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import numpy as np |
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def py_cpu_nms(dets, thresh): |
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"""Pure Python NMS baseline.""" |
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x1 = dets[:, 0] |
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y1 = dets[:, 1] |
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x2 = dets[:, 2] |
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y2 = dets[:, 3] |
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scores = dets[:, 4] |
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areas = (x2 - x1 + 1) * (y2 - y1 + 1) |
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order = scores.argsort()[::-1] |
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keep = [] |
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while order.size > 0: |
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i = order[0] |
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keep.append(i) |
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xx1 = np.maximum(x1[i], x1[order[1:]]) |
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yy1 = np.maximum(y1[i], y1[order[1:]]) |
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xx2 = np.minimum(x2[i], x2[order[1:]]) |
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yy2 = np.minimum(y2[i], y2[order[1:]]) |
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w = np.maximum(0.0, xx2 - xx1 + 1) |
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h = np.maximum(0.0, yy2 - yy1 + 1) |
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inter = w * h |
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ovr = inter / (areas[i] + areas[order[1:]] - inter) |
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inds = np.where(ovr <= thresh)[0] |
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order = order[inds + 1] |
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return keep |
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