see below.
On Fri, Apr 13, 2012 at 8:50 PM, Kjetil Halvorsen
<kjetilbrinchmannhalvor...@gmail.com> wrote:
I am experimenting with rSymPy, and it seems to work nice.
However, I dislike the need to wrap all sympy expressions within
quotes, it leads to ugly calls like
library(rSymPy)
Var("x,y,z")
sympy("(x+y)**2")
and so on.
Inspired by the function cq from mvbutiles package:
library(mvbutils)
cq
function (...)
{
as.character(sapply(as.list(match.call(expand.dots = TRUE))[-1],
as.character))
}
<bytecode: 0x7fca88443f78>
<environment: namespace:mvbutils>
I tried to write
sympyq
function(...) {
arg<- as.character(match.call(expand.dots=TRUE)[-1])
thiscall<- as.call(list(as.name("sympy"), arg))
print( thiscall ) # for debugging
eval(thiscall, parent.frame() )
}
Some examples:
(After doing
Var("x,y,z") )
sympyq(4+4)
sympy("4 + 4")
[1] "8"
sympyq(3*x+4*y+89*z-6*x)
sympy("3 * x + 4 * y + 89 * z - 6 * x")
[1] "-3*x + 4*y + 89*z"
But then:
sympyq( (x+y)**2 )
sympy("(x + y)^2")
Error in .jcall("RJavaTools", "Ljava/lang/Object;", "invokeMethod", cl, :
Traceback (most recent call last):
File "<string>", line 1, in<module>
TypeError: unsupported operand type(s) for ^: 'Add' and 'int'
Note that R has changed the syntax **2 to ^2, which sympy does not
seem to like!
Any ideas for avoiding this, or more generally, better ideas for
achieving what I am trying to do?
Kjetil
Ok, I am trying now with
sympyq
function(...) {
arg<- as.character(match.call(expand.dots=TRUE)[-1])
arg<- gsub('^', x=arg, replacement='**', fixed=TRUE)
thiscall<- as.call(list(as.name("sympy"), arg))
print( thiscall )
eval(thiscall, parent.frame() )
}
which gives:
sympyq( (x+y)**2 )
sympy("(x + y)**2")
[1] "(x + y)**2"
sympyq ( sin(pi) )
sympy("sin(pi)")
[1] "0"
sympyq( limit(sin(x)/x, x, 0) )
sympy("limit(sin(x)/x, x, 0)")
[1] "1"
sympyq( diff(sin(2*x), x, 2) )
sympy("diff(sin(2 * x), x, 2)")
[1] "-4*sin(2*x)"
so seems to work, but then, tyhe following I do not understand:
sympyq( ((x+y)**2).expand() )
Error: unexpected symbol in "sympyq( ((x+y)**2).expand"
