1 Error description

1.1 System Environment

ardware Environment(Ascend/GPU/CPU): CPU
Software Environment:
– MindSpore version (source or binary): 1.6.0
– Python version (eg, Python 3.7.5): 3.7.6
– OS platform and distribution (eg, Linux Ubuntu 16.04): Ubuntu 4.15.0-74-generic
– GCC/Compiler version (if compiled from source):

1.2 Basic information

1.2.1 Script

This case uses the mindspore.dataset custom dataset:

import os
import numpy as np
from PIL import Image
import mindspore.common.dtype as mstype
import mindspore.dataset as ds
import mindspore.dataset.transforms.c_transforms as C
import mindspore.dataset.vision.c_transforms as vc

class _dcp_Dataset:
    def __init__(self,img_root_dir,device_target="CPU"):
        if not os.path.exists(img_root_dir):
            raise RuntimeError(f"the input image dir {img_root_dir} is invalid")
        self.img_root_dir=img_root_dir
        self.img_names=[i for i in os.listdir(img_root_dir) if i.endswith(".jpg")]
        self.target=device_target

    def __len__(self):
        return len(self.img_names)

    def __getitem__(self, index):
        img_name=self.img_names[index]
        im=Image.open(os.path.join(self.img_root_dir,img_name))
        image=np.array(im)
        label_str=img_name.split("_")[-1]
        label_str=label_str.split(".")[0]
        label=np.array(label_str)
        return image,label

def creat_dataset(dataset_path,batch_size=2,num_shards=1,shard_id=0,device_target="CPU"):
    dataset=_dcp_Dataset(dataset_path,device_target)
    data_set=ds.GeneratorDataset(dataset,["image","label"],shuffle=True,num_shards=1,shard_id=0)
    image_trans=[
        vc.Resize((224,224)),
        vc.RandomHorizontalFlip(),
        vc.Rescale(1/255,shift=0),
        vc.Normalize((0.4465, 0.4822, 0.4914), (0.2010, 0.1994, 0.2023)),
        vc.HWC2CHW
    ]
    label_trans=[C.TypeCast(mstype.int32)]

    data_set=data_set.map(operations=image_trans,input_columns=["image"])
    data_set=data_set.map(operations=label_trans,input_columns=["label"])
    # data_set=data_set.shuffle(buffer_size=batch_size)
    data_set=data_set.batch(batch_size=batch_size,drop_remainder=True)
    # data_set=data_set.repeat(1)

    return data_set


if __name__ == '__main__':
   data=creat_dataset("./image_DCP")
   print(data)
   data_loader = data.create_dict_iterator()
   for i, data in enumerate(data_loader): 
        print(i)
        print(data)

1.2.2 Error reporting

Error message:

2 Reason analysis and solution

There is a lack of () here, change the code here to vc.HWC2CHW() to execute normally.

3 Summary

Steps to locate the problem

For example: there is a data processing flow such as xxDataset -> map -> map -> batch.
Scripts can be debugged as follows:

Only keep xxDataset, and then run the script to see if an error is reported;
Keep xxDataset -> map, and then run the script to see if an error is reported;
Keep xxDataset -> map -> map, and then run the script to see if an error is reported;
Keep xxDataset -> map -> map -> batch, and then run the script to see if an error is reported;

According to the above method, you can locate which map/batch is wrong.

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