python: generating a histogram

this:

 numpy.histogram([1,3,2,3,1,1,1,1,2,3,2,5,6,6],bins=numpy.arange(0,7,1))
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yields:

(array([0, 5, 3, 3, 0, 3]), array([0, 1, 2, 3, 4, 5, 6]))

why does it count three 6's? there are only 2!

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because bins defines the bin edges you need to add one more bin

numpy.histogram([1,3,2,3,1,1,1,1,2,3,2,5,6,6],bins=numpy.arange(0,8,1))

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There is one 5 and two 6's in the last bin. Quoting the doc "All but the last (righthand-most) bin is half-open", so the last bin includes the 2 6's.

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I believe this is related to the semantics of the first and last bins being underflow and overflow. Your total bucket count is correct.

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It looks like it's lumping the 5's and 6's together - maybe the last bin is 5 to 6, inclusive?

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Edit: Looking at the docs, I'm guessing that 6 is the rightmost edge, so values between five and six are in that final bin.