[Insight-users] itkHistogram with double, comments

[Miller, James V (Research)]

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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