added a function makedirs() to snli example which works both for python 2 and 3

snli/train.py

@@ -10,7 +10,7 @@
 from torchtext import datasets
 
 from model import SNLIClassifier
-from util import get_args
+from util import get_args, makedirs
 
 
 args = get_args()
@@ -27,7 +27,7 @@
         inputs.vocab.vectors = torch.load(args.vector_cache)
     else:
         inputs.vocab.load_vectors(wv_dir=args.data_cache, wv_type=args.word_vectors, wv_dim=args.d_embed)
-        os.makedirs(os.path.dirname(args.vector_cache), exist_ok=True)
+        makedirs(os.path.dirname(args.vector_cache))
         torch.save(inputs.vocab.vectors, args.vector_cache)
 answers.build_vocab(train)
 
@@ -59,7 +59,7 @@
 header = '  Time Epoch Iteration Progress    (%Epoch)   Loss   Dev/Loss     Accuracy  Dev/Accuracy'
 dev_log_template = ' '.join('{:>6.0f},{:>5.0f},{:>9.0f},{:>5.0f}/{:<5.0f} {:>7.0f}%,{:>8.6f},{:8.6f},{:12.4f},{:12.4f}'.split(','))
 log_template =     ' '.join('{:>6.0f},{:>5.0f},{:>9.0f},{:>5.0f}/{:<5.0f} {:>7.0f}%,{:>8.6f},{},{:12.4f},{}'.split(','))
-os.makedirs(args.save_path, exist_ok=True)
+makedirs(args.save_path)
 print(header)
 
 for epoch in range(args.epochs):

snli/util.py

@@ -1,6 +1,23 @@
 import os
 from argparse import ArgumentParser
 
+def makedirs(name):
+    """helper function for python 2 and 3 to call os.makedirs()
+       avoiding an error if the directory to be created already exists"""
+
+    import os, errno
+
+    try:
+        os.makedirs(name)
+    except OSError as ex:
+        if ex.errno == errno.EEXIST and os.path.isdir(name):
+            # ignore existing directory
+            pass
+        else:
+            # a different error happened
+            raise
+
+
 def get_args():
     parser = ArgumentParser(description='PyTorch/torchtext SNLI example')
     parser.add_argument('--epochs', type=int, default=50)