hs1) : object '12' not found

hs2 <- substitute(h)
str(hs2) # symbol h

eval(hs2) # 12