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# VecTaggerCreate
create a `VecTagger` context.  This object is used to control the tagging/selection of index sets based on the values in a vector.  This is used, for example, in adaptive simulations when aspects are selected for refinement or coarsening.  The primary intent is that the selected index sets are based purely on the values in the vector, though implementations that do not follow this intent are possible. 
## Synopsis
```
#include "petscvec.h" 
PetscErrorCode VecTaggerCreate(MPI_Comm comm, VecTagger *tagger)
```
Once a `VecTagger` is created (`VecTaggerCreate()`), optionally modified by options (`VecTaggerSetFromOptions()`), and
set up (`VecTaggerSetUp()`), it is applied to vectors with `VecTaggerComputeIS()` to compute the selected index sets.

In many cases, the selection criteria for an index is whether the corresponding value falls within a collection of
boxes: for this common case, `VecTaggerCreateBoxes()` can also be used to determine those boxes.

Provided implementations support tagging based on a box/interval of values (`VECTAGGERABSOLUTE`), based on a box of
values of relative to the range of values present in the vector (`VECTAGGERRELATIVE`), based on where values fall in
the cumulative distribution of values in the vector (`VECTAGGERCDF`), and based on unions (`VECTAGGEROR`) or
intersections (`VECTAGGERAND`) of other criteria.

Collective


## Input Parameter

- ***comm -*** communicator on which the `VecTagger` will operate



## Output Parameter

- ***tagger -*** new Vec tagger context





## See Also
 `VecTagger`, `VecTaggerSetBlockSize()`, `VecTaggerSetFromOptions()`, `VecTaggerSetUp()`, `VecTaggerComputeIS()`, `VecTaggerComputeBoxes()`, `VecTaggerDestroy()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/utils/tagger/interface/tagger.c.html#VecTaggerCreate">src/vec/vec/utils/tagger/interface/tagger.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/tutorials/ex11.c.html">src/ts/tutorials/ex11.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/utils/tagger/tutorials/ex1.c.html">src/vec/vec/utils/tagger/tutorials/ex1.c</A><BR>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/utils/tagger/impls/absolute.c.html#VecTaggerCreate_Absolute">VecTaggerCreate_Absolute in src/vec/vec/utils/tagger/impls/absolute.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/utils/tagger/impls/and.c.html#VecTaggerCreate_And">VecTaggerCreate_And in src/vec/vec/utils/tagger/impls/and.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/utils/tagger/impls/andor.c.html#VecTaggerCreate_AndOr">VecTaggerCreate_AndOr in src/vec/vec/utils/tagger/impls/andor.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/utils/tagger/impls/cdf.c.html#VecTaggerCreate_CDF">VecTaggerCreate_CDF in src/vec/vec/utils/tagger/impls/cdf.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/utils/tagger/impls/or.c.html#VecTaggerCreate_Or">VecTaggerCreate_Or in src/vec/vec/utils/tagger/impls/or.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/utils/tagger/impls/relative.c.html#VecTaggerCreate_Relative">VecTaggerCreate_Relative in src/vec/vec/utils/tagger/impls/relative.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/vec/utils/tagger/impls/simple.c.html#VecTaggerCreate_Simple">VecTaggerCreate_Simple in src/vec/vec/utils/tagger/impls/simple.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/vec/vec/utils/tagger/interface/tagger.c)


[Index of all Vec routines](index.md)  
[Table of Contents for all manual pages](/manualpages/index.md)  
[Index of all manual pages](/manualpages/singleindex.md)