Telemetry: Don't use scientific notation for floats when printing results.

When parsing results for the dashboard we don't expect any letters (such as the
'e' in scientific notation) in the string of values. This CL makes sure we don't
use scientific notation for printing floats.

BUG=318093

Review URL: https://codereview.chromium.org/71543002

git-svn-id: http://src.chromium.org/svn/trunk/src/build@234829 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

util/lib/common/perf_tests_results_helper.py

@@ -63,18 +63,26 @@ def GeomMeanAndStdDevFromHistogram(histogram_json):
   return geom_mean, math.sqrt(sum_of_squares / count)
 
 
+def _ValueToString(v):
+  # Special case for floats so we don't print using scientific notation.
+  if isinstance(v, float):
+    return '%f' % v
+  else:
+    return str(v)
+
+
 def _MeanAndStdDevFromList(values):
   avg = None
   sd = None
   if len(values) > 1:
     try:
-      value = '[%s]' % ','.join([str(v) for v in values])
+      value = '[%s]' % ','.join([_ValueToString(v) for v in values])
       avg = sum([float(v) for v in values]) / len(values)
       sqdiffs = [(float(v) - avg) ** 2 for v in values]
       variance = sum(sqdiffs) / (len(values) - 1)
       sd = math.sqrt(variance)
     except ValueError:
-      value = ", ".join(values)
+      value = ', '.join(values)
   else:
     value = values[0]
   return value, avg, sd