[Insight-users] itkHistogram with double, comments

Fri May 20 09:00:53 EDT 2005

For goodness of fit computations and other histogram convolution/matching  
functions we need to support non-integer frequency counts

Stephen

___
Stephen R. Aylward, Ph.D.
Associate Professor
Computer-Aided Diagnosis & Display Lab (CADDLab)
http://caddlab.rad.unc.edu

...... Original Message .......
On Fri, 20 May 2005 08:39:22 -0400 "Miller, James V (Research)" 
<millerjv at crd.ge.com> wrote:
>Michal,
>
>Would storing the frequency in double address your standard use cases?
>
>Or should we be investigating storing storing counts in an in integral type
>(perhaps up to a long long if necessary).
>
>Jim
>
>
>
>-----Original Message-----
>From: Michal Sofka [mailto:sofka at cs.rpi.edu]
>Sent: Thursday, May 19, 2005 9:56 PM
>To: Miller, James V (Research)
>Cc: Stephen R. Aylward; Michal Sofka; insight-users at itk.org
>Subject: RE: [Insight-users] itkHistogram with double, comments
>
>
>
>One additional consideration -- it would be good if we don't force the 
>histogram's frequency type to be float only. This might cause problems 
>with large histograms. For example when the total frequency is more than 
>1e+7, than increasing frequency by 1 (in any bin) does not change total 
>frequency member variable (because of lack of precision). I've tried this 
>case and there are ways around it but it would be nice if it works in 
>general.
>
>
>Michal.
>
>
>
>> I think this is similar to other arguments.  You are basically
>> saying that GetFrequency/GetTotalFrequency always return double
>> regardless of how the frequency is stored in the FrequencyContainer.
>>
>>
>> Jim
>>
>>
>> -----Original Message-----
>> From: Stephen R. Aylward [mailto:aylward at unc.edu]
>> Sent: Thursday, May 19, 2005 4:35 PM
>> To: Miller, James V (Research)
>> Cc: Michal Sofka; insight-users at itk.org
>> Subject: Re: [Insight-users] itkHistogram with double, comments
>>
>>
>>
>> GetFrequency and GetTotalFrequency are pure virtual functions in the
>> class Sample.
>>
>> Why not have those functions return double, do away with the concept of
>> FrequencyType in the Sample class, and let the subclasses instantiate
>> FrequencyType as they see fit?
>>
>> Stephen
>>
>>
>> Miller, James V (Research) wrote:
>>> Michal,
>>>
>>> Thanks for pointing this out.
>>>
>>> For #1, I am not sure how we want to fix it.
>>>
>>> a) Make Sample templated over frequency type.  Then Histogram can define
>>> its superclass based by extracting the frequency type from the 
FrequencyContainer
>>> that the histogram is templated over. I don't really like this approach 
because
>>> I hate having to add a template parameter to such a base class.  But the
>>> template parameter in the base class could default to float, minimizing 
the
>>> impact to backward compatibility.
>>>
>>> b) Histogram could define its FrequencyType from its superclass and 
accept any
>>> change in precision when communicating with the FrequencyContainer. I 
don't like
>>> this approach because it potentially hides a loss in precision and 
requires
>>> casting at every GetFrequency() call.
>>>
>>> c) Change the FrequencyContainers to NOT be templated over frequency 
type
>>> and just define FrequencyType to ALWAYS be float.  I don't like this
>>> because existing code will no longer compile.
>>>
>>> d) Use ConceptChecking so that Histogram can only use 
FrequencyContainers that
>>> are use floats as the FrequencyType.  All this buys us from the current 
situation
>>> is a potentially clearer compiler error.
>>>
>>> As you can tell, I am not particularly happy with any of these solutions.  Perhaps
>>> another developer may have another idea.
>>>
>>> I fixed the documentation errors you indicated.
>>>
>>> Jim
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: insight-users-bounces+millerjv=crd.ge.com at itk.org
>>> [mailto:insight-users-bounces+millerjv=crd.ge.com at itk.org]On Behalf Of
>>> Michal Sofka
>>> Sent: Thursday, May 19, 2005 1:54 PM
>>> To: insight-users at itk.org
>>> Subject: [Insight-users] itkHistogram with double, comments
>>>
>>>
>>>
>>> Hi itk users (and developers),
>>>
>>> I've been using itkHistogram and found several inconsistencies:
>>>
>>> 1. It is derived from itkSample, that has
>>>   typedef float FrequencyType ;
>>> but the Histogram itself is templated over FrequencyType (through
>>> TFrequencyContainer). As a result, when instantiating with a different 
type
>>> for TFrequencyContainer than float, there are conflicts in GetFrequency 
and
>>> GetTotalFrequency return types (see error messages below). (I'm using 
VS7.0,
>>> Win2000.)
>>>
>>> 2. Comments for IncreaseFrequency functions (all prototypes) is not 
right
>>> /** Method to increase the frequency by one.  This function is 
convenient
>>>     to create a histogram. It returns false if the bin is out of 
bounds. */
>>> It increases the frequency by 'value'.
>>>
>>> 3. Comment before the class (in the header file, line 46) is not right:
>>>  * After this, users want to set range of each bin using
>>>  * SetBinMin(dimension, n) and SetBinMax(dimension, n) methods.
>>> The prototype of these functions is different.
>>>
>>>
>>> Thanks.
>>>
>>> Michal.
>>>
>>>
>>>
>>> -----------------------------------
>>> Michal Sofka, PhD student
>>> Department of Computer Science, RPI
>>> sofka at cs.rpi.edu
>>>
>>>
>>>
>>>
>>> Issue 1 errors:
>>>
>>> itkHistogram.h(231) : error C2555:
>>> 
'itk::Statistics::Histogram<TMeasurement,VMeasurementVectorSize,TFrequencyCo
>>> ntainer>::GetFrequency': overriding virtual function return type 
differs and
>>> is not covariant from
>>> 'itk::Statistics::Sample<TMeasurementVector>::GetFrequency'
>>>         with
>>>         [
>>>             TMeasurement=double,
>>>             VMeasurementVectorSize=6,
>>>
>>> TFrequencyContainer=itk::Statistics::DenseFrequencyContainer<double>
>>>         ]
>>>         and
>>>         [
>>>             TMeasurementVector=itk::FixedArray<double,6>
>>>         ]
>>>         itkSample.h(112) : see declaration of
>>> 'itk::Statistics::Sample<TMeasurementVector>::GetFrequency'
>>>         with
>>>         [
>>>             TMeasurementVector=itk::FixedArray<double,6>
>>>         ]
>>> itkHistogram.h(282) : error C2555:
>>> 
'itk::Statistics::Histogram<TMeasurement,VMeasurementVectorSize,TFrequencyCo
>>> ntainer>::GetTotalFrequency': overriding virtual function return type
>>> differs and is not covariant from
>>> 'itk::Statistics::Sample<TMeasurementVector>::GetTotalFrequency'
>>>         with
>>>         [
>>>             TMeasurement=double,
>>>             VMeasurementVectorSize=6,
>>>
>>> TFrequencyContainer=itk::Statistics::DenseFrequencyContainer<double>
>>>         ]
>>>         and
>>>         [
>>>             TMeasurementVector=itk::FixedArray<double,6>
>>>         ]
>>>         itkSample.h(115) : see declaration of
>>> 'itk::Statistics::Sample<TMeasurementVector>::GetTotalFrequency'
>>>         with
>>>         [
>>>             TMeasurementVector=itk::FixedArray<double,6>
>>>         ]
>>>
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>>
>> -- 
>> ===========================================================
>> Dr. Stephen R. Aylward
>> Associate Professor of Radiology
>> Adjunct Associate Professor of Computer Science and Surgery
>> http://caddlab.rad.unc.edu
>> aylward at unc.edu
>> (919) 966-9695
>>
>>
>>
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