On Mar 15, 2012, at 10:55 AM, capy_bara wrote:
Dear all,
I am confused about how to create an expression. I use a package
(rsbml)
which uses expressions and seems to make a difference if there is a
quote
around the expression or not.
For example, package works with expressions such as
expression(A + B)
but not with
expression("A + B")
I now have a set of math expressions represented as strings,
something like
this:
rhs_eq<- c("0", "A + B", "B * (2+C)")
and want to make expressions without quotes out of it.
I tried
lapply(lapply(rhs_eq, as.symbol), as.expression)
which only turns the double quotes into single quotes, but does not
remove
the quotes.
I also played around with as.formula, as.name, quote and enquote,
but had no
success.
Does anyone know about quotes in the expression data type?
> parse(text=rhs_eq)
expression(0, A + B, B * (2+C))
> parse(text=rhs_eq)[1]
expression(0)
> parse(text=rhs_eq)[2]
expression(A + B)
> parse(text=rhs_eq)[3]
expression(B * (2+C))
Thanks in advance,
Hannes
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