比较与torchvision.datasets.CocoDetection的差异
torchvision.datasets.CocoDetection
class torchvision.datasets.CocoDetection(
root: str,
annFile: str,
transform: Optional[Callable]=None,
target_transform: Optional[Callable]=None,
transforms: Optional[Callable]=None
)
mindspore.dataset.CocoDataset
class mindspore.dataset.CocoDataset(
dataset_dir,
annotation_file,
task="Detection",
num_samples=None,
num_parallel_workers=None,
shuffle=None,
decode=False,
sampler=None,
num_shards=None,
shard_id=None,
cache=None,
extra_metadata=False,
decrypt=None
)
差异对比
PyTorch:输入COCO格式数据集,返回创建出的数据集对象,可通过遍历数据集对象获取数据。
MindSpore:输入COCO格式数据集及指定任务类型(目标检测,全景分割等),返回给定任务类型的数据集对象,可通过创建迭代器获取数据。
分类 |
子类 |
PyTorch |
MindSpore |
差异 |
---|---|---|---|---|
参数 |
参数1 |
root |
dataset_dir |
- |
参数2 |
annFile |
annotation_file |
- |
|
参数3 |
transform |
- |
MindSpore通过 |
|
参数4 |
target_transform |
- |
MindSpore通过 |
|
参数5 |
transforms |
- |
MindSpore通过 |
|
参数6 |
- |
task |
指定COCO数据的任务类型 |
|
参数7 |
- |
num_samples |
指定从数据集中读取的样本数 |
|
参数8 |
- |
num_parallel_workers |
指定读取数据的工作线程数 |
|
参数9 |
- |
shuffle |
指定是否混洗数据集 |
|
参数10 |
- |
decode |
指定是否对图像进行解码 |
|
参数11 |
- |
sampler |
指定采样器 |
|
参数12 |
- |
num_shards |
指定分布式训练时将数据集进行划分的分片数 |
|
参数13 |
- |
shard_id |
指定分布式训练时使用的分片ID号 |
|
参数14 |
- |
cache |
指定单节点数据缓存服务 |
|
参数15 |
- |
extra_metadata |
用于指定是否额外输出一个数据列用于表示图片元信息 |
|
参数16 |
- |
decrypt |
图像解密函数 |
代码示例
import mindspore.dataset as ds
import torchvision.datasets as datasets
import torchvision.transforms as T
# In MindSpore, CocoDataset supports four kinds of tasks, which are Object Detection, Keypoint Detection, Stuff Segmentation and Panoptic Segmentation of 2017 Train/Val/Test dataset.
coco_dataset_dir = "/path/to/coco_dataset_directory/images"
coco_annotation_file = "/path/to/coco_dataset_directory/annotation_file"
# Read COCO data for Detection task. Output columns: [image, dtype=uint8], [bbox, dtype=float32], [category_id, dtype=uint32], [iscrowd, dtype=uint32]
dataset = ds.CocoDataset(
dataset_dir=coco_dataset_dir,
annotation_file=coco_annotation_file,
task='Detection',
decode=True,
shuffle=False,
extra_metadata=True)
dataset = dataset.rename("_meta-filename", "filename")
file_name = []
bbox = []
category_id = []
iscrowd = []
for data in dataset.create_dict_iterator(num_epochs=1, output_numpy=True):
file_name.append(data["filename"])
bbox.append(data["bbox"])
category_id.append(data["category_id"])
iscrowd.append(data["iscrowd"])
print(file_name[0])
print(bbox[0])
print(category_id[0])
print(iscrowd[0])
# out:
# 000000391895
# [[10. 10. 10. 10.]
# [70. 70. 70. 70.]]
# [[1]
# [7]]
# [[0]
# [0]]
# In torch, the output will be result of transform, eg. Tensor
root = "/path/to/coco_dataset_directory/images"
annFile = "/path/to/coco_dataset_directory/annotation_file"
# Convert a PIL Image or numpy.ndarray to tensor.
dataset = datasets.CocoDetection(root, annFile, transform=T.ToTensor())
for item in dataset:
print("item:", item[0])
break
# out:
# loading annotations into memory...
# Done (t=0.00s)
# creating index...
# index created!
# item: tensor([[[0.8588, 0.8549, 0.8549, ..., 0.7529, 0.7529, 0.7529,
# [0.8549, 0.8549, 0.8510, ..., 0.7529, 0.7529, 0.7529],
# [0.8549, 0.8510, 0.8510, ..., 0.7529, 0.7529, 0.7529],
# ...,
#
# ...,
# [0.8471, 0.8510, 0.8549, ..., 0.7412, 0.7333, 0.7294],
# [0.8549, 0.8549, 0.8549, ..., 0.7412, 0.7333, 0.7294],
# [0.8627, 0.8627, 0.8549, ..., 0.7412, 0.7333, 0.7294]]])