histogram: Fill weights array by zeros before putting weight values

Fix #21

Author: mrkn

ext/enumerable/statistics/extension/statistics.c

@@ -2284,7 +2284,7 @@ ary_histogram(int argc, VALUE *argv, VALUE ary)
 {
   VALUE arg0, opts, edge, weights;
   int left_p;
-  long nbins;
+  long nbins, nweights, i;
 
   rb_scan_args(argc, argv, "01:", &arg0, &opts);
   if (NIL_P(arg0)) {
@@ -2296,7 +2296,13 @@ ary_histogram(int argc, VALUE *argv, VALUE ary)
   left_p = opt_closed_left_p(opts);
 
   edge = ary_histogram_calculate_edge(ary, nbins, left_p);
-  weights = rb_ary_new_capa(RARRAY_LEN(edge) - 1);
+
+  nweights = RARRAY_LEN(edge) - 1;
+  weights = rb_ary_new_capa(nweights);
+  for (i = 0; i < nweights; ++i) {
+    rb_ary_store(weights, i, INT2FIX(0));
+  }
+
   histogram_weights_push_values(weights, edge, ary, left_p);
 
   return rb_struct_new(cHistogram, edge, weights,

spec/histogram/array_spec.rb

@@ -51,6 +51,19 @@
     end
   end
 
+  with_array [1, 2] do
+    context 'closed: :left' do
+      let(:args) { [{closed: :left}] }
+
+      specify do
+        expect(histogram.edge).to eq([1.0, 1.5, 2.0, 2.5])
+        expect(histogram.weights).to eq([1, 0, 1])
+        expect(histogram.closed).to eq(:left)
+        expect(histogram.density?).to eq(false)
+      end
+    end
+  end
+
   with_array [1, 2, 3, 4, 5, 6, 7, 8, 9] do
     context 'default' do
       specify do