stats

saucebrush/stats.py

@@ -0,0 +1,46 @@
+from saucebrush.filters import Filter
+
+class StatsFilter(Filter):
+    
+    def __init__(self, field, test=None):
+        self._field = field
+        self._test = test if test else lambda x: True
+        
+    def process_record(self, record):
+        if self._test(record):
+            self.process_field(record[self._field])
+        return record
+    
+    def process_field(self, record):
+        raise NotImplementedError('process_field not defined in ' +
+                                  self.__class__.__name__)
+    
+    def value(self):
+        raise NotImplementedError('value not defined in ' +
+                                  self.__class__.__name__)
+
+class Sum(StatsFilter):
+    
+    def __init__(self, field, initial=0, **kwargs):
+        super(Sum, self).__init__(field, **kwargs)
+        self._value = initial
+        
+    def process_field(self, item):
+        self._value += item or 0
+        
+    def value(self):
+        return self._value
+
+class Average(StatsFilter):
+    
+    def __init__(self, field, initial=0, **kwargs):
+        super(Average, self).__init__(field, **kwargs)
+        self._value = initial
+        self._count = 0
+        
+    def process_field(self, item):
+        self._value += item or 0
+        self._count += 1
+        
+    def value(self):
+        return self._value / self._count