Implemented prop.

sethyuan · Apr 2, 2013 · b107406 · b107406
1 parent cad7028
commit b107406
Show file tree

Hide file tree

Showing 2 changed files with 87 additions and 0 deletions.
diff --git a/lib/xtabs.js b/lib/xtabs.js
@@ -386,4 +386,53 @@ var addMargins = function(table, margins, fun) {
   return Object.freeze(new Table(dim, dimnames, array));
 };
 
+var prop = function(table, margin) {
+  var array = new Array(table.array.length);
+  if (margin == null) {
+    var total = 0;
+    for (var i = 0; i < table.array.length; i++) {
+      total += table.array[i];
+    }
+    for (var i = 0; i < array.length; i++) {
+      array[i] = table.array[i] / total;
+    }
+  } else {
+    var blockSize = margin + 1 < table.dim.length ? table.dim[margin + 1] : 1;
+    for (var i = margin + 2; i < table.dim.length; i++) {
+      blockSize *= table.dim[i];
+    }
+    var numberOfBlocks = margin - 1 >= 0 ? table.dim[margin - 1] : 1;
+    for (var i = margin - 2; i >= 0; i--) {
+      numberOfBlocks *= table.dim[i];
+    }
+    var jumpSize = 1;
+    for (var i = margin; i < table.dim.length; i++) {
+      jumpSize *= table.dim[i];
+    }
+    debugger;
+
+    var calcGroup = function(group) {
+      var sum = 0;
+      for (var i = 0; i < numberOfBlocks; i++) {
+        for (var j = 0; j < blockSize; j++) {
+          var pos = group * blockSize + i * jumpSize + j;
+          sum += table.array[pos];
+        }
+      }
+      for (var i = 0; i < numberOfBlocks; i++) {
+        for (var j = 0; j < blockSize; j++) {
+          var pos = group * blockSize + i * jumpSize + j;
+          array[pos] = table.array[pos] / sum;
+        }
+      }
+    };
+
+    for (var i = 0; i < table.dim[margin]; i++) {
+      calcGroup(i);
+    }
+  }
+  return Object.freeze(new Table(table.dim, table.dimnames, array));
+};
+
 exports.addMargins = addMargins;
+exports.prop = prop;
diff --git a/test/xtabs.js b/test/xtabs.js
@@ -220,6 +220,44 @@ describe("xtabs", function() {
     });
   });
 
+  describe("prop", function() {
+    var data = {
+      department: xtabs.factor(["MIS", "MIS", "HR", "TR", null, "TR", "MIS"]),
+      team: xtabs.factor(["Oversea", "PO", "HR", "Tech", null, "Tech", "PO"]),
+      gender: xtabs.factor(["M", "F", "F", "M", "F", "M", "M"])
+    };
+
+    it("proportions of the whole", function() {
+      var t = xtabs.table(data, "department", "gender");
+      var t_ = xtabs.prop(t);
+      t_.array.should.eql([2/6, 1/6, 0, 1/6, 2/6, 0]);
+    });
+
+    it("proportions of the row", function() {
+      var t = xtabs.table(data, "department", "gender");
+      var t_ = xtabs.prop(t, 0);
+      t_.array.should.eql([2/3, 1/3, 0, 1, 1, 0]);
+    });
+
+    it("proportions of the column", function() {
+      var t = xtabs.table(data, "department", "gender");
+      var t_ = xtabs.prop(t, 1);
+      t_.array.should.eql([.5, .5, 0, .5, .5, 0]);
+    });
+
+    it("proportions of margin 2", function() {
+      var t = xtabs.table(data, "department", "team", "gender");
+      var t_ = xtabs.prop(t, 2);
+      t_.get("MIS").array.should.eql([1/4, 0, 1/4, 1/2, 0, 0, 0, 0]);
+    });
+
+    it("single dimension", function() {
+      var t = xtabs.table(data, "gender");
+      var t_ = xtabs.prop(t);
+      t_.array.should.eql([4/7, 3/7]);
+    });
+  });
+
   describe("addMargins", function() {
     var data = {
       department: xtabs.factor(["MIS", "MIS", "HR", "TR", null, "TR", "MIS"]),