Make torchaudio work on Python 2. (#209)

- Apply __future__ imports uniformly (future division is the biggy, but absolute
  imports mattered too)
- Hotfix use of tempfile.TemporaryDirectory using a BC library (DO NOT
  add this library as a dependency to torchaudio; it's only for testing)
- Replace math.gcd with fractions.gcd
- Fix a weird pytest collection bug involving parametrized tests
- Turn on Python 2 and Python 3.7 in Travis.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>

.travis.yml

@@ -12,10 +12,11 @@ cache:
 matrix:
   fast_finish: true
   include:
-    # TODO add this back in when there is a pytorch 1.2 for python 3.5
-    # - env: PYTHON_VERSION="3.5"
+    - env: PYTHON_VERSION="3.7"
     - env: PYTHON_VERSION="3.6"
+    # TODO add this back in when there is a pytorch 1.2 for python 3.5
     - env: PYTHON_VERSION="3.5" RUN_FLAKE8="true" SKIP_TESTS="true"
+    - env: PYTHON_VERSION="2.7"
 
 addons:
   apt:

requirements.txt

@@ -14,4 +14,7 @@ librosa>=0.4.3
 scipy
 
 # Unit tests with pytest
-pytest
+pytest
\ No newline at end of file
+
+# Testing only Py3 compat
+backports.tempfile

test/common_utils.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import os
 from shutil import copytree
-import tempfile
+import backports.tempfile as tempfile
 import torch
 
 TEST_DIR_PATH = os.path.dirname(os.path.realpath(__file__))

test/compliance/generate_fbank_data.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import argparse
 import logging
 import os

test/compliance/generate_test_stft_data.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import argparse
 import logging
 import os

test/compliance/utils.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import random
 import torchaudio
 

test/test.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import unittest
 import common_utils
 import torch

test/test_compliance_kaldi.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import math
 import os
 import common_utils

test/test_dataloader.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import unittest
 import common_utils
 import torch

test/test_datasets_vctk.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import os
 
 import torch

test/test_functional.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import math
 
 import torch
@@ -195,15 +196,18 @@ def _num_stft_bins(signal_len, fft_len, hop_length, pad):
     return (signal_len + 2 * pad - fft_len + hop_length) // hop_length
 
 
-@pytest.mark.parametrize('rate', [0.5, 1.01, 1.3])
 @pytest.mark.parametrize('complex_specgrams', [
     torch.randn(1, 2, 1025, 400, 2),
     torch.randn(1, 1025, 400, 2)
 ])
+@pytest.mark.parametrize('rate', [0.5, 1.01, 1.3])
 @pytest.mark.parametrize('hop_length', [256])
-@unittest.skipIf(not IMPORT_LIBROSA, 'Librosa is not available')
 def test_phase_vocoder(complex_specgrams, rate, hop_length):
 
+    # Using a decorator here causes parametrize to fail on Python 2
+    if not IMPORT_LIBROSA:
+        raise unittest.SkipTest('Librosa is not available')
+
     # Due to cummulative sum, numerical error in using torch.float32 will
     # result in bottom right values of the stretched sectrogram to not
     # match with librosa.

test/test_jit.py

-from __future__ import division
+from __future__ import absolute_import, division, print_function, unicode_literals
 import torch
 import torchaudio.functional as F
 import torchaudio.transforms as transforms

test/test_kaldi_io.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import os
 import torch
 import torchaudio.kaldi_io as kio

test/test_sox_effects.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import unittest
 import common_utils
 import torch

test/test_transforms.py

-from __future__ import print_function
+from __future__ import absolute_import, division, print_function, unicode_literals
 import math
 import os
 

torchaudio/__init__.py

-from __future__ import division, print_function
+from __future__ import absolute_import, division, print_function, unicode_literals
 import os.path
 
 import torch

torchaudio/_docs.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import torchaudio
 
 

torchaudio/common_utils.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import sys
 
 PY3 = sys.version_info > (3, 0)

torchaudio/compliance/kaldi.py

+from __future__ import absolute_import, division, print_function, unicode_literals
 import math
+import fractions
 import random
 import torch
 
@@ -600,7 +602,7 @@ def _get_LR_indices_and_weights(orig_freq, new_freq, output_samples_in_unit, win
 
 
 def _lcm(a, b):
-    return abs(a * b) // math.gcd(a, b)
+    return abs(a * b) // fractions.gcd(a, b)
 
 
 def _get_num_LR_output_samples(input_num_samp, samp_rate_in, samp_rate_out):
@@ -675,7 +677,7 @@ def resample_waveform(waveform, orig_freq, new_freq, lowpass_filter_width=6):
 
     assert lowpass_cutoff * 2 <= min_freq
 
-    base_freq = math.gcd(int(orig_freq), int(new_freq))
+    base_freq = fractions.gcd(int(orig_freq), int(new_freq))
     input_samples_in_unit = int(orig_freq) // base_freq
     output_samples_in_unit = int(new_freq) // base_freq
 

torchaudio/datasets/vctk.py

-from __future__ import print_function
+from __future__ import absolute_import, division, print_function, unicode_literals
 import torch.utils.data as data
 import os
 import os.path