h5py.File() gives error message

[C W]

Dear list,

The following Python code gives an error message

# Python code starts here:
import numpy as np
import h5py
train_dataset = h5py.File('datasets/train_catvnoncat.h5', "r")

# Python code ends

The error message:

train_dataset = h5py.File('train_catvnoncat.h5', "r")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/M/anaconda/lib/python3.6/site-packages/h5py/_hl/files.py",
line 269, in __init__
    fid = make_fid(name, mode, userblock_size, fapl, swmr=swmr)
  File "/Users/M/anaconda/lib/python3.6/site-packages/h5py/_hl/files.py",
line 99, in make_fid
    fid = h5f.open(name, flags, fapl=fapl)
  File "h5py/_objects.pyx", line 54, in h5py._objects.with_phil.wrapper
  File "h5py/_objects.pyx", line 55, in h5py._objects.with_phil.wrapper
  File "h5py/h5f.pyx", line 78, in h5py.h5f.open
OSError: Unable to open file (unable to open file: name =
'train_catvnoncat.h5', errno = 2, error message = 'No such file or
directory', flags = 0, o_flags = 0)

My directory is correct, and the dataset folder with file is there.

Why error message? Is it h5py.File() or is it my file? Everything seems
pretty simple, what's going on?

Thank you!