Re: [math] Mean, Median but no Mode?

[sebb <se...@gmail.com>]

On 4 July 2013 16:46, William Speirs <ws...@apache.org> wrote:
> The Frequency[1] class is what you're looking for. You can find a basic
> example of it in the user guide [2].

Perhaps the docs should include "mode" as an example as well?
Or maybe it should be added to the Frequency class? (and StatUtils)

AFAICT the only way to get the mode is to scan all the entries looking
for the the maximum count, caching the value(s) on the way.
This is not completely trivial.

> Bill-
>
> [1]
> http://commons.apache.org/proper/commons-math/apidocs/org/apache/commons/math3/stat/Frequency.html
> [2]
> http://commons.apache.org/proper/commons-math/userguide/stat.html#a1.3_Frequency_distributions
>
>
> On Thu, Jul 4, 2013 at 11:29 AM, Matt Benson <gu...@gmail.com> wrote:
>
>> I don't know about [math], but [lang] 3.x has mean, median and mode in
>> ObjectUtils.
>>
>> Matt
>> On Jul 4, 2013 10:25 AM, "Ben Titmarsh" <be...@hotmail.co.uk>
>> wrote:
>>
>> > Hi,
>> >
>> > I am looking for a library that can provide the mode (
>> > http://en.wikipedia.org/wiki/Mode_%28statistics%29) of a set numbers.
>> > This is a simple arithmetic operation but I am unable to find a reference
>> > to this in the documentation.  Can anyone point it out to me, if not
>> > suggest why it is not supported?
>> >
>> > Thanks,
>> > Ben.
>> >
>>

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Re: [math] Mean, Median but no Mode?

[Phil Steitz <ph...@gmail.com>]

On 7/4/13 9:26 AM, sebb wrote:
> On 4 July 2013 16:46, William Speirs <ws...@apache.org> wrote:
>> The Frequency[1] class is what you're looking for. You can find a basic
>> example of it in the user guide [2].
> Perhaps the docs should include "mode" as an example as well?
> Or maybe it should be added to the Frequency class? (and StatUtils)
>
> AFAICT the only way to get the mode is to scan all the entries looking
> for the the maximum count, caching the value(s) on the way.
> This is not completely trivial.

Right.  That is what Frequency does, essentially.  It would make
sense to add a method to Frequency returning a collection or
double[] (since mode is not well-defined - i.e., there can be
several equiprobable maxima of the pmf).  Then add a convenience
method (possibly multiple, for different input data types) to
StatUtils that uses this.

Might also make sense to add mode as a (single-valued) property of
IntegerDistribution.  Will be NaN sometimes, but same is true of
mean and variance.

Patches welcome!

Phil




>
>> Bill-
>>
>> [1]
>> http://commons.apache.org/proper/commons-math/apidocs/org/apache/commons/math3/stat/Frequency.html
>> [2]
>> http://commons.apache.org/proper/commons-math/userguide/stat.html#a1.3_Frequency_distributions
>>
>>
>> On Thu, Jul 4, 2013 at 11:29 AM, Matt Benson <gu...@gmail.com> wrote:
>>
>>> I don't know about [math], but [lang] 3.x has mean, median and mode in
>>> ObjectUtils.
>>>
>>> Matt
>>> On Jul 4, 2013 10:25 AM, "Ben Titmarsh" <be...@hotmail.co.uk>
>>> wrote:
>>>
>>>> Hi,
>>>>
>>>> I am looking for a library that can provide the mode (
>>>> http://en.wikipedia.org/wiki/Mode_%28statistics%29) of a set numbers.
>>>> This is a simple arithmetic operation but I am unable to find a reference
>>>> to this in the documentation.  Can anyone point it out to me, if not
>>>> suggest why it is not supported?
>>>>
>>>> Thanks,
>>>> Ben.
>>>>
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>


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