Improve presentation of aggregate results in mojo_benchmark.

mojo/devtools/common/mojo_benchmark

 #!/usr/bin/env python
 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Runner for Mojo application benchmarks."""
 
 import argparse
 import logging
+import numpy
 import sys
 import time
 
 from devtoolslib import benchmark
 from devtoolslib import perf_dashboard
 from devtoolslib import shell_arguments
 from devtoolslib import shell_config
 
 
 _DESCRIPTION = """Runner for Mojo application benchmarks.
@@ skipping 43 matching lines @@
   if not outcome.succeeded:
     print 'benchmark failed: ' + outcome.error_str
   if outcome.some_measurements_failed:
     print 'some measurements failed'
   print 'output: '
   print '-' * 72
   print outcome.output
   print '-' * 72
 
 
+def _format_vector(results):
+  if not len(results):
+    return "med -, avg -, std-dev -, (no results)"
+
+  return "med %f, avg %f, std-dev %f %s" % (numpy.median(results),
+                                                numpy.mean(results),
+                                                numpy.std(results),
+                                                str(results))
+
+
 def _print_results(benchmark_name, variant_name, results, measurements,
                    aggregate):
   print '[ %s ] %s ' % (benchmark_name, variant_name)
   for measurement in measurements:
     print '  ' + measurement['name'] + ': ',
     if measurement['spec'] in results:
       if aggregate:
-        print str(results[measurement['spec']])
+        print _format_vector(results[measurement['spec']])
       else:
         if len(results[measurement['spec']]) == 0:
           print '?'
         else:
           print '%f' % results[measurement['spec']][0]
     else:
       print '?'
 
 
 def _upload_results(benchmark_name, variant_name, results, measurements,
@@ skipping 120 matching lines @@
                                            variant_results[variant_name],
                                            variant_spec['measurements'],
                                            script_args)
         if not upload_succeeded:
           exit_code = 1
 
   return exit_code
 
 if __name__ == '__main__':
   sys.exit(main())