[
https://issues.apache.org/jira/browse/PIG-3926?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Philip (flip) Kromer reopened PIG-3926:
---------------------------------------
* ROUND_TO returns NULL given a NULL value (rather than failing)
* It now by default rounds to the nearest neighbor, choosing the _even_ digit
for ties: ROUND_TO(-2.5,1) == -2.0, ROUND_TO(-1.5,1) == -2.0. See
http://docs.oracle.com/javase/7/docs/api/java/math/RoundingMode.html#HALF_EVEN:
"This is the rounding mode that statistically minimizes cumulative error when
applied repeatedly over a sequence of calculations [... and] is analogous to
the rounding policy used for float and double arithmetic in Java"
* You can specify the rounding mode using an optional third parameter,
supplying the integer value of one of the rounding modes:
http://docs.oracle.com/javase/7/docs/api/constant-values.html#java.math
* Added more test cases.
> ROUND_TO function: rounds double/float to fixed number of decimal places
> ------------------------------------------------------------------------
>
> Key: PIG-3926
> URL: https://issues.apache.org/jira/browse/PIG-3926
> Project: Pig
> Issue Type: New Feature
> Affects Versions: 0.12.0
> Reporter: Philip (flip) Kromer
> Assignee: Philip (flip) Kromer
> Priority: Minor
> Labels: builtin, function, math
> Fix For: 0.13.0
>
> Attachments: 0001-ROUND_TO-handles-nulls-accepts-rounding-mode.patch,
> 0001-Unit-tests-for-ROUND.patch,
> 0002-ROUND_TO-UDF-safely-rounds-values-to-given-precision.patch
>
>
> The too-often used trick of rounding to a fixed number of decimal places by
> writing '1000 * Math.round(num / 1000.0)' is not only unsightly, it's
> numerically imprecise (http://stackoverflow.com/a/12684082/41857). The
> attached patch adds a function to do this.
> ROUND_TO(val, digits) accepts a single float or double value, along with an
> integer number of digits, and returns the value to that number of decimal
> places
> Examples:
> {code}
> ROUND_TO(3.14159f, 3) -- returns a float 3.142
> ROUND_TO(3.14159d, 0) -- returns a double 3.0.
> {code}
> I also added unit tests for ROUND -- there were none before that I could find.
> I don't know how to write a unit test that the schema correctly routes to
> FloatRoundTo and DoubleRoundTo -- if the ones I provided are insufficient
> please point me to a simple example to emulate.
--
This message was sent by Atlassian JIRA
(v6.2#6252)
