[vtkusers] Attaching additional metadata information to vtkDoubleArray

[Alexander Pletzer]

Hi David,

Thanks, that worked! I'm appending the example code below for future 
reference.

Do we know what char *location mean below? This argument is required 
when creating the key.

Best,

--Alex

// vtk includes
#include <vtkDoubleArray.h>
#include <vtkInformation.h>
#include <vtkInformationDoubleVectorKey.h>

// std includes
#include <iostream>

int main() {

// create a 2-element array
vtkDoubleArray* array = vtkDoubleArray::New();
array->SetName("array");
array->SetNumberOfComponents(1);
array->SetNumberOfTuples(2);
array->SetValue(0, 1.);
array->SetValue(1, 2.);

// access the info (presently none stored)
vtkInformation* info = array->GetInformation();

// add one attribute, a double vector
const char *name = "mykey";
const char *location = ""; // not sure what this is?
xint length = 3;
vtkInformationDoubleVectorKey *key = new 
vtkInformationDoubleVectorKey(name,
location,
length);
double values[] = {0.1, 0.2, 0.3};
info->Set(key, values[0], values[1],values[2]);

info->Print(std::cout);
array->Delete();
// array->Delete will also delete key (do not call delete key)
}



On 02/06/2012 04:56 PM, David E DeMarle wrote:
> Add #include "vtkInformationDoubleVectorKey.h" and #2 should work.
>
> David E DeMarle
> Kitware, Inc.
> R&D Engineer
> 21 Corporate Drive
> Clifton Park, NY 12065-8662
> Phone: 518-881-4909
>
>
>
> On Mon, Feb 6, 2012 at 1:21 PM, Alexander Pletzer<pletzer at txcorp.com>  wrote:
>> Hi VTK'ians,
>>
>> I'm trying to figure out how additional (metadata) information can be
>> attached to vtk objects such as vtkDoubleArray. Specifically I would like to
>> attach a vector of 3 doubles.
>> It looks like vtkInformation acts as a hash map and is designed for that
>> purpose. Although it is straightforward to access the vtkInformation pointer
>> to the array using the GetInformation method, I've been unable to set
>> key/value pairs to the vtkInformation object, mainly because I cannot figure
>> out how to build the key, see code below.
>>
>> Thanks in advance for any help!
>>
>> Cheers,
>>
>> --Alex
>>
>> // vtk includes
>> #include<vtkDoubleArray.h>
>> #include<vtkInformation.h>
>>
>> // std includes
>> #include<iostream>
>>
>>
>> int main() {
>> // creation of a simple array
>> vtkDoubleArray* array = vtkDoubleArray::New();
>> array->SetName("array");
>> array->SetNumberOfComponents(1);
>> array->SetNumberOfTuples(2);
>> array->SetValue(0, 1.);
>> array->SetValue(1, 2.);
>>
>> access the pointer to the info
>> vtkInformation* info = array->GetInformation();
>>
>> // don't know how to create the key and values
>>
>> // THIS WON'T COMPILE
>> vtkInformationDoubleVectorKey *key = vtkInformationDoubleVectorKey::New();
>> /// error: no New
>>
>> // THIS WON'T COMPILE
>> const char *name = "mykey";
>> const char *location = "";
>> int length = 3;
>> vtkInformationDoubleVectorKey *key = new vtkInformationDoubleVectorKey(name,
>> location,
>> length); // invalid use of incomplete type ‘struct
>> vtkInformationDoubleVectorKey’
>>
>> // build values
>> double values[] = {1., 2., 3.};
>>
>> // Once I have key and values built, I want to call....
>> info->Set(key, values, 3);
>>
>> info->Print(std::cout);
>> array->Delete();
>> }
>>
>>
>>
>>
>> std::cout<<  "array has info "<<  array->HasInformation()<<  '\n';
>>
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