ENH: Allow left and right arguments to numpy.interp to be functions

[jhamman]

It would be useful to allow numpy.interp to take a (optional) function for the left/right arguments. This would allow user specified handling of the tails in interpolations operations.

(sorry I somehow submitted this issue prematurely, I have edited the summary now.)

[eric-wieser]

Alternatively, perhaps it should just take arrays that broadcast to x? So the call would become:

np.interp(x, xp, fp, left=f_left(x), right=f_right(x))

Yes, this means computing values that might not be needed, but it also means that the computation of those values is vectorized

[SpoorthyBhat]

How exactly would this work? Do you mean f_left(x) and f_right(x) produce arrays of the same length as x and the required values are picked up?