import numpy as np
[docs]def iou(bbox1: np.array, bbox2: np.array) -> float:
"""
Calculates the intersection-over-union of two bounding boxes.
Args:
bbox1 (numpy.array, list of floats): bounding box in format x1,y1,x2,y2.
bbox2 (numpy.array, list of floats): bounding box in format x1,y1,x2,y2.
Returns:
float: intersection-over-onion of bbox1, bbox2
"""
bbox1 = [float(x) for x in bbox1]
bbox2 = [float(x) for x in bbox2]
(x0_1, y0_1, x1_1, y1_1) = bbox1
(x0_2, y0_2, x1_2, y1_2) = bbox2
# get the overlap rectangle
overlap_x0 = max(x0_1, x0_2)
overlap_y0 = max(y0_1, y0_2)
overlap_x1 = min(x1_1, x1_2)
overlap_y1 = min(y1_1, y1_2)
# check if there is an overlap
if overlap_x1 - overlap_x0 <= 0 or overlap_y1 - overlap_y0 <= 0:
return 0
# if yes, calculate the ratio of the overlap to each ROI size and the unified size
size_1 = (x1_1 - x0_1) * (y1_1 - y0_1)
size_2 = (x1_2 - x0_2) * (y1_2 - y0_2)
size_intersection = (overlap_x1 - overlap_x0) * (overlap_y1 - overlap_y0)
size_union = size_1 + size_2 - size_intersection
return size_intersection / size_union