--- a/numerics/histogram.py	Sat Feb 28 17:05:04 2015 -0800
+++ b/numerics/histogram.py	Sat Feb 28 21:28:17 2015 -0800
@@ -33,16 +33,17 @@
     """historgram"""
 
     def __init__(self, bins):
-        bins = sorted(bin)
+        self.bins = sorted(bins)
         assert len(bins) > 1
-        self.data = self.OrderedDict(zip(bins[:-1],
-                                         bins[1:]))
+        self.data = OrderedDict([(bin, [])
+                                 for bin in zip(bins[:-1],
+                                                bins[1:])])
 
     def add(self, *values):
         """add values to the histogram"""
         for value in values:
             for vmin, vmax in self.data.keys():
-                if vmin <= value <= vmax:
+                if vmin <= value < vmax:
                     self.data[(vmin, vmax)].append(value)
 
     def __iadd__(self, value):
@@ -55,6 +56,11 @@
         OrderedDict of counts
         """
         self.add(*values)
+        return OrderedDict([(bin, len(value))
+                            for bin, value in self.data.items()])
+
+    def keys(self):
+        return self.data.keys()
 
 class HistogramParser(CSVParser):
     """histogram CLI option parser"""