R学习之quote与substitute的不同

substitute returns the parse tree for the (unevaluated) expression expr, substituting any variables bound in env.

quote simply returns its argument. The argument is not evaluated and can be any R expression.

Here’s an example that may help you to easily see the difference between quote() and substitute(), in one of the settings (processing function arguments) where substitute() is most commonly used:

f <- function(argX) {
   list(quote(argX), substitute(argX), argX)
}

suppliedArgX <- 100
f(argX = suppliedArgX)
# [[1]]
# argX
# 
# [[2]]
# suppliedArgX
# 
# [[3]]
# [1] 100