petsc4py.PETSc.IS#

class petsc4py.PETSc.IS#

Bases: Object

A collection of indices.

IS objects are used to index into vectors and matrices and to set up vector scatters.

See also

IS

Enumerations

Type

The index set types.

Methods Summary

`allGather`()	Concatenate index sets stored across processors.
`buildTwoSided`([toindx])	Create an index set describing a global mapping.
`complement`(nmin, nmax)	Create a complement index set.
`copy`([result])	Copy the contents of the index set into another.
`create`([comm])	Create an IS.
`createBlock`(bsize, indices[, comm])	Create a blocked index set.
`createGeneral`(indices[, comm])	Create an IS with indices.
`createStride`(size[, first, step, comm])	Create an index set consisting of evenly spaced values.
`destroy`()	Destroy the index set.
`difference`(iset)	Return the difference between two index sets.
`duplicate`()	Create a copy of the index set.
`embed`(iset, drop)	Embed `self` into `iset`.
`equal`(iset)	Return whether the index sets have the same set of indices or not.
`expand`(iset)	Return the union of two (possibly unsorted) index sets.
`getBlockIndices`()	Return the indices of an index set with type `IS.Type.BLOCK`.
`getBlockSize`()	Return the number of elements in a block.
`getIndices`()	Return the indices of the index set.
`getInfo`()	Return stride information for an index set with type `IS.Type.STRIDE`.
`getLocalSize`()	Return the process-local length of the index set.
`getSize`()	Return the global length of an index set.
`getSizes`()	Return the local and global sizes of the index set.
`getStride`()	Return size and stride information.
`getType`()	Return the index set type associated with the IS.
`invertPermutation`([nlocal])	Invert the index set.
`isIdentity`()	Return whether the index set has been declared as an identity.
`isPermutation`()	Return whether an index set has been declared to be a permutation.
`isSorted`()	Return whether the indices have been sorted.
`load`(viewer)	Load a stored index set.
`renumber`([mult])	Renumber the non-negative entries of an index set, starting from 0.
`setBlockIndices`(bsize, indices)	Set the indices for an index set with type `IS.Type.BLOCK`.
`setBlockSize`(bs)	Set the block size of the index set.
`setIdentity`()	Mark the index set as being an identity.
`setIndices`(indices)	Set the indices of an index set.
`setPermutation`()	Mark the index set as being a permutation.
`setStride`(size[, first, step])	Set the stride information for an index set with type `IS.Type.STRIDE`.
`setType`(is_type)	Set the type of the index set.
`sort`()	Sort the indices of an index set.
`sum`(iset)	Return the union of two (sorted) index sets.
`toGeneral`()	Convert the index set type to `IS.Type.GENERAL`.
`union`(iset)	Return the union of two (possibly unsorted) index sets.
`view`([viewer])	Display the index set.

Attributes Summary

`array`	View of the index set as an array of integers.
`block_size`	The number of elements in a block.
`identity`	`True` if index set is an identity, `False` otherwise.
`indices`	The indices of the index set.
`local_size`	The local size of the index set.
`permutation`	`True` if index set is a permutation, `False` otherwise.
`size`	The global size of the index set.
`sizes`	The local and global sizes of the index set.
`sorted`	`True` if index set is sorted, `False` otherwise.

Methods Documentation

allGather()#

Concatenate index sets stored across processors.

Collective.

The returned index set will be the same on every processor.

See also

ISAllGather

Source code at petsc4py/PETSc/IS.pyx:304

Return type:: IS

buildTwoSided(toindx=None)#

Create an index set describing a global mapping.

Collective.

This function generates an index set that contains new numbers from remote or local on the index set.

Parameters:: toindx (IS | None) – Index set describing which indices to send, default is to send natural numbering.
Returns:: New index set containing the new numbers from remote or local.
Return type:: IS

See also

ISBuildTwoSided

Source code at petsc4py/PETSc/IS.pyx:333

complement(nmin, nmax)#

Create a complement index set.

Collective.

The complement set of indices is all indices that are not in the provided set (and within the provided bounds).

Parameters:

nmin (int) – Minimum index that can be found in the local part of the complement index set.
nmax (int) – One greater than the maximum index that can be found in the local part of the complement index set.

Return type:

Notes

For a parallel index set, this will generate the local part of the complement on each process.

To generate the entire complement (on each process) of a parallel index set, first call IS.allGather and then call this method.

See also

IS.allGather, ISComplement

Source code at petsc4py/PETSc/IS.pyx:674

copy(result=None)#

Copy the contents of the index set into another.

Collective.

Parameters:: result (IS | None) – The target index set. If None then IS.duplicate is called first.
Returns:: The copied index set. If result is not None then this is returned here.
Return type:: IS

See also

IS.duplicate, ISCopy

Source code at petsc4py/PETSc/IS.pyx:253

create(comm=None)#

Create an IS.

Collective.

Parameters:: comm (Comm | None) – MPI communicator, defaults to Sys.getDefaultComm.
Return type:: Self

See also

ISCreate

Source code at petsc4py/PETSc/IS.pyx:88

createBlock(bsize, indices, comm=None)#

Create a blocked index set.

Collective.

Parameters:

bsize (int) – Block size.
indices (Sequence[int]) – Integer array of indices.
comm (Comm | None) – MPI communicator, defaults to Sys.getDefaultComm.

Return type:

Self

See also

ISCreateBlock

Source code at petsc4py/PETSc/IS.pyx:171

createGeneral(indices, comm=None)#

Create an IS with indices.

Collective.

Parameters:

indices (Sequence[int]) – Integer array.
comm (Comm | None) – MPI communicator, defaults to Sys.getDefaultComm.

Return type:

Self

See also

ISCreateGeneral

Source code at petsc4py/PETSc/IS.pyx:142

createStride(size, first=0, step=0, comm=None)#

Create an index set consisting of evenly spaced values.

Collective.

Parameters:

size (int) – The length of the locally owned portion of the index set.
first (int) – The first element of the index set.
step (int) – The difference between adjacent indices.
comm (Comm | None) – MPI communicator, defaults to Sys.getDefaultComm.

Return type:

Self

See also

ISCreateStride

Source code at petsc4py/PETSc/IS.pyx:204

destroy()#

Destroy the index set.

Collective.

See also

ISDestroy

Source code at petsc4py/PETSc/IS.pyx:75

Return type:: Self

difference(iset)#

Return the difference between two index sets.

Collective.

Parameters:: iset (IS) – Index set to compute the difference with.
Returns:: Index set representing the difference between self and iset.
Return type:: IS

See also

ISDifference

Source code at petsc4py/PETSc/IS.pyx:650

duplicate()#

Create a copy of the index set.

Collective.

See also

IS.copy, ISDuplicate

Source code at petsc4py/PETSc/IS.pyx:239

Return type:: IS

embed(iset, drop)#

Embed self into iset.

Not collective.

The embedding is performed by finding the locations in iset that have the same indices as self.

Parameters:

iset (IS) – The index set to embed into.
drop (bool) – Flag indicating whether to drop indices from self that are not in iset.

Returns:

The embedded index set.

Return type:

IS

See also

ISEmbed

Source code at petsc4py/PETSc/IS.pyx:710

equal(iset)#

Return whether the index sets have the same set of indices or not.

Collective.

Parameters:: iset (IS) – The index set to compare indices with.
Return type:: bool

See also

ISEqual

Source code at petsc4py/PETSc/IS.pyx:550

expand(iset)#

Return the union of two (possibly unsorted) index sets.

Collective.

To compute the union, expand concatenates the two index sets and removes any duplicates.

Parameters:: iset (IS) – Index set to compute the union with.
Returns:: The new, combined, index set.
Return type:: IS

See also

ISExpand

Source code at petsc4py/PETSc/IS.pyx:588

getBlockIndices()#

Return the indices of an index set with type IS.Type.BLOCK.

Not collective.

See also

ISBlockGetIndices

Source code at petsc4py/PETSc/IS.pyx:833

Return type:: ArrayInt

getBlockSize()#

Return the number of elements in a block.

Not collective.

See also

ISGetBlockSize

Source code at petsc4py/PETSc/IS.pyx:437

Return type:: int

getIndices()#

Return the indices of the index set.

Not collective.

See also

ISGetIndices

Source code at petsc4py/PETSc/IS.pyx:789

Return type:: ArrayInt

getInfo()#

Return stride information for an index set with type IS.Type.STRIDE.

Not collective.

Returns:

first (int) – First element of the index set.
step (int) – Difference between adjacent indices.

Return type:

tuple[int, int]

See also

IS.getStride, ISStrideGetInfo

Source code at petsc4py/PETSc/IS.pyx:903

getLocalSize()#

Return the process-local length of the index set.

Not collective.

See also

ISGetLocalSize

Source code at petsc4py/PETSc/IS.pyx:401

Return type:: int

getSize()#

Return the global length of an index set.

Not collective.

See also

ISGetSize

Source code at petsc4py/PETSc/IS.pyx:387

Return type:: int

getSizes()#

Return the local and global sizes of the index set.

Not collective.

Returns:

local_size (int) – The local size.
global_size (int) – The global size.

Return type:

tuple[int, int]

See also

IS.getLocalSize, IS.getSize

Source code at petsc4py/PETSc/IS.pyx:415

getStride()#

Return size and stride information.

Not collective.

Returns:

size (int) – Length of the locally owned portion of the index set.
first (int) – First element of the index set.
step (int) – Difference between adjacent indices.

Return type:

tuple[int, int, int]

See also

ISGetLocalSize, ISStrideGetInfo

Source code at petsc4py/PETSc/IS.pyx:879

getType()#

Return the index set type associated with the IS.

Not collective.

See also

ISGetType

Source code at petsc4py/PETSc/IS.pyx:128

Return type:: str

invertPermutation(nlocal=None)#

Invert the index set.

Collective.

For this to be correct the index set must be a permutation.

Parameters:: nlocal (int | None) – The number of indices on this processor in the resulting index set, defaults to PETSC_DECIDE.
Return type:: IS