func_name support for python 3.0 added in xvg.py (#184)

* fix #183 
* gromacs/fileformats/xvg.py: func_name support for python 3.0 added
* AUTHORS and CHANGES updated

AUTHORS

@@ -58,6 +58,11 @@ year of their first commit. GitHub handle is optional.
 
 - Thomas Heavey (@theavey)
 - Andrej Berg (@andrejberg)
+
+2020
+----
+
+- Yury Polyachenko (@polyachenkoya)
 
 We gratefully acknowledge code fixes contributed by
 @quantifiedcode-bot from Quantified Code https://www.quantifiedcode.com

CHANGES

@@ -2,6 +2,10 @@
  CHANGELOG for GromacsWrapper
 ==============================
 
+2020-xx-xx     0.8.1
+
+* fixed: xvg._decimate used python-2.0-specific func_name()
+
 2019-xx-xx     0.8.1
 orbeckst
 

gromacs/fileformats/xvg.py

@@ -1079,9 +1079,13 @@ def _decimate(self, func, a, maxpoints, **kwargs):
             out[i], out[0] = func(t, a[i], bins=maxpoints, **kwargs)
 
         if maxpoints == self.maxpoints_default:  # only warn if user did not set maxpoints
+            try:
+                funcname = func.func_name    # Python 2
+            except AttributeError:
+                funcname = func.__name__     # Python 3
             warnings.warn("Plot had %d datapoints > maxpoints = %d; decimated to %d regularly "
                           "spaced points from the histogrammed data with %s()."
-                          % (ny, maxpoints, maxpoints, func.func_name),
+                          % (ny, maxpoints, maxpoints, funcname),
                           category=AutoCorrectionWarning)
         return out