[SciPy-user] histogram(a, normed=True) doesn't normalize?

Robert Kern robert.kern at gmail.com
Mon Jun 19 21:46:46 CDT 2006


Martin Spacek wrote:
> David Huard wrote:
> 
>>Yes.
>>
>>The normalization constant is not the sum of the bin, but the sum of the 
>>product of the bin count with the bin width :
>>\sum_i  f_i * delta_i
> 
> It seems I long ago forgot the distinction between a probability 
> *distribution* function and a probability *density* function. I assumed 
> they were the same thing. Thanks for the clarification.

No, they're the same (more or less). However, what you were asking about (bins
sum to 1) is a probability *mass* function.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth."
  -- Umberto Eco



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