mpi4py.MPI.Datatype

class mpi4py.MPI.Datatype

Bases: object

Datatype object.

static __new__(cls, datatype=None)

Parameters:

datatype (Datatype | None)

Return type:

Self

Methods Summary

Commit()	Commit the datatype.
Create_contiguous(count)	Create a contiguous datatype.
Create_darray(size, rank, gsizes, distribs, ...)	Create a datatype for a distributed array on Cartesian process grids.
Create_f90_complex(p, r)	Return a bounded complex datatype.
Create_f90_integer(r)	Return a bounded integer datatype.
Create_f90_real(p, r)	Return a bounded real datatype.
Create_hindexed(blocklengths, displacements)	Create an indexed datatype.
Create_hindexed_block(blocklength, displacements)	Create an indexed datatype with constant-sized blocks.
Create_hvector(count, blocklength, stride)	Create a vector (strided) datatype with stride in bytes.
Create_indexed(blocklengths, displacements)	Create an indexed datatype.
Create_indexed_block(blocklength, displacements)	Create an indexed datatype with constant-sized blocks.
Create_keyval([copy_fn, delete_fn, nopython])	Create a new attribute key for datatypes.
Create_resized(lb, extent)	Create a datatype with a new lower bound and extent.
Create_struct(blocklengths, displacements, ...)	Create a general composite (struct) datatype.
Create_subarray(sizes, subsizes, starts[, order])	Create a datatype for a subarray of a multidimensional array.
Create_vector(count, blocklength, stride)	Create a vector (strided) datatype.
Delete_attr(keyval)	Delete attribute value associated with a key.
Dup()	Duplicate a datatype.
Free()	Free the datatype.
Free_keyval(keyval)	Free an attribute key for datatypes.
Get_attr(keyval)	Retrieve attribute value by key.
Get_contents()	Return the input arguments used to create a datatype.
Get_envelope()	Return the number of input arguments used to create a datatype.
Get_extent()	Return lower bound and extent of datatype.
Get_name()	Get the print name for this datatype.
Get_size()	Return the number of bytes occupied by entries in the datatype.
Get_true_extent()	Return the true lower bound and extent of a datatype.
Get_value_index(value, index)	Return a predefined pair datatype.
Match_size(typeclass, size)	Find a datatype matching a specified size in bytes.
Pack(inbuf, outbuf, position, comm)	Pack into contiguous memory according to datatype.
Pack_external(datarep, inbuf, outbuf, position)	Pack into contiguous memory according to datatype.
Pack_external_size(datarep, count)	Determine the amount of space needed to pack a message.
Pack_size(count, comm)	Determine the amount of space needed to pack a message.
Set_attr(keyval, attrval)	Store attribute value associated with a key.
Set_name(name)	Set the print name for this datatype.
Unpack(inbuf, position, outbuf, comm)	Unpack from contiguous memory according to datatype.
Unpack_external(datarep, inbuf, position, outbuf)	Unpack from contiguous memory according to datatype.
decode()	Convenience method for decoding a datatype.
f2py(arg)
free()	Call Free if not null or predefined.
fromcode(code)	Get predefined MPI datatype from character code or type string.
fromhandle(handle)	Create object from MPI handle.
py2f()
tocode()	Get character code or type string from predefined MPI datatype.

Attributes Summary

combiner	Combiner.
contents	Contents.
envelope	Envelope.
extent	Extent.
handle	MPI handle.
is_named	Is a named datatype.
is_predefined	Is a predefined datatype.
lb	Lower bound.
name	Print name.
size	Size (in bytes).
true_extent	True extent.
true_lb	True lower bound.
true_ub	True upper bound.
typechar	Character code.
typestr	Type string.
ub	Upper bound.

Methods Documentation

Commit()

Commit the datatype.

Return type:

Self

Create_contiguous(count)

Create a contiguous datatype.

Parameters:

count (int)

Return type:

Self

Create_darray(size, rank, gsizes, distribs, dargs, psizes, order=ORDER_C)

Create a datatype for a distributed array on Cartesian process grids.

Parameters:

• size (int)

• rank (int)

• gsizes (Sequence[int])

• distribs (Sequence[int])

• dargs (Sequence[int])

• psizes (Sequence[int])

• order (int)

Return type:

Self

classmethod Create_f90_complex(p, r)

Return a bounded complex datatype.

Parameters:

• p (int)

• r (int)

Return type:

Self

classmethod Create_f90_integer(r)

Return a bounded integer datatype.

Parameters:

r (int)

Return type:

Self

classmethod Create_f90_real(p, r)

Return a bounded real datatype.

Parameters:

• p (int)

• r (int)

Return type:

Self

Create_hindexed(blocklengths, displacements)

Create an indexed datatype.

Note

Displacements are measured in bytes.

Parameters:

• blocklengths (Sequence[int])

• displacements (Sequence[int])

Return type:

Self

Create_hindexed_block(blocklength, displacements)

Create an indexed datatype with constant-sized blocks.

Note

Displacements are measured in bytes.

Parameters:

• blocklength (int)

• displacements (Sequence[int])

Return type:

Self

Create_hvector(count, blocklength, stride)

Create a vector (strided) datatype with stride in bytes.

Parameters:

• count (int)

• blocklength (int)

• stride (int)

Return type:

Self

Create_indexed(blocklengths, displacements)

Create an indexed datatype.

Parameters:

• blocklengths (Sequence[int])

• displacements (Sequence[int])

Return type:

Self

Create_indexed_block(blocklength, displacements)

Create an indexed datatype with constant-sized blocks.

Parameters:

• blocklength (int)

• displacements (Sequence[int])

Return type:

Self

classmethod Create_keyval(copy_fn=None, delete_fn=None, nopython=False)

Create a new attribute key for datatypes.

Parameters:

• copy_fn (Callable[[Datatype, int, Any], Any] | None)

• delete_fn (Callable[[Datatype, int, Any], None] | None)

• nopython (bool)

Return type:

int

Create_resized(lb, extent)

Create a datatype with a new lower bound and extent.

Parameters:

• lb (int)

• extent (int)

Return type:

Self

classmethod Create_struct(blocklengths, displacements, datatypes)

Create a general composite (struct) datatype.

Note

Displacements are measured in bytes.

Parameters:

• blocklengths (Sequence[int])

• displacements (Sequence[int])

• datatypes (Sequence[Datatype])

Return type:

Self

Create_subarray(sizes, subsizes, starts, order=ORDER_C)

Create a datatype for a subarray of a multidimensional array.

Parameters:

• sizes (Sequence[int])

• subsizes (Sequence[int])

• starts (Sequence[int])

• order (int)

Return type:

Self

Create_vector(count, blocklength, stride)

Create a vector (strided) datatype.

Parameters:

• count (int)

• blocklength (int)

• stride (int)

Return type:

Self

Delete_attr(keyval)

Delete attribute value associated with a key.

Parameters:

keyval (int)

Return type:

None

Dup()

Duplicate a datatype.

Return type:

Self

Free()

Free the datatype.

Return type:

None

classmethod Free_keyval(keyval)

Free an attribute key for datatypes.

Parameters:

keyval (int)

Return type:

int

Get_attr(keyval)

Retrieve attribute value by key.

Parameters:

keyval (int)

Return type:

int | Any | None

Get_contents()

Return the input arguments used to create a datatype.

Return type:

tuple[list[int], list[int], list[int], list[Datatype]]

Get_envelope()

Return the number of input arguments used to create a datatype.

Return type:

tuple[int, int, int, int, int]

Get_extent()

Return lower bound and extent of datatype.

Return type:

tuple[int, int]

Get_name()

Get the print name for this datatype.

Return type:

str

Get_size()

Return the number of bytes occupied by entries in the datatype.

Return type:

int

Get_true_extent()

Return the true lower bound and extent of a datatype.

Return type:

tuple[int, int]

classmethod Get_value_index(value, index)

Return a predefined pair datatype.

Parameters:

• value (Datatype)

• index (Datatype)

Return type:

Self

classmethod Match_size(typeclass, size)

Find a datatype matching a specified size in bytes.

Parameters:

• typeclass (int)

• size (int)

Return type:

Self

Pack(inbuf, outbuf, position, comm)

Pack into contiguous memory according to datatype.

Parameters:

• inbuf (BufSpec)

• outbuf (BufSpec)

• position (int)

• comm (Comm)

Return type:

int

Pack_external(datarep, inbuf, outbuf, position)

Pack into contiguous memory according to datatype.

Uses the portable data representation external32.

Parameters:

• datarep (str)

• inbuf (BufSpec)

• outbuf (BufSpec)

• position (int)

Return type:

int

Pack_external_size(datarep, count)

Determine the amount of space needed to pack a message.

Uses the portable data representation external32.

Note

Returns an upper bound measured in bytes.

Parameters:

• datarep (str)

• count (int)

Return type:

int

Pack_size(count, comm)

Determine the amount of space needed to pack a message.

Note

Returns an upper bound measured in bytes.

Parameters:

• count (int)

• comm (Comm)

Return type:

int

Set_attr(keyval, attrval)

Store attribute value associated with a key.

Parameters:

• keyval (int)

• attrval (Any)

Return type:

None

Set_name(name)

Set the print name for this datatype.

Parameters:

name (str)

Return type:

None

Unpack(inbuf, position, outbuf, comm)

Unpack from contiguous memory according to datatype.

Parameters:

• inbuf (BufSpec)

• position (int)

• outbuf (BufSpec)

• comm (Comm)

Return type:

int

Unpack_external(datarep, inbuf, position, outbuf)

Unpack from contiguous memory according to datatype.

Uses the portable data representation external32.

Parameters:

• datarep (str)

• inbuf (BufSpec)

• position (int)

• outbuf (BufSpec)

Return type:

int

decode()

Convenience method for decoding a datatype.

Return type:

tuple[Datatype, str, dict[str, Any]]

classmethod f2py(arg)

Parameters:

arg (int)

Return type:

Datatype

free()

Call Free if not null or predefined.

Return type:

None

classmethod fromcode(code)

Get predefined MPI datatype from character code or type string.

Parameters:

code (str)

Return type:

Datatype

classmethod fromhandle(handle)

Create object from MPI handle.

Parameters:

handle (int)

Return type:

Datatype

py2f()

Return type:

int

tocode()

Get character code or type string from predefined MPI datatype.

Return type:

str

Attributes Documentation

combiner

Combiner.

contents

Contents.

envelope

Envelope.

extent

Extent.

handle

MPI handle.

is_named

Is a named datatype.

is_predefined

Is a predefined datatype.

lb

Lower bound.

name

Print name.

size

Size (in bytes).

true_extent

True extent.

true_lb

True lower bound.

true_ub

True upper bound.

typechar

Character code.

typestr

Type string.

ub

Upper bound.