Problems

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Intersection over Union (IoU)

Metrics & EvaluationComputer Vision

Easy

Compute Intersection over Union for two axis-aligned boxes. Each box is given as $[x_1,y_1,x_2,y_2]$ , where the first point is the top-left corner and the second is the bottom-right corner.

A_{\mathrm{intersection}}=\max(0,x_R-x_L)\max(0,y_B-y_T)

A_{\mathrm{union}}=A_A+A_B-A_{\mathrm{intersection}}

\operatorname{IoU}=\frac{A_{\mathrm{intersection}}}{A_{\mathrm{union}}}

Here, $x_L$ and $y_T$ are the largest starting coordinates, while $x_R$ and $y_B$ are the smallest ending coordinates. Return zero when the union is zero. Otherwise return IoU as a Python float.

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Examples

Input: box_a = [0, 0, 4, 4], box_b = [2, 2, 6, 6]

Output: 0.142857

Explanation: The intersection area is 4 and the union area is 28.

Input: box_a = [0, 0, 2, 2], box_b = [3, 3, 5, 5]

Output: 0

Hint 1

Use maximum starting coordinates and minimum ending coordinates for the intersection.

Hint 2

Compute union with area_a + area_b - intersection.

Requirements

Compute the overlapping width and height without allowing negative values
Compute both box areas and their union
Return zero for a zero-area union
Return IoU as a float

Constraints

Each box contains four numeric coordinates
The ending coordinate is not smaller than the corresponding starting coordinate

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