Added smoothing eta to fix #280. The previous algorithm could be really jumpy in some cases and has been replaced with an exponential moving average. Double exponential moving average is also available

Author: wolph

examples.py

@@ -644,13 +644,17 @@ def eta_types_demonstration():
         progressbar.Percentage(),
         ' ETA: ',
         progressbar.ETA(),
-        ' Adaptive ETA: ',
+        ' Adaptive : ',
         progressbar.AdaptiveETA(),
-        ' Absolute ETA: ',
+        ' Smoothing(a=0.1): ',
+        progressbar.SmoothingETA(smoothing_parameters=dict(alpha=0.1)),
+        ' Smoothing(a=0.9): ',
+        progressbar.SmoothingETA(smoothing_parameters=dict(alpha=0.9)),
+        ' Absolute: ',
         progressbar.AbsoluteETA(),
-        ' Transfer Speed: ',
+        ' Transfer: ',
         progressbar.FileTransferSpeed(),
-        ' Adaptive Transfer Speed: ',
+        ' Adaptive T: ',
         progressbar.AdaptiveTransferSpeed(),
         ' ',
         progressbar.Bar(),

progressbar/__init__.py

@@ -7,10 +7,12 @@
 from .shortcuts import progressbar
 from .terminal.stream import LineOffsetStreamWrapper
 from .utils import len_color, streams
+from .algorithms import ExponentialMovingAverage, SmoothingAlgorithm, DoubleExponentialMovingAverage
 from .widgets import (
     ETA,
     AbsoluteETA,
     AdaptiveETA,
+    SmoothingETA,
     AdaptiveTransferSpeed,
     AnimatedMarker,
     Bar,
@@ -36,6 +38,7 @@
     Variable,
     VariableMixin,
 )
+from .algorithms import ExponentialMovingAverage, SmoothingAlgorithm
 
 __date__ = str(date.today())
 __all__ = [
@@ -46,6 +49,10 @@
     'ETA',
     'AdaptiveETA',
     'AbsoluteETA',
+    'SmoothingETA',
+    'SmoothingAlgorithm',
+    'ExponentialMovingAverage',
+    'DoubleExponentialMovingAverage',
     'DataSize',
     'FileTransferSpeed',
     'AdaptiveTransferSpeed',

progressbar/bar.py

@@ -776,7 +776,7 @@ def default_widgets(self):
                 ' ',
                 widgets.Timer(**self.widget_kwargs),
                 ' ',
-                widgets.AdaptiveETA(**self.widget_kwargs),
+                widgets.SmoothingETA(**self.widget_kwargs),
             ]
         else:
             return [
@@ -1071,7 +1071,7 @@ def default_widgets(self):
                 ' ',
                 widgets.Timer(),
                 ' ',
-                widgets.AdaptiveETA(),
+                widgets.SmoothingETA(),
             ]
         else:
             return [