equation2function
converts the righthand side of an equation that can be written
as a single line (like the righthand side of an object of class formula
) and
creates an R function which calls the variables within as arguments and returns values
consistent with the parameters of the input equation as written.
1  equation2function(equation, envir = parent.frame(), notName = "XXXXXXXXXXX")

equation 
The righthandside (RHS) of an equation, given as a character string.
If not of type character, 
envir 
The environment the resulting function will be evaluated in.
See 
notName 
A useless string used simply as a placeholder in turning 
This simple little function is rather hacky but seems to get the job done, for a functionality that doesn't seem to be present elsewhere in R.
A function, with named blank (i.e. no default value) arguments.
David W. Bapst
1 2 3 4 5 6 7 8 9 10 11 12 13  # some simple examples
foo<equation2function("x+y")
foo
foo(x=4,y=0.1)
foo<equation2function("x+2*sqrt(2*y+3)^2")
foo
foo(x=4,y=0.1)
# what about weird long argument names and spaces
foo<equation2function("stegosaur + 0.4 * P")
foo
foo(stegosaur=5,P=0.3)

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