Adding a library of methods to calculate perf stats.
Adding a library of methods to calculate various stats from perf
metrics.
The following stats are computed
Kth percentile
Median
Average
Standard Deviation
TEST=None
BUG=None
Change-Id: If5204aba2c1078a52bd49e7e2c8ce8f955bb9036
Reviewed-on: https://chromium-review.googlesource.com/513430
Commit-Ready: Krishna Gavini <krishnargv@chromium.org>
Tested-by: Krishna Gavini <krishnargv@chromium.org>
Reviewed-by: Harpreet Grewal <harpreet@chromium.org>
diff --git a/client/common_lib/cros/perf_stat_lib.py b/client/common_lib/cros/perf_stat_lib.py
new file mode 100644
index 0000000..7c4a71d
--- /dev/null
+++ b/client/common_lib/cros/perf_stat_lib.py
@@ -0,0 +1,74 @@
+# Copyright 2017 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from math import ceil, floor, sqrt
+
+
+def get_kth_percentile(num_list, k):
+ """
+ Computes the k-th percentile of a list of numbers.
+
+ @param num_list: list with numbers.
+ @param k: the percentile to be computed.
+
+ @returns the kth percentile value of the list.
+
+ """
+ if not num_list:
+ return 0
+ assert k >= 0 and k <= 1
+ i = k * (len(num_list) - 1)
+ c, f = int(ceil(i)), int(floor(i))
+ if c == f:
+ return num_list[c]
+ return round((i - f) * num_list[c] + (c - i) * num_list[f], 2)
+
+
+def get_median(num_list):
+ """
+ Computes the median of a list of numbers.
+
+ @param num_list: a list with numbers.
+
+ @returns the median value of the numbers.
+
+ """
+ if not num_list:
+ return 0
+ num_list.sort()
+ size = len(num_list)
+ if size % 2 != 0:
+ return num_list[size / 2]
+ return round((num_list[size / 2] + num_list[size / 2 - 1]) / 2.0, 2)
+
+
+def get_average(num_list):
+ """
+ Computes mean of a list of numbers.
+
+ @param num_list: a list with numbers.
+
+ @returns the average value computed from the list of numbers.
+
+ """
+ if not num_list:
+ return 0
+ return round(float(sum(num_list)) / len(num_list) , 2)
+
+
+def get_std_dev(num_list):
+ """
+ Computes standard deviation of a list of numbers.
+
+ @param num_list: a list with numbers.
+
+ @returns Standard deviation computed from the list of numbers.
+
+ """
+ n = len(num_list)
+ if not num_list or n == 1:
+ return 0
+ mean = float(sum(num_list)) / n
+ variance = sum([(elem - mean) ** 2 for elem in num_list]) / (n -1)
+ return round(sqrt(variance), 2)
\ No newline at end of file
