14 lines
353 B
Python
14 lines
353 B
Python
>>> class SD(object): # Plain () for python 3.x
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def __init__(self):
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self.sum, self.sum2, self.n = (0,0,0)
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def sd(self, x):
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self.sum += x
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self.sum2 += x*x
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self.n += 1.0
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sum, sum2, n = self.sum, self.sum2, self.n
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return sqrt(sum2/n - sum*sum/n/n)
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>>> sd_inst = SD()
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>>> for value in (2,4,4,4,5,5,7,9):
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print (value, sd_inst.sd(value))
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