Merge branch 'dc-lambdas'

dcchart.md

@@ -0,0 +1,43 @@
+# how to use dcchart
+
+dcchart is an embedded domain specific language for creating interactive
+[dc.js](http://nickqizhu.github.com/dc.js/) charts from R.
+
+Currently it is mostly a transcription of the javascript into R.
+
+Here's an example of a (meaningless) set of three charts:
+
+
+    data <- list(list(2008, "a", 8), list(2008, "c", 5), list(2009, "b", 12), list(2009, 
+        "a", 1), list(2010, "c", 17));
+    wdcchart(data,
+    charts(
+    dimension(one,func(d)(d[0])),
+    dimension(two,func(d)(d[1])),
+    dimension(three,func(d)(d[2])),
+    domain(twoD,uniques(two)),
+    domain(threeD,uniques(three)),
+    pie(width(180)
+          $height(180)
+          $radius(80)
+          $dimension(one)
+          $group(one$group()$reduceCount())),
+    bar(width(500)
+          $height(100)
+          $margins(hash(top:20,right:50,bottom:20,left:40))
+          $dimension(two)
+          $group(two$group()$reduceCount())
+          $centerBar(false)
+          $gap(0)
+          $x(d3$scale$ordinal()$domain(twoD))
+          $xUnits(dc$units$ordinal)),
+    bar(width(500)
+          $height(100)
+          $margins(hash(top:20,right:50,bottom:20,left:40))
+          $dimension(two)
+          $group(two$group()$reduceSum(func(d)(d[2])))
+          $centerBar(false)
+          $gap(0)
+          $x(d3$scale$ordinal()$domain(twoD))
+          $xUnits(dc$units$ordinal))
+    ))

htdocs/dcrchart.js

@@ -15,30 +15,41 @@ var dcrchart = (function() {
     function una_or_bin_op(disp) {
         return function(args) {
             return args.length==2 
-                ? '-' + translate_expr(args[1])
-                : bin_op('-')(args); 
+                ? disp + translate_expr(args[1])
+                : bin_op(disp)(args); 
         }
     }
 
-    var translators = {
+    function translate_kv(kv) {
+        if(!$.isArray(kv) || kv[0] != ':' || typeof kv[1] != "string")
+            throw "expected 'key = value' in dc/r hash";
+        return kv[1] + ': ' + translate_expr(kv[2]);
+    }
+
+    var expressions = {
         "$": bin_op('.'),
         "-": una_or_bin_op('-'),
         "+": una_or_bin_op('+'),
         "*": bin_op('*'),
         "/": bin_op('/'),
+        "[": function(args) { return translate_expr(args[1]) + '[' + translate_expr(args[2]) + ']'; },
         "hash": function(args) { return '{' + _.map(args.slice(1), translate_kv) + '}'; },
         default : function(args) { return translate_expr(args[0]) + '(' +  _.map(args.slice(1), translate_expr) + ')'; } 
     };
 
-    function translate_kv(kv) {
-        if(!$.isArray(kv) || kv[0] != ':' || typeof kv[1] != "string")
-            throw "expected 'key = value' in dc/r hash";
-        return kv[1] + ': ' + translate_expr(kv[2]);
+    function translate_function(sexp) {
+        var args = sexp[0].slice(1),
+            body = _.map(sexp.slice(1), translate_expr);
+        var text = "function (" + args.join() + ") { " + body.slice(0, -1).join("; ") + 
+            "return " + body[body.length-1] + "; }";
+        return text;
     }
 
     function translate_expr(sexp) {
         if($.isArray(sexp)) {
-            var xlat = translators[sexp[0]] || translators.default;
+            if($.isArray(sexp[0]) && sexp[0][0] == "func") // special case function expr trees
+                return translate_function(sexp)
+            var xlat = expressions[sexp[0]] || expressions.default;
             return xlat(sexp);
         }
         else return sexp;
@@ -97,10 +108,20 @@ var dcrchart = (function() {
         return domains[sexp[0]](sexp);
     }
 
+    function chart_handler(prefix, constructor) {
+        return function(result, sexp) {
+            var name = prefix + chart_group + '_' + result.chart_no++;
+            var chart_code = translate_chart(name, constructor, sexp[1]);
+            result.charts.push(chart_code);
+            result.divs.push(make_chart_div(name))
+            return result;
+        }
+    }
+
     var statements = {
         dimension: function(result, sexp) {
-            result.decls.push(make_var(sexp[1]) + "ndx.dimension(function(d) { return " + 
-                              translate_dimension(sexp[2]) + "; })");
+            result.decls.push(make_var(sexp[1]) + "ndx.dimension(" +
+                              translate_expr(sexp[2]) + ")");
             return result;
         },
         domain: function(result, sexp) {
@@ -125,7 +146,7 @@ var dcrchart = (function() {
             var result = _.reduce(sexp.slice(1), 
                                   translate_statement, 
                                   charts_result);
-            var js = "debugger;\n" +
+            var js = // "debugger;\n" +  
                 "var ndx = crossfilter(rows);\n" + 
                 result.decls.join(";\n") + ";\n" +
                 result.charts.join(";\n") + ";\n" +