set default backend. (#1104)

apps/kg/eval.py

@@ -8,7 +8,7 @@ import logging
 import time
 import pickle
 
-backend = os.environ.get('DGLBACKEND')
+backend = os.environ.get('DGLBACKEND', 'pytorch')
 if backend.lower() == 'mxnet':
     from train_mxnet import load_model_from_checkpoint
     from train_mxnet import test

apps/kg/models/general_models.py

@@ -2,7 +2,7 @@ import os
 import numpy as np
 import dgl.backend as F
 
-backend = os.environ.get('DGLBACKEND')
+backend = os.environ.get('DGLBACKEND', 'pytorch')
 if backend.lower() == 'mxnet':
     from .mxnet.tensor_models import logsigmoid
     from .mxnet.tensor_models import get_device

apps/kg/tests/test_score.py

@@ -5,7 +5,7 @@ import numpy as np
 import dgl.backend as F
 import dgl
 
-backend = os.environ.get('DGLBACKEND')
+backend = os.environ.get('DGLBACKEND', 'pytorch')
 if backend.lower() == 'mxnet':
     import mxnet as mx
     mx.random.seed(42)

apps/kg/train.py

@@ -6,7 +6,7 @@ import os
 import logging
 import time
 
-backend = os.environ.get('DGLBACKEND')
+backend = os.environ.get('DGLBACKEND', 'pytorch')
 if backend.lower() == 'mxnet':
     import multiprocessing as mp
     from train_mxnet import load_model