python - Get intersection range of two non-discrete intervals -

given interval defined start , end point (both floats), determine intersection range second interval. example:

int1 = [2. , 5.]  int2 = [2.2, 7.]  >>> desired_function(int1, int2) 2.8 

it should handle intersection possibilities (no intersection, partial intersection, complete intersection, negative ranges etc.). attempt looks this:

def intersection(int1, int2):      #case 1: partial intersection on left or right border     if (int2[0]<=int1[0] , int2[1]<=int1[1]) or (int2[0]>=int1[0] , int2[1]>=int1[1]):         return min(int1[1],int2[1]) - max(int1[0],int2[0])      #case 2: complete overlap of 1 interval other     elif (int2[0]>=int1[0] , int2[1]<=int1[1]) or (int2[0]<=int1[0] , int2[1]>=int1[1]):         return min (int2[1]-int2[0] , int1[1]-int1[0])      #case 3: no overlap @     else:         return 0 

question: have missed , there build-in solution or package similar since want keep code simple , fast possible?

you making things complicated, simple function is:

def interval_intersect(a,b):     a0,a1 =     b0,b1 = b     return max(0,min(a1,b1)-max(a0,b0)) 

we calculate maximum of start of 2 intervals , minimum of end between these intervals. calculate difference , use max(0,...) make sure if there no interval, return 0.

we can generalize function further into:

from operator import itemgetter  def interval_intersect(*args):     return max(0,min(map(itemgetter(1),args))-max(map(itemgetter(0),args))) 

to let work arbitrary number of intervals. these both give:

>>> interval_intersect((2,5),(2.2,7)) 2.8