Is there some special subtlety or edge case where a hand rolled function will go wrong? I like the SO version spelled like this (a little fleshed out):

def clamp(val, min_val=None, max_val=None):
    min_val = val if min_val is None else min_val
    max_val = val if max_val is None else max_val
    assert min_val <= max_val
    return max(min(val , max_val), min_val)

On Sat, Jul 30, 2016 at 2:57 PM, Neil Girdhar <mistersheik@gmail.com> wrote:

It's common to want to clip (or clamp) a number to a range.  This feature is commonly needed for both floating point numbers and integers:

http://stackoverflow.com/questions/9775731/clamping-floating-numbers-in-python

http://stackoverflow.com/questions/4092528/how-to-clamp-an-integer-to-some-range-in-python

There are a few approaches: 

* use a couple ternary operators (e.g. https://github.com/scipy/scipy/pull/5944/files  line 98, which generated a lot of discussion)

* use a min/max construction,

* call sorted on a list of the three numbers and pick out the first, or

* use numpy.clip. 

Am I right that there is no *obvious* way to do this?  If so, I suggest adding math.clip (or math.clamp) to the standard library that has the meaning:

def clip(number, lower, upper):

    return lower if number < lower else upper if number > upper else number

This would work for non-numeric types so long as the non-numeric types support comparison.  It might also be worth adding

assert lower < upper

to catch some bugs.

Best,

Neil

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