32 lines
1.0 KiB
Python
32 lines
1.0 KiB
Python
from typing import Sequence
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import numpy as np
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def get_anchor_grid(
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num_rows: int,
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num_cols: int,
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scale_factor: float,
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anchor_widths: Sequence[float],
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aspect_ratios: Sequence[float],
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) -> np.ndarray:
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anchor_grid = np.empty(
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[len(anchor_widths), len(aspect_ratios), num_rows, num_cols, 4], dtype=float)
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for (width_idx, ratio_idx, row, col) in np.ndindex(anchor_grid.shape[:-1]):
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anchor_point = (
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col * scale_factor + scale_factor / 2, row * scale_factor + scale_factor / 2)
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width = anchor_widths[width_idx]
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ratio = aspect_ratios[ratio_idx]
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anchor_grid[width_idx, ratio_idx, row, col] = get_box(
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width, ratio, anchor_point)
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return anchor_grid
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def get_box(width: float, ratio: float, anchor_point: tuple[float, float]) -> np.ndarray:
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box = np.empty(4, dtype=float)
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box[0] = anchor_point[0] - (width / 2)
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box[1] = anchor_point[1] - (width * ratio / 2)
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box[2] = anchor_point[0] + (width / 2)
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box[3] = anchor_point[1] + (width * ratio / 2)
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return box
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