[R] from character string to function body?
Dear R users,
I wonder if it is possible to form a function from a character string. Here is
an example:
x=3
`-`(`+`(`^`(x,3),`^`(x,2)),1) # Here is my function evaluated.
[1] 35
V=list(`-`,(,`+`,(,`^`,(,x,,,3,),,,`^`,(,x,,,2,),),,,1,))
# Here I construct the string, it could be vector as well?
S=noquote(paste(V,collapse=))
S
[1] `-`(`+`(`^`(x,3),`^`(x,2)),1) # Here is the same as a character string.
Now I'd like to create a function using this string, something like this, but
of course, this doesn't work:
S=as.expression(S)
F1-function(x){S}
Is there some way to do this?
Cheers,
Atte Tenkanen
University of Turku, Finland
__
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Re: [R] from character string to function body?
Atte Tenkanen said the following on 7/7/2007 8:41 AM:
Dear R users,
I wonder if it is possible to form a function from a character string. Here
is an example:
x=3
`-`(`+`(`^`(x,3),`^`(x,2)),1) # Here is my function evaluated.
[1] 35
V=list(`-`,(,`+`,(,`^`,(,x,,,3,),,,`^`,(,x,,,2,),),,,1,))
# Here I construct the string, it could be vector as well?
S=noquote(paste(V,collapse=))
S
[1] `-`(`+`(`^`(x,3),`^`(x,2)),1) # Here is the same as a character string.
Now I'd like to create a function using this string, something like this, but
of course, this doesn't work:
S=as.expression(S)
F1-function(x){S}
Is there some way to do this?
Cheers,
Atte Tenkanen
University of Turku, Finland
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
How about:
V -
list(`-`,(,`+`,(,`^`,(,x,,,3,),,,`^`,(,x,,,2,),),,,1,))
# Here I construct the string, it could be vector as well?
S - paste(V, collapse = )
F1 - function(x) {}
body(F1) - parse(text = S)
F1(3)
# [1] 35
F1(2)
# [1] 11
HTH,
--sundar
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] from character string to function body?
Thanks Sundar!
I wonder that - when evaluating F1 - the right mathematical formula is now also
printed!
F1
function (x)
x^3 + x^2 - 1
Atte
Atte Tenkanen said the following on 7/7/2007 8:41 AM:
Dear R users,
I wonder if it is possible to form a function from a character
string. Here is an example:
x=3
`-`(`+`(`^`(x,3),`^`(x,2)),1) # Here is my function evaluated.
[1] 35
V=list(`-
`,(,`+`,(,`^`,(,x,,,3,),,,`^`,(,x,,,2,),),,,1,))
# Here I construct the string, it could be vector as well?
S=noquote(paste(V,collapse=))
S
[1] `-`(`+`(`^`(x,3),`^`(x,2)),1) # Here is the same as a
character string.
Now I'd like to create a function using this string, something
like this, but of course, this doesn't work:
S=as.expression(S)
F1-function(x){S}
Is there some way to do this?
Cheers,
Atte Tenkanen
University of Turku, Finland
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-
guide.html and provide commented, minimal, self-contained,
reproducible code.
How about:
V -
list(`-
`,(,`+`,(,`^`,(,x,,,3,),,,`^`,(,x,,,2,),),,,1,))
# Here I construct the string, it could be vector as well?
S - paste(V, collapse = )
F1 - function(x) {}
body(F1) - parse(text = S)
F1(3)
# [1] 35
F1(2)
# [1] 11
HTH,
--sundar
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
