ENH: Arithmetic operations on intervals #43629

pandas/_libs/interval.pyx

@@ -489,6 +489,69 @@ cdef class Interval(IntervalMixin):
             )
         ):
             return Interval(y.left + self, y.right + self, closed=y.closed)
+        if (
+            isinstance(self, Interval)
+            and isinstance(y, Interval)
+        ):
+            # Check if both intervals intersect at a point taking into account of closed
+            # and open intersection points
+            is_intersecting = (
+                self.overlaps(y)
+                or ((self.left == y.right) and ((self.closed in ["left", "both"])
+                    or (y.closed in ["right", "both"])))
+                or ((y.left == self.right)
+                    and ((y.closed in ["left", "both"])
+                    or (self.closed in ["right", "both"])))
+            )
+            # If the intervals intersect, return one new interval that contains
+            # all elements
+            if(is_intersecting):
+                # Obtain the new interval's left hand side by taking the min of both
+                # intervals left hand side
+                left_closed = None
+                left = None
+                if(y.left < self.left):
+                    left = y.left
+                    left_closed = y.closed in ["left", "both"]
+                elif (y.left > self.left):
+                    left = self.left
+                    left_closed = self.closed in ["left", "both"]
+                else:
+                    left = self.left
+                    left_closed = (y.closed in ["left", "both"]
+                                   or self.closed in ["left", "both"])
+                # Obtain the new interval's right hand side by taking the max of
+                # both intervals right hand side
+                right_closed = None
+                right = None
+                if(y.right > self.right):
+                    right = y.right
+                    right_closed = y.closed in ["right", "both"]
+                elif (y.right < self.right):
+                    right = self.right
+                    right_closed = self.closed in ["right", "both"]
+                else:
+                    right = self.right
+                    right_closed = (y.closed in ["right", "both"]
+                                    or self.closed in ["right", "both"])
+
+                closed = None
+                if left_closed and right_closed:
+                    closed = "both"
+                elif left_closed:
+                    closed = "left"
+                elif right_closed:
+                    closed = "right"
+                else:
+                    closed = "neither"
+
+                return Interval(left, right, closed=closed)
+
+            # Return a list of the intervals in sorted order if they don't intersect
+            first_interval = y if y.left < self.left else self
+            second_interval = y if first_interval == self else self
+            return [first_interval, second_interval]
+
         return NotImplemented
 
     def __radd__(self, other):
@@ -507,6 +570,159 @@ cdef class Interval(IntervalMixin):
             or is_timedelta64_object(y)
         ):
             return Interval(self.left - y, self.right - y, closed=self.closed)
+
+        if isinstance(y, list) and isinstance(self, Interval):
+            # If the list is empty, return the interval
+            if not y:
+                return self
+            # If the list is not empty, return the difference between self and
+            # each interval in the y list
+            else:
+                new_interval = []
+                for interval in y:
+                    new_interval.append(self - interval)
+                return new_interval
+        if isinstance(self, list) and isinstance(y, Interval):
+            # If the list is empty, return the interval
+            if not self:
+                return y
+            # If the list is not empty, return the difference between each interval
+            # in the list and the y interval
+            else:
+                new_interval = []
+                for interval in self:
+                    new_interval.append(interval - y)
+                return new_interval
+        if isinstance(self, list) and isinstance(y, list):
+            # If the list is empty, return the interval
+            if not self:
+                return y
+            # If the list is not empty, return the difference between each interval
+            # in the list and each interval in the y list
+            else:
+                new_interval = []
+                for interval in self:
+                    for interval2 in y:
+                        new_interval.append(interval - interval2)
+                return new_interval
+        # Performs set difference on the two intervals
+        if (
+            isinstance(self, Interval)
+            and isinstance(y, Interval)
+        ):
+            if not self.overlaps(y):
+                return self
+            else:
+                # If the right side of the interval is the same, an empty interval
+                # is returned
+                if (y.left == self.left and y.right == self.right
+                        or y.left < self.left and y.right > self.right):
+                    return Interval(0, 0, closed="neither")
+                # If the left side of the interval is the same, return the right
+                # side of the interval
+                if (y.left == self.left and y.right < self.right):
+                    if (y.closed in ["left", "neither"]
+                            and self.closed in ["right", "both"]):
+                        return Interval(y.right, self.right, closed="both")
+                    if y.closed in ["right", "both"]
+                    and self.closed in ["right", "both"]:
+                        return Interval(y.right, self.right, closed="right")
+                    if y.closed in ["left", "neither"]
+                    and self.closed in ["left", "neither"]:
+                        return Interval(y.right, self.right, closed="left")
+                    if y.closed in ["right", "both"]
+                    and self.closed in ["left", "neither"]:
+                        return Interval(y.right, self.right, closed="neither")
+                # If the right side of the interval is the same,
+                # return the left side of the interval
+                if (y.left > self.left and y.right == self.right):
+                    if y.closed in ["right", "neither"]
+                    and self.closed in ["left", "both"]:
+                        return Interval(self.left, y.left, closed="both")
+                    if y.closed in ["left", "both"] and self.closed in ["left", "both"]:
+                        return Interval(self.left, y.left, closed="left")
+                    if y.closed in ["right", "neither"]
+                    and self.closed in ["right", "neither"]:
+                        return Interval(self.left, y.left, closed="right")
+                    if y.closed in ["left", "both"]
+                    and self.closed in ["right", "neither"]:
+                        return Interval(self.left, y.left, closed="neither")
+                interval_split = False
+                left_closed = None
+                left = None
+                if(y.left < self.left and y.right < self.right):
+                    # lefy of y is left of self and right of y is in self
+                    left = y.right
+                    left_closed = y.closed not in ["right", "both"]
+                elif (y.left > self.left and y.right > self.right):
+                    # left of y is in self and right of y is right of self
+                    left = self.left
+                    left_closed = self.closed in ["left", "both"]
+                else:
+                    # left of y is in self and right of y is in self
+                    # This will split the interval into two
+                    interval_split = True
+
+                right_closed = None
+                right = None
+                if(y.left > self.left and y.right > self.right):
+                    # left of y is right of self and right of y is right of self
+                    right = y.left
+                    right_closed = y.closed not in ["left", "both"]
+                elif (y.left < self.left and y.right < self.right):
+                    # left of y is left of self and right of y is in self
+                    right = self.right
+                    right_closed = self.closed in ["right", "both"]
+                else:
+                    # left of y is in self and right of y is in self
+                    # This will split the interval into two
+                    interval_split = True
+
+                # If the interval needs to be split, return two intervals with
+                # the correct closed values
+                def create_new_intervals(y_closed, self_closed):
+                    closed_cases = {
+                        ("left", "left"): ("left", "left"),
+                        ("left", "right"): ("neither", "both"),
+                        ("left", "both"): ("left", "both"),
+                        ("left", "neither"): ("neither", "left"),
+                        ("right", "left"): ("both", "neither"),
+                        ("right", "right"): ("right", "right"),
+                        ("right", "both"): ("both", "right"),
+                        ("right", "neither"): ("right", "neither"),
+                        ("both", "left"): ("left", "neither"),
+                        ("both", "right"): ("neither", "right"),
+                        ("both", "both"): ("left", "right"),
+                        ("both", "neither"): ("neither", "neither"),
+                        ("neither", "left"): ("both", "left"),
+                        ("neither", "right"): ("right", "both"),
+                        ("neither", "both"): ("both", "both"),
+                        ("neither", "neither"): ("right", "left")
+                    }
+                    return closed_cases[(y_closed, self_closed)]
+
+                if interval_split:
+                    new_interval = []
+                    left_interval_closed, right_interval_closed
+                    = create_new_intervals(y.closed, self.closed)
+                    new_interval.append
+                    (Interval(self.left, y.left, closed=left_interval_closed))
+                    new_interval.append
+                    (Interval(y.right, self.right, closed=right_interval_closed))
+                    return new_interval
+
+                # If the interval is not split, return a single interval
+                if left_closed:
+                    if right_closed:
+                        closed = "both"
+                    else:
+                        closed = "left"
+                else:
+                    if right_closed:
+                        closed = "right"
+                    else:
+                        closed = "neither"
+                return Interval(left, right, closed=closed)
         return NotImplemented
 
     def __mul__(self, y):
@@ -516,6 +732,75 @@ cdef class Interval(IntervalMixin):
             # __radd__ semantics
             # TODO(cython3): remove this
             return Interval(y.left * self, y.right * self, closed=y.closed)
+        if (
+            isinstance(self, Interval)
+            and isinstance(y, Interval)
+        ):
+            # If the intervals overlap, return the overlapping interval
+            if(self.overlaps(y)):
+                closed = None
+                left=0
+                left_closed=None
+                right=0
+                right_closed=None
+                # If the left side of the interval is the same,
+                # return the right side of the interval
+                if (self.left<y.left):
+
+                    left= y.left
+                    left_closed=y.closed
+                    # If the right side of the interval is the same,
+                    # return the left side of the interval
+                    if (self.right<y.right):
+                        right= self.right
+                        right_closed=self.closed
+                    # If the right side of the interval is not the same,
+                    # return the right side of the interval
+                    else:
+                        right=y.right
+                        right_closed=y.closed
+                        if(left_closed=="right" and right_closed=="right"):
+                            closed="right"
+                        if(left_closed=="left" and right_closed=="left"):
+                            closed="left"
+                # If the left side of the interval is not the same,
+                # return the left side of the interval
+                else :
+                    left=self.left
+                    left_closed=self.closed
+                    # If the right side of the interval is the same,
+                    # return the left side of the interval
+                    if (self.right<y.right):
+                        right= self.right
+                        right_closed=self.closed
+                        if(left_closed=="right" and right_closed=="right"):
+                            closed="right"
+                        if(left_closed=="left" and right_closed=="left"):
+                            closed="left"
+                    # If the right side of the interval is not the same,
+                    # return the right side of the interval
+                    else:
+                        right=y.right
+                        right_closed=y.closed
+                # If the closed value is not set, set it
+                if cond is None:
+                    if (left_closed=="neither" and right_closed=="neither"):
+                        closed = "neither"
+                    elif (right_closed=="right" and left_closed=="neither")
+                    or (right_closed=="both" and left_closed=="neither"):
+                        closed = "right"
+                    elif (left_closed=="left" and right_closed=="neither")
+                    or (left_closed=="both" and right_closed=="neither"):
+                        closed = "left"
+                    elif (left_closed=="both" or right_closed=="both"):
+                        closed = "both"
+                    else:
+                        closed = "neither"
+                # Return the interval
+                return Interval(left, right, closed=closed)
+            # If the intervals do not overlap, return an empty interval
+            return Interval(0, 0, closed="neither")
+
         return NotImplemented
 
     def __rmul__(self, other):

pandas/core/arrays/interval.py

@@ -622,6 +622,47 @@ def from_tuples(
 
         return cls.from_arrays(left, right, closed, copy=False, dtype=dtype)
 
+    # Return the intersection of all the intervals in the IntervalArray
+    def product(self):
+        # If the array is empty, return an empty array
+        return_array = self[0]
+        for i in range(1, len(self)):
+            # If the intersection of the current interval and the
+            # previous interval is not empty
+            if (return_array * self[i]) != Interval(0, 0, closed="neither"):
+                return_array = return_array * self[i]
+            # If the intersection of the current interval and the
+            # previous interval is empty
+            else:
+                if return_array != self[0]:
+                    break
+                else:
+                    return_array = Interval(0, 0, "neither")
+        # If the intersection of all the intervals is empty
+        return IntervalArray([return_array])
+
+    # Return the simplified union of all the intervals
+    # in the IntervalArray in ascending order
+    def sum(self):
+        # If there is only one interval in the array,
+        # then return a new IntervalArray with that one interval
+        if len(self) < 2:
+            return IntervalArray([self[0]])
+        # Sort the intervals in the IntervalArray in ascending order
+        sorted_indices = self.argsort(ascending=True)
+        output = [self[sorted_indices[0]]]
+        for i in sorted_indices[1:]:
+            prev = output.pop()
+            # Sums the current interval with the last
+            # interval in the intermediary sum list
+            cur = self[sorted_indices[i]]
+            tmp = prev + cur
+            if isinstance(tmp, Interval):
+                output.append(tmp)
+            elif isinstance(tmp, list):
+                output = output + tmp
+        return IntervalArray(output)
+
     @classmethod
     def _validate(cls, left, right, dtype: IntervalDtype) -> None:
         """