Getting problem to load numpy file in pytorch

I am very new in the Deep learning and Pytorch platform. I have started a project related to image classification with CNN , for this reason I would like to load my custom data set( a folder which contain 4000 numpy files) In Pytorch. I used DatasetFolder as a reference. But I am unable to load my dataset.
Here is my code

import torch
import torchvision
from import DataLoader, Sampler
from torchvision import datasets
from torchvision.transforms import transforms

import matplotlib.pyplot as plt
import numpy as np

DATA_TRAIN = '/home/mchow/Downloads/homework/data/pp'

def npy_loader(path):
    sample = torch.from_numpy(np.load(path))
    return sample

dataset = datasets.DatasetFolder(


But I got the following errors.I could not solve this problem.

Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "/home/mchow/Downloads/pycharm-professional-2019.1.3/pycharm-2019.1.3/helpers/pydev/_pydev_bundle/", line 197, in runfile
    pydev_imports.execfile(filename, global_vars, local_vars)  # execute the script
  File "/home/mchow/Downloads/pycharm-professional-2019.1.3/pycharm-2019.1.3/helpers/pydev/_pydev_imps/", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "/home/mchow/Downloads/Assignment", line 29, in <module>
  File "/home/mchow/miniconda3/lib/python3.6/site-packages/torchvision/datasets/", line 75, in __init__
    classes, class_to_idx = find_classes(root)
  File "/home/mchow/miniconda3/lib/python3.6/site-packages/torchvision/datasets/", line 23, in find_classes
    classes = [d for d in os.listdir(dir) if os.path.isdir(os.path.join(dir, d))]
FileNotFoundError: [Errno 2] No such file or directory: 'DATA_TRAIN'

I will be very grateful,if any one help me out .

Try to set root=DATA_TRAIN instead of the string 'DATA_TRAIN'.

Thank you so much @ptrblck , Now this code worked.