compression Module Reference

Defines the base class of the type compression_class. This class contains the code and buffers to hold compressed and uncompressed data. 2D matrix data is compressed using a singular value decomposition. See del-Castillo-Negrete et. al. doi:10.1016/j.jcp.2006.07.022. More...

Data Types
type	compression_class
	Base class containing buffers for compressed and uncompressed data. More...
interface	compression_construct
	Interface for the construction of compression_class types using compression_construct_new or compression_construct_netcdf. More...
type	compression_pointer
	Pointer to a compression object. Used for creating arrays of compression pointers. This is needed because fortran does not allow arrays of pointers directly. More...

Functions/Subroutines
type(compression_class) function, pointer	compression_construct_new (data_in, svd_cut_off)
	Construct a compression_class object.
type(compression_class) function, pointer	compression_construct_netcdf (ncid, name)
	Construct a compression_class object by reading from an netcdf. file.
subroutine	compression_destruct (this)
	Deconstruct a compression_class object.
integer function	compression_get_dimension1 (this)
	Get the ith dimension length.
integer function	compression_get_dimension2 (this)
	Get the jth dimension length.
subroutine	compression_decompress (this)
	Decompress the data.
subroutine	compression_cleanup (this)
	Cleanup decompressed data.
subroutine	compression_define (this, ncid, name)
	Define variables for the compressed data.
subroutine	compression_write (this, ncid, name)
	Cleanup decompressed data.

Variables
real(rprec), parameter	compression_max_percentage = 100.0
	Maximum compressed size before uncompressed buffers are stored.
character(len= *), parameter	compression_data_buffer_post = 'data_buffer'
	Postfix for the data buffer.
character(len= *), parameter	compression_u_buffer_post = 'u_buffer'
	Postfix for the data buffer.
character(len= *), parameter	compression_wvt_buffer_post = 'wvt_buffer'
	Postfix for the data buffer.
character(len= *), parameter	compression_data_dim_post = 'data_dim'
	Postfix for the data buffer.

Detailed Description

Defines the base class of the type compression_class. This class contains the code and buffers to hold compressed and uncompressed data. 2D matrix data is compressed using a singular value decomposition. See del-Castillo-Negrete et. al. doi:10.1016/j.jcp.2006.07.022.

Function/Subroutine Documentation

compression_cleanup()

subroutine compression::compression_cleanup

(

type (compression_class), pointer

this

)

Cleanup decompressed data.

If the data dimensions arrays or the U and WVT is allocated, then delete the data buffer. Otherwise the data is stored uncompressed.

Parameters

[in,out]

this

A compression_class instance.

compression_construct_netcdf()

type (compression_class) function, pointer compression::compression_construct_netcdf	(	integer, intent(in)	ncid,
		character (len=*), intent(in)	name
	)

Construct a compression_class object by reading from an netcdf. file.

Constructs data from a precompressed netcdf file.

Parameters

[in]	ncid	A netcdf file id.
[in]	name	A netcdf variable name id.
[in]	name	Flag discribing how the data was compressed.

Returns

A pointer to a constructed compression_class object.

compression_construct_new()

type (compression_class) function, pointer compression::compression_construct_new	(	real (rprec), dimension(:,:), intent(in)	data_in,
		real (rprec), intent(in)	svd_cut_off
	)

Construct a compression_class object.

Constructs compression object and compresses the data buffer if compression meets the specified criteria.

Parameters

[in]	data_in	Data buffer to compress. This gets copied to the internal storage buffer.
[in]	svn_cut_off	Cutoff value for determining the number of singular values to use for compression.

Returns

A pointer to a constructed compression_class object.

compression_decompress()

subroutine compression::compression_decompress

(

type (compression_class), pointer

this

)

Decompress the data.

Checks if the U and WVT arrays are allocated. If they are not the data_buffer was left uncompressed. If the data dimensions is also unallocated, then the orginal data buffer was all zeros otherwise data is uncompressed by matrix a multiplication.

Parameters

[in,out]

this

A compression_class instance.

compression_define()

subroutine compression::compression_define	(	type (compression_class), intent(in)	this,
		integer, intent(in)	ncid,
		character (len=*), intent(in)	name
	)

Define variables for the compressed data.

Defines the netcdf variables for writting compressed data to a netcdf file.

Parameters

[in]	this	A compression_class instance.
[in]	ncid	Netcdf file id.
[in]	name	Base name of variables to compress.

Returns

The flag indicating which buffer was stored.

compression_destruct()

subroutine compression::compression_destruct

(

type (compression_class), pointer

this

)

Deconstruct a compression_class object.

Deallocates memory and uninitializes a compression_class object.

Parameters

[in,out]

this

A compression_class instance.

compression_get_dimension1()

integer function compression::compression_get_dimension1

(

type (compression_class), pointer

this

)

Get the ith dimension length.

Retrives the uncompressed dimension of the first data buffer index. This can be used without needing to decompress the data first.

Parameters

[in,out]

this

A compression_class instance.

Returns

The size of the ith dimension of the uncompressed data buffer.

compression_get_dimension2()

integer function compression::compression_get_dimension2

(

type (compression_class), pointer

this

)

Get the jth dimension length.

Retrives the uncompressed dimension of the second data buffer index. This can be used without needing to decompress the data first.

Parameters

[in,out]

this

A compression_class instance.

Returns

The size of the jth dimension of the uncompressed data buffer.

compression_write()

subroutine compression::compression_write	(	type (compression_class), intent(in)	this,
		integer, intent(in)	ncid,
		character (len=*), intent(in)	name
	)

Cleanup decompressed data.

If the data dimensions arrays or the U and WVT is allocated, then delete the data buffer. Otherwise the data is stored uncompressed.

Parameters

[in,out]	this	A compression_class instance.
[in]	ncid	A netcdf file handle.
[in]	name	The name to write the variable to.