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https://issues.apache.org/jira/browse/MATH-1130?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Venkatesha Murthy TS updated MATH-1130:
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Attachment: math-1130.patch
Added replace and remove methods into MathArrays. these have two flavours one
with full array and another flavour with (values, begin, length) just to be
consistent with verifyValues and copyOf where length is a parameter. I am
willing to change to make use of start and end indices but felt that signature
in verifyValues seemed more natural for me and hence continued the same
tradition even to these methods. (For eg: copyOf, verifyValues,
System.arraycopy where a start index/indices and a length is good to drive)
Added a canEqual method into MathUtils and have added testEquals and
testCanEqual to indicate canEqual runs faster. if you closely observe in
testEquals i have reduced the for loop iteration counts as otherwise if we made
the same numbers as that of testCanEqual it would take very long time.I have
also tried with Precision.equalsIncludingNan but without much a success in
speed. I just added these high iteration counts to verify why canEqual may be
better.
So either we could go with adding this new method
or alter MathUtils.equals or Precision.equasIncludingNaN methods.
Please let me know your thoughts
> A new set of functions for copyof, remove and replace a given value on a
> slice of array
> ---------------------------------------------------------------------------------------
>
> Key: MATH-1130
> URL: https://issues.apache.org/jira/browse/MATH-1130
> Project: Commons Math
> Issue Type: New Feature
> Affects Versions: 3.4
> Reporter: Venkatesha Murthy TS
> Attachments: math-1130.patch
>
>
> These are utility functions mostly required as part of MathArrays.
> MathArrays:
> =============
> The requirement is as follows:
> a) double[] copyOf(double[] values, int begin, int length) ;
> Similar to most other functions that support slice defined by the array
> part from [begin, begin+length) ;its a requirement to copy a slice which is
> not available (the closest is copyOf(array, int len) which misses out the
> begin index)
> b) double[] removeAll(double[] values, int begin, int length, double
> removable);
> Need a function to remove a value from array slice defined by
> [begin,begin+length) and return the filtered version.
> c) double[] replaceAll(double[] values, int begin, int length, double
> oldValue, double newValue);
> Need a function to replace inplace an oldValue substituted with newValue in
> the array slice defined by [begin,begin+length) and return the original
> complete array with just replaced values only in the segment
> [begin,begin+length)
> MathUtils
> =========
> boolean canEqual(double d1, double d2) ;
> provide a canEqual function that is slightly better than exisitng
> MathUtils.equals. We could also improve existing equals method however.
> So the change here is that the new enhanced canEqual can do a quick check on
> Nans and as well as both +ve and -ve Infinities faster and then move to a
> detailed Double.compare(..) method. This avoids the Double.compare call for
> infinities and NaN with faster reference equal check (i.e == ).
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