As submitted to CRAN

Author: billdenney

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: formulops
 Title: Mathematical Operations on R Formula
-Version: 0.0.0.9003
+Version: 0.5.0
 Authors@R: person("Bill", "Denney", email="wdenney@humanpredictions.com", role=c("aut", "cre"), comment=c(ORCID="0000-0002-5759-428X"))
 Description: Perform mathematical operations on R formula (add, subtract, multiply, etc.) and substitute parts of formula.
 Depends: R (>= 3.5)
@@ -11,3 +11,5 @@ RoxygenNote: 7.0.2
 Suggests:
     covr,
     testthat
+URL: https://github.com/billdenney/formulops
+BugReports: https://github.com/billdenney/formulops/issues

README.md

@@ -22,9 +22,25 @@ install.packages("formulops")
 
 ## Example
 
-This is a basic example which shows you how to solve a common problem:
+A few common examples of modifying a formula are given below.
 
 ``` r
 library(formulops)
-## basic example code
+# Replace a with c in the formula
+modify_formula(a~b, find=quote(a), replace=quote(c))
+# Replace a with c+d in the formula
+modify_formula(a~b, find=quote(a), replace=quote(c+d))
+# More complex parts can be replaced, too
+modify_formula(a~b/c, find=quote(b/c), replace=quote(d))
+# Multiple replacements can occur simultaneously
+modify_formula(a~b/c+d, find=list(quote(b/c), quote(d)), replace=list(quote(d), quote(e)))
+# Function arguments can be expanded
+modify_formula(a~b(c), find=quote(c), replace=quote(formulops_expand(d, e)))
+```
+
+A substituting formula is a simple way to generate a complex formula from several simpler formulae.  Parentheses are appropriately added, if required.
+
+``` r
+foo <- substituting_formula(y~x1+x2, x1~x3*x4, x2~x5/x6+x7)
+as.formula(foo)
 ```