init

ostat/__init__.py

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+from .ostat import OnlineStat

ostat/ostat.py

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+import math
+
+
+class OnlineStat(object):
+    def __init__(self):
+        self.n = 0.0
+
+        self.min = float('inf')
+        self.max = float('-inf')
+
+        self.old_m = 0.0
+        self.old_s = 0.0
+
+        self.new_m = 0.0
+        self.new_s = 0.0
+
+    def push(self, x):
+        self.n += 1
+
+        if x < self.min:
+            self.min = x
+        if x > self.max:
+            self.max = x
+
+        self.new_m = self.old_m + (x - self.old_m) / self.n
+        self.new_s = self.old_s + (x - self.old_m) * (x - self.new_m)
+
+        self.old_m = self.new_m
+        self.old_s = self.new_s
+
+    @property
+    def mean(self):
+        return self.new_m if self.n > 0 else 0.0
+
+    @property
+    def variance(self):
+        return self.new_s / (self.n) if self.n > 1 else 0.0
+
+    @property
+    def stddev(self):
+        return math.sqrt(self.variance)
+
+    def __unicode__(self):
+        return u'{min} {mean} {max} {stddev}'.format(
+            min=self.min,
+            mean=self.mean,
+            max=self.max,
+            stddev=self.stddev,
+        )
+
+    def __str__(self):
+        return u'{}'.format(self).encode('utf8')
+
+    def __repr__(self):
+        return u'<OnlineStat {}>'.format(self)