Aliases: expression is.expression as.expression as.expression.default
Keywords: programming dplot
### ** Examples length(ex1 <- expression(1 + 0:9)) # 1
[1] 1
ex1
expression(1 + 0:9)
eval(ex1) # 1:10
[1] 1 2 3 4 5 6 7 8 9 10
length(ex3 <- expression(u, 2, u + 0:9)) # 3
[1] 3
mode(ex3 [3]) # expression
[1] "expression"
mode(ex3[[3]]) # call
[1] "call"
## but not all components are 'call's : sapply(ex3, mode ) # name numeric call
[1] "name" "numeric" "call"
sapply(ex3, typeof) # symbol double language
[1] "symbol" "double" "language"
rm(ex3)