add gpu_id flag in demo/gan

demo/gan/gan_trainer_image.py

@@ -184,13 +184,16 @@ def main():
     parser.add_argument("-d", "--dataSource", help="mnist or cifar")
     parser.add_argument("--useGpu", default="1", 
                         help="1 means use gpu for training")
+    parser.add_argument("--gpuId", default="0", 
+                        help="the gpu_id parameter")
     args = parser.parse_args()
     dataSource = args.dataSource
     useGpu = args.useGpu
     assert dataSource in ["mnist", "cifar"]
     assert useGpu in ["0", "1"]
             
-    api.initPaddle('--use_gpu=' + useGpu, '--dot_period=10', '--log_period=100')
+    api.initPaddle('--use_gpu=' + useGpu, '--dot_period=10', '--log_period=100', 
+                   '--gpu_id=' + args.gpuId)
     gen_conf = parse_config("gan_conf_image.py", "mode=generator_training,data=" + dataSource)
     dis_conf = parse_config("gan_conf_image.py", "mode=discriminator_training,data=" + dataSource)
     generator_conf = parse_config("gan_conf_image.py", "mode=generator,data=" + dataSource)