Merge pull request #5283 from will-am/plot_to_file

Support saving figure to file

Author: pengli09

python/paddle/v2/plot/plot.py

@@ -56,7 +56,7 @@ def append(self, title, step, value):
         assert isinstance(data, PlotData)
         data.append(step, value)
 
-    def plot(self):
+    def plot(self, path=None):
         if self.__plot_is_disabled__():
             return
 
@@ -68,8 +68,11 @@ def plot(self):
                 titles.append(title)
                 self.plt.plot(data.step, data.value)
         self.plt.legend(titles, loc='upper left')
-        self.display.clear_output(wait=True)
-        self.display.display(self.plt.gcf())
+        if path is None:
+            self.display.clear_output(wait=True)
+            self.display.display(self.plt.gcf())
+        else:
+            self.plt.savefig(path)
         self.plt.gcf().clear()
 
     def reset(self):