def gen_base_anchors(self):
    'Generate base anchors.\n\n        Returns:\n            list(torch.Tensor): Base anchors of a feature grid in multiple                 feature levels.\n        '
    multi_level_base_anchors = []
    for (i, base_size) in enumerate(self.base_sizes):
        base_anchors = self.gen_single_level_base_anchors(base_size, scales=self.scales[i], ratios=self.ratios[i], center=self.centers[i])
        indices = list(range(len(self.ratios[i])))
        indices.insert(1, len(indices))
        base_anchors = torch.index_select(base_anchors, 0, torch.LongTensor(indices))
        multi_level_base_anchors.append(base_anchors)
    return multi_level_base_anchors
Generate base anchors.

Returns:
    list(torch.Tensor): Base anchors of a feature grid in multiple                 feature levels.
def gen_base_anchors(self):
    'Generate base anchors.\n\n        Returns:\n            list(torch.Tensor): Base anchors of a feature grid in multiple                 feature levels.\n        '
    multi_level_base_anchors = []
    for (i, base_size) in enumerate(self.base_sizes):
        base_anchors = self.gen_single_level_base_anchors(base_size, scales=self.scales[i], ratios=self.ratios[i], center=self.centers[i])
        indices = list(range(len(self.ratios[i])))
        indices.insert(1, len(indices))
        base_anchors = torch.index_select(base_anchors, 0, torch.LongTensor(indices))
        multi_level_base_anchors.append(base_anchors)
    return multi_level_base_anchors