== R

Interface to R
[[toc:]]
=== Overview
{{R}} provides a simple way to call R-functions, consisting of the following two forms: {{R}} and {{R*}}. {{R}} evaluates an R-expression, returning an opaque R-pointer that can be passed to other R-functions. Use this, for instance, when you don't need to modify the object in Scheme.


{{R*}}, on the other hand, evaluates the expression and tries to translate it into Scheme; it understands {{NULL}}, lists, strings, reals, bools, complex numbers and symbols. Everything else is opaque.


=== Documentation
==== {{NA}}
<constant>NA → (make-NA)</constant>
NA corresponds to R's NA.
<enscript highlight="scheme">(define NA (make-NA))
</enscript>
===== Examples
Don't forget to quasiquote:
 (R* (is.na (c 1 ,NA)))
==== {{R-missing}}
<constant>R-missing → (foreign-value R_MissingArg SEXP)</constant>
R-constant for missing arguments
<enscript highlight="scheme">(define R-missing (foreign-value "R_MissingArg" SEXP))
</enscript>
===== Examples
Selecting columns of matrices; corresponds to {{sum(complete.cases(airquality[, -1]))}}:
 (R* (sum (complete.cases (|[| airquality ,R-missing 1))))
==== {{R-null}}
<constant>R-null → (foreign-value R_NilValue SEXP)</constant>
NULL
<enscript highlight="scheme">(define R-null (foreign-value "R_NilValue" SEXP))
</enscript>
===== Examples
Empty list is not null:
 (R* (is.null (list)))
{{NULL}}, on the other hand:
 (R* (is.null ,R-null))
==== {{R}}
<syntax>(R expression ...) → R-object</syntax>
Evaluate R-expressions, but do not try to translate the final
result into a native Scheme object; this is useful when you don't need
to manipulate the object directly in Scheme.
; expression : An expression to evaluate
; ... : More expressions
<enscript highlight="scheme">(define-syntax
  R
  (lambda (expression rename compare)
    `(begin
       ,@(map (lambda (expression) `(R-eval ,(list 'quasiquote expression)))
              (cdr expression)))))
</enscript>
===== Examples
An example from {{ggplot2}}; see [[https://raw.github.com/klutometis/R/master/doc/ggplot.png|here]]:
 (R (library "ggplot2")
    (plot
     (qplot (factor ($ mtcars cyl))
            ($ mtcars wt)
            xlab:
            "Number of cylinders"
            ylab:
            "Weight (lb/1000)"
            main:
            "1974 Motor Trend car-comparison"
            data:
            mtcars
            geom:
            (c "boxplot" "jitter"))))
Another plotting example; see [[https://raw.github.com/klutometis/R/master/doc/plot.png|here]]:
 (let ((x (R (sort (rnorm 47)))))
   (R
    (plot ,x xlab: "i" ylab: "Random normals" type: "s" main: "Primitive ECDF")
    (points ,x cex: 0.5 col: "dark red")))
==== {{R*}}
<syntax>(R* expression ...) → Scheme-object</syntax>
Evaluate R-expressions and translate the final result into a
Scheme object, where possible (cf. [[#overview]]); use this (as opposed
to {{R}}) when you need to manipulate the value in Scheme.
; expression : An expression to evaluate
; ... : More expressions
<enscript highlight="scheme">(define-syntax
  R*
  (lambda (expression rename compare) `(R->scheme (R ,@(cdr expression)))))
</enscript>
===== Examples
An example using classical statistics:
 (let* ((x (R (runif 100 0 10))) (y (R (+ 2 (+ (* 3 ,x) (rnorm 100)))))
                                 (df (R (data.frame x: ,x y: ,y)))
                                 (d (R (lm (as.formula "y ~ x") data: ,df))))
   (R* ($ (summary ,d) "cov.unscaled")))
=== About this egg

==== Author

[[/users/klutometis|Peter Danenberg]]
==== Repository
[[https://github.com/klutometis/R]]
==== License
BSD
==== Dependencies
* [[big-chicken]]
* [[call-with-environment-variables]]
* [[cock]]
* [[debug]]
* [[define-record-and-printer]]
* [[matchable]]
* [[moremacros]]
* [[numbers]]
* [[shell]]

==== Versions
; [[https://github.com/klutometis/R/releases/tag/0.1|0.1]] : Initial release
; [[https://github.com/klutometis/R/releases/tag/0.1.1|0.1.1]] : Add cock.
; [[https://github.com/klutometis/R/releases/tag/0.1.2|0.1.2]] : Clean up animation code.
; [[https://github.com/klutometis/R/releases/tag/0.1.3|0.1.3]] : Set R_HOME, if necessary.
; [[https://github.com/klutometis/R/releases/tag/0.2|0.2]] : R- and R*-forms.
; [[https://github.com/klutometis/R/releases/tag/0.2.1|0.2.1]] : Use the new R-eval forms.
; [[https://github.com/klutometis/R/releases/tag/0.2.2|0.2.2]] : With a note about cock-utils
; [[https://github.com/klutometis/R/releases/tag/0.3|0.3]] : NA, NaN, inf
; [[https://github.com/klutometis/R/releases/tag/0.3.1|0.3.1]] : Rid of aima; NA in lists
; [[https://github.com/klutometis/R/releases/tag/0.3.2|0.3.2]] : Some examples in the docs
; [[https://github.com/klutometis/R/releases/tag/0.3.3|0.3.3]] : Using sjamaan's idea about integer instead of int for 32-bit machines.
; [[https://github.com/klutometis/R/releases/tag/0.3.4|0.3.4]] : Multiple R-expressions
; [[https://github.com/klutometis/R/releases/tag/0.3.5|0.3.5]] : Blindly trying to fix NA for 32-bit.
; [[https://github.com/klutometis/R/releases/tag/0.3.6|0.3.6]] : Add test-exit.
==== Colophon

Documented by [[/egg/cock|cock]].