Skip to content
Projects
Groups
Snippets
Help
Loading...
Help
Support
Keyboard shortcuts
?
Submit feedback
Contribute to GitLab
Sign in / Register
Toggle navigation
C
cpython
Project overview
Project overview
Details
Activity
Releases
Repository
Repository
Files
Commits
Branches
Tags
Contributors
Graph
Compare
Issues
0
Issues
0
List
Boards
Labels
Milestones
Merge Requests
0
Merge Requests
0
Analytics
Analytics
Repository
Value Stream
Wiki
Wiki
Members
Members
Collapse sidebar
Close sidebar
Activity
Graph
Create a new issue
Commits
Issue Boards
Open sidebar
Kirill Smelkov
cpython
Commits
63d15223
Commit
63d15223
authored
Dec 24, 2018
by
leodema
Committed by
Raymond Hettinger
Dec 23, 2018
Browse files
Options
Browse Files
Download
Email Patches
Plain Diff
bpo-30561: Sync-up expovariate() and gammavariate code (GH-1934)
parent
b7105c9c
Changes
3
Hide whitespace changes
Inline
Side-by-side
Showing
3 changed files
with
36 additions
and
15 deletions
+36
-15
Lib/random.py
Lib/random.py
+1
-4
Lib/test/test_random.py
Lib/test/test_random.py
+31
-11
Misc/NEWS.d/next/Library/2018-12-23-22-27-59.bpo-30561.PSRQ2w.rst
...S.d/next/Library/2018-12-23-22-27-59.bpo-30561.PSRQ2w.rst
+4
-0
No files found.
Lib/random.py
View file @
63d15223
...
...
@@ -582,10 +582,7 @@ class Random(_random.Random):
elif
alpha
==
1.0
:
# expovariate(1/beta)
u
=
random
()
while
u
<=
1e-7
:
u
=
random
()
return
-
_log
(
u
)
*
beta
return
-
_log
(
1.0
-
random
())
*
beta
else
:
# alpha is between 0 and 1 (exclusive)
...
...
Lib/test/test_random.py
View file @
63d15223
...
...
@@ -853,28 +853,48 @@ class TestDistributions(unittest.TestCase):
self
.
assertRaises
(
ValueError
,
random
.
gammavariate
,
2
,
0
)
self
.
assertRaises
(
ValueError
,
random
.
gammavariate
,
1
,
-
3
)
# There are three different possibilities in the current implementation
# of random.gammavariate(), depending on the value of 'alpha'. What we
# are going to do here is to fix the values returned by random() to
# generate test cases that provide 100% line coverage of the method.
@
unittest
.
mock
.
patch
(
'random.Random.random'
)
def
test_gammavariate_full_code_coverage
(
self
,
random_mock
):
# There are three different possibilities in the current implementation
# of random.gammavariate(), depending on the value of 'alpha'. What we
# are going to do here is to fix the values returned by random() to
# generate test cases that provide 100% line coverage of the method.
def
test_gammavariate_alpha_greater_one
(
self
,
random_mock
):
# #1: alpha > 1.0: we want the first random number to be outside the
# #1: alpha > 1.0.
# We want the first random number to be outside the
# [1e-7, .9999999] range, so that the continue statement executes
# once. The values of u1 and u2 will be 0.5 and 0.3, respectively.
random_mock
.
side_effect
=
[
1e-8
,
0.5
,
0.3
]
returned_value
=
random
.
gammavariate
(
1.1
,
2.3
)
self
.
assertAlmostEqual
(
returned_value
,
2.53
)
# #2: alpha == 1: first random number less than 1e-7 to that the body
# of the while loop executes once. Then random.random() returns 0.45,
@
unittest
.
mock
.
patch
(
'random.Random.random'
)
def
test_gammavariate_alpha_equal_one
(
self
,
random_mock
):
# #2.a: alpha == 1.
# The execution body of the while loop executes once.
# Then random.random() returns 0.45,
# which causes while to stop looping and the algorithm to terminate.
random_mock
.
side_effect
=
[
1e-8
,
0.45
]
random_mock
.
side_effect
=
[
0.45
]
returned_value
=
random
.
gammavariate
(
1.0
,
3.14
)
self
.
assertAlmostEqual
(
returned_value
,
2.507314166123803
)
self
.
assertAlmostEqual
(
returned_value
,
1.877208182372648
)
@
unittest
.
mock
.
patch
(
'random.Random.random'
)
def
test_gammavariate_alpha_equal_one_equals_expovariate
(
self
,
random_mock
):
# #2.b: alpha == 1.
# It must be equivalent of calling expovariate(1.0 / beta).
beta
=
3.14
random_mock
.
side_effect
=
[
1e-8
,
1e-8
]
gammavariate_returned_value
=
random
.
gammavariate
(
1.0
,
beta
)
expovariate_returned_value
=
random
.
expovariate
(
1.0
/
beta
)
self
.
assertAlmostEqual
(
gammavariate_returned_value
,
expovariate_returned_value
)
@
unittest
.
mock
.
patch
(
'random.Random.random'
)
def
test_gammavariate_alpha_between_zero_and_one
(
self
,
random_mock
):
# #3: 0 < alpha < 1. This is the most complex region of code to cover,
# #3: 0 < alpha < 1.
# This is the most complex region of code to cover,
# as there are multiple if-else statements. Let's take a look at the
# source code, and determine the values that we need accordingly:
#
...
...
Misc/NEWS.d/next/Library/2018-12-23-22-27-59.bpo-30561.PSRQ2w.rst
0 → 100644
View file @
63d15223
random.gammavariate(1.0, beta) now computes the same result as
random.expovariate(1.0 / beta). This synchonizes the two algorithms and
eliminates some idiosyncrasies in the old implementation. It does however
produce a difference stream of random variables than it used to.
Write
Preview
Markdown
is supported
0%
Try again
or
attach a new file
Attach a file
Cancel
You are about to add
0
people
to the discussion. Proceed with caution.
Finish editing this message first!
Cancel
Please
register
or
sign in
to comment