find_varfunc {lazy.symbolic}

R Documentation

Find Variables and Functions in an Expression

Description

Find Variables and Functions in an Expression

Usage

find_varfunc(
  expr,
  func = 0,
  mark = 0,
  markchar = c("V", "F"),
  debug = 0,
  print = 0
)

Arguments

expr	An input expression as a (scalar) string.
func	= 1 to return the functions with nesting level info
mark	= 1 to mark the found ones.
markchar	A character vector of length=2, The first one is for variable, the 2nd, function.
debug	= 1 to print the intermediate results.
print	= 1 to print the result.

Value

A list of
expr (marked) input expression
varlist a list or variables/functions in expr
is.function indicator vector: is.function[i]=1 if varlist[i] is a function
fromto the range of the variables/functions
bp the location of the left and the right parens for functions

In addition, if func=1,
fname function name.
fpnum parent function number.
fpname parent function name.
flevel function level: (flevel=1 means the top level.)
fbody function body (with enclosing parens).

Examples

find_varfunc("-a(10)+b1*c2-d(x)", mark=0, print=1)
find_varfunc("-a(10)+b1*c2-d(x)", mark=1, print=1)
find_varfunc("a-b+1*(c-d-1*(e+f)-g)+1*(h1(x+g(y))+(i+j))", mark=1, print=1)

expr="-BB+f(C1-D)-a*gg(h1(EE)+P+h2(XX-q(y)))-H"
res=find_varfunc( expr, print=1, func=1)

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