[jira] [Commented] (LUCENE-4148) _TestUtil should be able to generate random longs
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https://issues.apache.org/jira/browse/LUCENE-4148?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13395487#comment-13395487
]
Dawid Weiss commented on LUCENE-4148:
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I didn't check _TestUtil, to be honest -- I think it did have a bug with range
overflow passed to nextInt (which is not a problem in practice, but was my
example on how randomized testing can explore unexpected things).
Anyway, as for randomLongBetween -- here you'd need to be more careful about
double's representation so simple scaling won't work (there are ranges of
double that transform to NaNs for example). I am not so strong in numerical
analysis to be able to prove something is a correct solution to the problem. My
(naive) take at this would be to calculate the range and then if split into a
few cases:
1) if it doesn't exceed a positive int, use nextInt()
2) if it doesn't exceed a positive long, use nextLong()
3) if it does exceed positive long, use BigDecimal? :)
Maybe this can be done faster without keeping the uniform distribution
requirement so strong (i.e. use a modulo from a combination of two concatenated
longs as BigDecimal or something like that).
_TestUtil should be able to generate random longs
-
Key: LUCENE-4148
URL: https://issues.apache.org/jira/browse/LUCENE-4148
Project: Lucene - Java
Issue Type: Improvement
Components: general/test
Reporter: Adrien Grand
Priority: Trivial
It would be helpful in TestPackedInts at least, in order to generate random
values (as a workaround, we currently generate a random int between 0 and
{{min(Integer.MAX_VALUE, PackedInts.maxValue(bitsPerValue)}}). Moreover, it
would help to fix {{nextInt}} for large ranges (calling {{nextInt(random,
-10, Integer.MAX_VALUE)}} or even {{nextInt(random, 0, Integer.MAX_VALUE)}}
currently fails because the range of values is {{ Integer.MAX_VALUE}}.
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[jira] [Commented] (LUCENE-4148) _TestUtil should be able to generate random longs
[
https://issues.apache.org/jira/browse/LUCENE-4148?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13395992#comment-13395992
]
Dawid Weiss commented on LUCENE-4148:
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This looks good to me, although I'm wondering how much randomness do we really
need -- those BigIntegers are worrying. I think this can be improved later if
somebody wishes to dive into it.
Btw. an interesting random number generator --
_TestUtil should be able to generate random longs
-
Key: LUCENE-4148
URL: https://issues.apache.org/jira/browse/LUCENE-4148
Project: Lucene - Java
Issue Type: Improvement
Components: general/test
Reporter: Adrien Grand
Priority: Trivial
Attachments: LUCENE-4148.patch
It would be helpful in TestPackedInts at least, in order to generate random
values (as a workaround, we currently generate a random int between 0 and
{{min(Integer.MAX_VALUE, PackedInts.maxValue(bitsPerValue)}}). Moreover, it
would help to fix {{nextInt}} for large ranges (calling {{nextInt(random,
-10, Integer.MAX_VALUE)}} or even {{nextInt(random, 0, Integer.MAX_VALUE)}}
currently fails because the range of values is {{ Integer.MAX_VALUE}}.
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[jira] [Commented] (LUCENE-4148) _TestUtil should be able to generate random longs
[
https://issues.apache.org/jira/browse/LUCENE-4148?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13393632#comment-13393632
]
Adrien Grand commented on LUCENE-4148:
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It seems to me that {{min}} and {{max}} are inclusive in both methods.
@Dawid could RandomInts have a similar method to generate longs? Something like
{code}
public static long randomLongBetween(Random r, long min, long max);
{code}
_TestUtil should be able to generate random longs
-
Key: LUCENE-4148
URL: https://issues.apache.org/jira/browse/LUCENE-4148
Project: Lucene - Java
Issue Type: Improvement
Components: general/test
Reporter: Adrien Grand
Priority: Trivial
It would be helpful in TestPackedInts at least, in order to generate random
values (as a workaround, we currently generate a random int between 0 and
{{min(Integer.MAX_VALUE, PackedInts.maxValue(bitsPerValue)}}). Moreover, it
would help to fix {{nextInt}} for large ranges (calling {{nextInt(random,
-10, Integer.MAX_VALUE)}} or even {{nextInt(random, 0, Integer.MAX_VALUE)}}
currently fails because the range of values is {{ Integer.MAX_VALUE}}.
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[jira] [Commented] (LUCENE-4148) _TestUtil should be able to generate random longs
[
https://issues.apache.org/jira/browse/LUCENE-4148?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13295713#comment-13295713
]
Dawid Weiss commented on LUCENE-4148:
-
Try RandomInts from randomizedtesting, it does what you need:
{code}
/**
* A random integer from codemin/code to codemax/code (inclusive).
*/
public static int randomIntBetween(Random r, int min, int max) {
assert max = min : max must be = min: + min + , + max;
long range = (long) max - (long) min;
if (range Integer.MAX_VALUE) {
return min + r.nextInt(1 + (int) range);
} else {
return min + (int) Math.round(r.nextDouble() * range);
}
}
{code}
_TestUtil should be able to generate random longs
-
Key: LUCENE-4148
URL: https://issues.apache.org/jira/browse/LUCENE-4148
Project: Lucene - Java
Issue Type: Improvement
Components: general/test
Reporter: Adrien Grand
Priority: Trivial
It would be helpful in TestPackedInts at least, in order to generate random
values (as a workaround, we currently generate a random int between 0 and
{{min(Integer.MAX_VALUE, PackedInts.maxValue(bitsPerValue)}}). Moreover, it
would help to fix {{nextInt}} for large ranges (calling {{nextInt(random,
-10, Integer.MAX_VALUE)}} or even {{nextInt(random, 0, Integer.MAX_VALUE)}}
currently fails because the range of values is {{ Integer.MAX_VALUE}}.
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[jira] [Commented] (LUCENE-4148) _TestUtil should be able to generate random longs
[
https://issues.apache.org/jira/browse/LUCENE-4148?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13295715#comment-13295715
]
Robert Muir commented on LUCENE-4148:
-
can we just switch _TestUtil.nextInt to use this then?
_TestUtil should be able to generate random longs
-
Key: LUCENE-4148
URL: https://issues.apache.org/jira/browse/LUCENE-4148
Project: Lucene - Java
Issue Type: Improvement
Components: general/test
Reporter: Adrien Grand
Priority: Trivial
It would be helpful in TestPackedInts at least, in order to generate random
values (as a workaround, we currently generate a random int between 0 and
{{min(Integer.MAX_VALUE, PackedInts.maxValue(bitsPerValue)}}). Moreover, it
would help to fix {{nextInt}} for large ranges (calling {{nextInt(random,
-10, Integer.MAX_VALUE)}} or even {{nextInt(random, 0, Integer.MAX_VALUE)}}
currently fails because the range of values is {{ Integer.MAX_VALUE}}.
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[jira] [Commented] (LUCENE-4148) _TestUtil should be able to generate random longs
[
https://issues.apache.org/jira/browse/LUCENE-4148?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13295720#comment-13295720
]
Adrien Grand commented on LUCENE-4148:
--
bq. Try RandomInts from randomizedtesting
Thanks, it fixes the problem for large range of ints, but I would also like to
be able to generate random longs ( Integer.MAX_VALUE) in a fixed range. For
{{PackedInts}}, I always need longs between 0 and a power of 2, but I thought
it would be more useful to add a general-purpose {{long nextLong(Random, long,
long)}} to {{_TestUtil}}.
Since {{Random.nextLong(long)}} doesn't exist, it would be tempting to
implement it by ourselves by using the same logic as {{Random.nextInt(int)}},
but I am afraid there would be copyright issues, so we should probably do it
otherwise (?).
By the way, the code of {{randomIntBetween}} makes me curious, are all values
as likely when the range of values is {{= Integer.MAX_VALUE}} (ie. when the
else block gets executed)?
_TestUtil should be able to generate random longs
-
Key: LUCENE-4148
URL: https://issues.apache.org/jira/browse/LUCENE-4148
Project: Lucene - Java
Issue Type: Improvement
Components: general/test
Reporter: Adrien Grand
Priority: Trivial
It would be helpful in TestPackedInts at least, in order to generate random
values (as a workaround, we currently generate a random int between 0 and
{{min(Integer.MAX_VALUE, PackedInts.maxValue(bitsPerValue)}}). Moreover, it
would help to fix {{nextInt}} for large ranges (calling {{nextInt(random,
-10, Integer.MAX_VALUE)}} or even {{nextInt(random, 0, Integer.MAX_VALUE)}}
currently fails because the range of values is {{ Integer.MAX_VALUE}}.
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[jira] [Commented] (LUCENE-4148) _TestUtil should be able to generate random longs
[
https://issues.apache.org/jira/browse/LUCENE-4148?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13295765#comment-13295765
]
Dawid Weiss commented on LUCENE-4148:
-
@Robert: sure we could (noting the subtle difference that the range is
inclusive on both min and max).
As for distribution... I think it should be uniform over all of the range's
values assuming r.nextDouble() yields uniform value from [0,1]? It's simple
scaling after all. I didn't really consider nuances of floating point
representation here but I think within 2^32 a double should cover everything
fairly well.
_TestUtil should be able to generate random longs
-
Key: LUCENE-4148
URL: https://issues.apache.org/jira/browse/LUCENE-4148
Project: Lucene - Java
Issue Type: Improvement
Components: general/test
Reporter: Adrien Grand
Priority: Trivial
It would be helpful in TestPackedInts at least, in order to generate random
values (as a workaround, we currently generate a random int between 0 and
{{min(Integer.MAX_VALUE, PackedInts.maxValue(bitsPerValue)}}). Moreover, it
would help to fix {{nextInt}} for large ranges (calling {{nextInt(random,
-10, Integer.MAX_VALUE)}} or even {{nextInt(random, 0, Integer.MAX_VALUE)}}
currently fails because the range of values is {{ Integer.MAX_VALUE}}.
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