sort python imports with isort

pcdet/models/backbones_3d/pfe/voxel_set_abstraction.py

 import torch
 import torch.nn as nn
-from ....utils import common_utils
+
 from ....ops.pointnet2.pointnet2_stack import pointnet2_modules as pointnet2_stack_modules
 from ....ops.pointnet2.pointnet2_stack import pointnet2_utils as pointnet2_stack_utils
+from ....utils import common_utils
 
 
 def bilinear_interpolate_torch(im, x, y):
@@ -236,4 +237,3 @@ class VoxelSetAbstraction(nn.Module):
         batch_dict['point_features'] = point_features  # (BxN, C)
         batch_dict['point_coords'] = point_coords  # (BxN, 4)
         return batch_dict
-

pcdet/models/backbones_3d/pointnet2_backbone.py

 import torch
 import torch.nn as nn
+
 from ...ops.pointnet2.pointnet2_batch import pointnet2_modules
 from ...ops.pointnet2.pointnet2_stack import pointnet2_modules as pointnet2_modules_stack
 from ...ops.pointnet2.pointnet2_stack import pointnet2_utils as pointnet2_utils_stack

pcdet/models/backbones_3d/spconv_backbone.py

-import torch.nn as nn
-import spconv
 from functools import partial
 
+import spconv
+import torch.nn as nn
+
 
 def post_act_block(in_channels, out_channels, kernel_size, indice_key=None, stride=1, padding=0,
                    conv_type='subm', norm_fn=None):

pcdet/models/backbones_3d/spconv_unet.py

+from functools import partial
+
+import spconv
 import torch
 import torch.nn as nn
-import spconv
-from functools import partial
-from .spconv_backbone import post_act_block
+
 from ...utils import common_utils
+from .spconv_backbone import post_act_block
 
 
 class SparseBasicBlock(spconv.SparseModule):

pcdet/models/backbones_3d/vfe/__init__.py

-from .vfe_template import VFETemplate
 from .mean_vfe import MeanVFE
 from .pillar_vfe import PillarVFE
+from .vfe_template import VFETemplate
 
 __all__ = {
     'VFETemplate': VFETemplate,

pcdet/models/backbones_3d/vfe/mean_vfe.py

 import torch
+
 from .vfe_template import VFETemplate
 
 

pcdet/models/backbones_3d/vfe/pillar_vfe.py

 import torch
 import torch.nn as nn
 import torch.nn.functional as F
+
 from .vfe_template import VFETemplate
 
 

pcdet/models/dense_heads/__init__.py

-from .anchor_head_template import AnchorHeadTemplate
+from .anchor_head_multi import AnchorHeadMulti
 from .anchor_head_single import AnchorHeadSingle
-from .point_intra_part_head import PointIntraPartOffsetHead
-from .point_head_simple import PointHeadSimple
+from .anchor_head_template import AnchorHeadTemplate
 from .point_head_box import PointHeadBox
-from .anchor_head_multi import AnchorHeadMulti
+from .point_head_simple import PointHeadSimple
+from .point_intra_part_head import PointIntraPartOffsetHead
 
 __all__ = {
     'AnchorHeadTemplate': AnchorHeadTemplate,

pcdet/models/dense_heads/anchor_head_multi.py

 import numpy as np
+import torch
 import torch.nn as nn
-from .anchor_head_template import AnchorHeadTemplate
+
 from ..backbones_2d import BaseBEVBackbone
-import torch
+from .anchor_head_template import AnchorHeadTemplate
 
 
 class SingleHead(BaseBEVBackbone):

pcdet/models/dense_heads/anchor_head_single.py

 import numpy as np
 import torch.nn as nn
+
 from .anchor_head_template import AnchorHeadTemplate
 
 
@@ -72,4 +73,3 @@ class AnchorHeadSingle(AnchorHeadTemplate):
             data_dict['cls_preds_normalized'] = False
 
         return data_dict
-

pcdet/models/dense_heads/anchor_head_template.py

 import numpy as np
 import torch
 import torch.nn as nn
+
+from ...utils import box_coder_utils, common_utils, loss_utils
 from .target_assigner.anchor_generator import AnchorGenerator
 from .target_assigner.atss_target_assigner import ATSSTargetAssigner
 from .target_assigner.axis_aligned_target_assigner import AxisAlignedTargetAssigner
-from ...utils import box_coder_utils, loss_utils, common_utils
 
 
 class AnchorHeadTemplate(nn.Module):

pcdet/models/dense_heads/point_head_box.py

 import torch
-from .point_head_template import PointHeadTemplate
+
 from ...utils import box_coder_utils, box_utils
+from .point_head_template import PointHeadTemplate
 
 
 class PointHeadBox(PointHeadTemplate):

pcdet/models/dense_heads/point_head_simple.py

 import torch
-from .point_head_template import PointHeadTemplate
+
 from ...utils import box_utils
+from .point_head_template import PointHeadTemplate
 
 
 class PointHeadSimple(PointHeadTemplate):

pcdet/models/dense_heads/point_head_template.py

 import torch
 import torch.nn as nn
 import torch.nn.functional as F
-from ...utils import loss_utils, common_utils
+
 from ...ops.roiaware_pool3d import roiaware_pool3d_utils
+from ...utils import common_utils, loss_utils
 
 
 class PointHeadTemplate(nn.Module):

pcdet/models/dense_heads/point_intra_part_head.py

 import torch
+
+from ...utils import box_coder_utils, box_utils
 from .point_head_template import PointHeadTemplate
-from ...utils import box_utils, box_coder_utils
 
 
 class PointIntraPartOffsetHead(PointHeadTemplate):

pcdet/models/dense_heads/target_assigner/atss_target_assigner.py

 import torch
-from ....utils import common_utils
+
 from ....ops.iou3d_nms import iou3d_nms_utils
+from ....utils import common_utils
 
 
 class ATSSTargetAssigner(object):

pcdet/models/dense_heads/target_assigner/axis_aligned_target_assigner.py

-import torch
 import numpy as np
-from ....utils import box_utils
+import torch
+
 from ....ops.iou3d_nms import iou3d_nms_utils
+from ....utils import box_utils
 
 
 class AxisAlignedTargetAssigner(object):
@@ -210,5 +211,3 @@ class AxisAlignedTargetAssigner(object):
             'reg_weights': reg_weights,
         }
         return ret_dict
-
-

pcdet/models/detectors/__init__.py

 from .detector3d_template import Detector3DTemplate
-from .second_net import SECONDNet
 from .PartA2_net import PartA2Net
-from .pv_rcnn import PVRCNN
-from .pointpillar import PointPillar
 from .point_rcnn import PointRCNN
+from .pointpillar import PointPillar
+from .pv_rcnn import PVRCNN
+from .second_net import SECONDNet
 
 __all__ = {
     'Detector3DTemplate': Detector3DTemplate,

pcdet/models/detectors/detector3d_template.py

-import torch
 import os
+
+import torch
 import torch.nn as nn
-from .. import backbones_3d, backbones_2d, dense_heads, roi_heads
-from ..backbones_3d import vfe, pfe
+
+from ...ops.iou3d_nms import iou3d_nms_utils
+from .. import backbones_2d, backbones_3d, dense_heads, roi_heads
 from ..backbones_2d import map_to_bev
+from ..backbones_3d import pfe, vfe
 from ..model_utils import model_nms_utils
-from ...ops.iou3d_nms import iou3d_nms_utils
 
 
 class Detector3DTemplate(nn.Module):

pcdet/models/model_utils/model_nms_utils.py

 import torch
+
 from ...ops.iou3d_nms import iou3d_nms_utils