add python version check for visualdl (#952)

docs/tutorials/GETTING_STARTED.md

@@ -41,8 +41,8 @@ list below can be viewed by `--help`
 |    --draw_threshold      |      infer     |  Threshold to reserve the result for visualization  |  0.5  |  `--draw_threshold 0.7`  |
 |      --infer_dir         |       infer     |  Directory for images to perform inference on  |  None  |    |
 |      --infer_img         |       infer     |  Image path  |  None  |  higher priority over --infer_dir  |
-|        --use_vdl          |   train/infer   |  Whether to record the data with [VisualDL](https://github.com/paddlepaddle/visualdl), so as to display in VisualDL  |  False  |      |
-|        --vdl\_log_dir     |   train/infer   |  VisualDL logging directory for image  |  train:`vdl_log_dir/scalar` infer: `vdl_log_dir/image`  |     |
+|        --use_vdl          |   train/infer   |  Whether to record the data with [VisualDL](https://github.com/paddlepaddle/visualdl), so as to display in VisualDL  |  False  |  VisualDL requires Python>=3.5   |
+|        --vdl\_log_dir     |   train/infer   |  VisualDL logging directory for image  |  train:`vdl_log_dir/scalar` infer: `vdl_log_dir/image`  |  VisualDL requires Python>=3.5   |
 
 
 ## Examples

docs/tutorials/GETTING_STARTED_cn.md

@@ -38,8 +38,8 @@ python tools/infer.py -c configs/faster_rcnn_r50_1x.yml --infer_img=demo/0000005
 |    --draw_threshold      |      infer     |  可视化时分数阈值  |  0.5  |  `--draw_threshold 0.7`  |
 |      --infer_dir         |       infer     |  用于预测的图片文件夹路径  |  None  |    |
 |      --infer_img         |       infer     |  用于预测的图片路径  |  None  |  相较于`--infer_dir`具有更高优先级  |
-|        --use_vdl          |   train/infer   |  是否使用[VisualDL](https://github.com/paddlepaddle/visualdl)记录数据，进而在VisualDL面板中显示  |  False  |      |
-|        --vdl\_log_dir     |   train/infer   |  指定 VisualDL 记录数据的存储路径  |  train:`vdl_log_dir/scalar` infer: `vdl_log_dir/image`  |     |
+|        --use_vdl          |   train/infer   |  是否使用[VisualDL](https://github.com/paddlepaddle/visualdl)记录数据，进而在VisualDL面板中显示  |  False  |  VisualDL需Python>=3.5    |
+|        --vdl\_log_dir     |   train/infer   |  指定 VisualDL 记录数据的存储路径  |  train:`vdl_log_dir/scalar` infer: `vdl_log_dir/image`  |  VisualDL需Python>=3.5   |
 
 
 ## 使用示例

tools/infer.py

@@ -24,6 +24,7 @@ if parent_path not in sys.path:
 
 import glob
 import numpy as np
+import six
 from PIL import Image
 
 from paddle import fluid
@@ -160,6 +161,7 @@ def main():
 
     # use VisualDL to log image
     if FLAGS.use_vdl:
+        assert six.PY3, "VisualDL requires Python >= 3.5"
         from visualdl import LogWriter
         vdl_writer = LogWriter(FLAGS.vdl_log_dir)
         vdl_image_step = 0

tools/train.py

@@ -26,6 +26,7 @@ import time
 import numpy as np
 import random
 import datetime
+import six
 from collections import deque
 from paddle.fluid import profiler
 
@@ -224,6 +225,7 @@ def main():
 
     # use VisualDL to log data
     if FLAGS.use_vdl:
+        assert six.PY3, "VisualDL requires Python >= 3.5"
         from visualdl import LogWriter
         vdl_writer = LogWriter(FLAGS.vdl_log_dir)
         vdl_loss_step = 0