oo_hdf

Object oriented fortran HDF5 module

This library aims to create a group of classes in fortran to interact with HDF5.

Contents:

This library as two main files, one with high level hdf5 routines (H5_func_mod.f90), the other with classes wrapping those routines (H5_OO_mod.f90).

The function module was inspired, extends and has several of the functions present in HDF5_utils.

The classes module has the same base structure of mo_netcdf.

There are two main classes, H5Group and H5Dataset. The H5File is extended from the H5Group. All classes can read and write attributes from the H5Attributable class.

Tested

This library was tested with versions:

• HDF5: 1.8.11, 1.8.16
• gfortran: 4.8.*, 5.4.*

The following methods have been tested in several ways, most of them in production code:

• All H5File
• All H5Group
• All H5Attributable
• All H5Dataset, but:
  • getDataset only integer 8, 16, 32 and real 32 up to 3 dimensions (:,:,:)
  • setDataset with more than 4 dimensions is not tested
  • getBlock with more than 2 dimensions is not tested
  • extendDataset was only tested with int16 array of 3 and 4 dimensions

TODO

• One example of the definition of a netCDF file with this library.
• A way to write blocks of arrays.
• A way to define more than one dimension to be extensible.
• Implement more functions of the HDF5 library.

Interface

H5File

type(H5File) :: file

file = H5File(' path of the file ', status, mode)
!status can be: (OLD, O, NEW, N, REPLACE, RP), not case sensitive
!mode can be: (READ, R, WRITE, W, READWRITE, RW), not case sensitive

call file%closeFile()

H5Group

type(H5Group) :: newgroup
type(H5Group) :: oldgroup

This class must always be called from an object of the same class (H5Group or H5File)

call file%setGroup('name of the new group', newgroup)
call newgroup%openGroup('name of an existing group', oldgroup)
call oldgroup%closeGroup()

call newgroup%getNumObj(number_of_objects)
! number_of_objects is integer 32 bits, method counts the all the groups and datasets in a group

call newgroup%getObjNameByIdx(idx, obj_name)
! method to retrieve the names of the objects in a group

call newgroup%isDset(obj_name)
! logical method that verifies if an object is a Dataset

call newgroup%isGrp(obj_name)
! logical method that verifies if an object is a Group

H5Dataset

type(H5Dataset) :: newdataset
newdataset = H5Dataset('Name of the dataset', parent group)

Define the chunk size of the dataset:

call newdataset%setChunkSize(chunksize)
! chunksize is an integer, if not defined is by default 100

Define the compression level of the dataset:

call newdataset%setCompressionLevel(CompressionLevel)
! CompressionLevel is an integer that must vary between 0 and 9, if not defined is by default 9

Define the fill value of the dataset:

call newdataset%setFillValue(fillvalue)
! fillvalue is an integer, if not defined is by default 0

Define the dataset is extendable in n dimentions:

call newdataset%setExtendable(n)
! n is an integer less or equal to the dataset dimensions
! the dataset gets extended from the last rank to the start
! if newdataset has 4 dimensions (:,:,:,:) and we call newdataset%setExtendable(2),
! the last two dimensions become extendable

Define an empty dataset:

call newdataset%setEmpty()

Get the dataset rank:

call newdataset%getRank(rank)
!rank is an integer

Get the dataset dimensions:

call newdataset%getDims(dims)
!Dims must be an integer array with the dataset rank

Define dimension (scale) of an array

type(H5Dataset) :: dim_dset
call dim_dset%setDataset(x)
call dim_dset%defScale(dimension_name)
!dimension_name the name you wish to attribute to the scale, it is optional

Link a dimension (scale) to an array

call newdataset%setScale(dim_dset,idx_dim)
!dim_dset is the scale object you wish to link with your dataset
!idx_dim is an integer with the rank of the dataset where you will link the scale

Read the entire dataset:

call newdataset%getDataset(dset_array)
!dset_array can be an array of 1 to 6 dimensions
!dset_array can be an integer of 32 bits or a real of 64 bits
!the dataset inside the file can be of any kind lower or equal of those.

Read a block of a dataset:

call newdataset%getBlock(offset, shape, d_array)
!offset is a one dimension integer of 64 bits array with the size of the rank of the dataset to read,
!this array must have the starting points of where you will read the array
!
!shape is a one dimension integer of 64 bits array with the size of the rank of the dataset to read,
!this array must have the size of the portion the array you want to read
!
!dset_array can be an array of 1 to 5 dimensions
!dset_array can be an integer or a real of 32 bits

Write a Dataset:

call newdataset%setDataset(dset_array)
!dset_array can be an array of 1 to 6 dimensions
!dset_array can be an integer of 8, 16 or 32 bits
!dset_array can be a real of 32 or 64 bits

Extend a Dataset:

call newdataset%extendDataset(new_size, offset, dshape, val)
!dset_array can be an array of 1 to 6 dimensions
!dset_array can be an integer of 8, 16 or 32 bits
!dset_array can be a real of 32 or 64 bits
!
!new_size is a one dimension integer of 64 bits array with the size of the rank of the dataset to write,
!this array must have the new total shape of the array you want to extend
!
!offset is a one dimension integer of 64 bits array with the size of the rank of the dataset to write,
!this array must have the starting points of where you will start writing the array
!
!dshape is a one dimension integer of 64 bits array with the size of the rank of the dataset to extend,
!this array must have the size of the portion the array you want to write
!

H5Attributable

This class is only accessed from an object of class H5Group or H5Dataset.

Verify if an attribute exists:

if ( newdataset%Attr_exists(a_name) ) then
      print*,a_name//' exists'
end if
!Attr_exists is a logical function
!a_name is the name of the attribute to check

Get the number of attributes of an object:

call newdataset%getNumberAttrs(number_of_attributes)
!number_of_attributes is an integer of 32 bits

get the name of an attribute by index, the attributes names are retrived by alphabetical order

call newdataset%getAttNameByIdx(idx, a_name)
!idx is an integer of 32 bits
!a_name is the name of the attribute to check

Read an attribute:

call newdataset%getAttribute(a_name, val)
call file%getAttribute(a_name, val)
call newgroup%getAttribute(a_name, val)
!a_name is the name of the attribute to read
!val can be of type character, integer or real(32 or 64 bits)
!val can be a scalar or an array of one dimension.

Write an attribute:

call newdataset%setAttribute(a_name, val)
call file%setAttribute(a_name, val)
call newgroup%setAttribute(a_name, val)
!a_name is the name of the attribute to read
!val can be of type character, integer or real(32 or 64 bits)
!val can be a scalar or an array of one dimension.

Examples:

• Write file, dataset and attribute:

 type(H5File) :: f1
 type(H5Dataset) :: d1, d2
 type(H5Group) :: g1

 !Open a new, write only, file
 f1=H5File("new_test_file.h5", "N", "W")
 !write an attribute in /
 call f1%setAttribute('root_atribute',42)
 !initialize a dataset in /
 d1=H5Dataset('2d_i32',f1)
 !set the fillvalue of d1 dataset to -1
 call d1%setFillValue(-1)
 !define a new group in /
 call f1%setGroup('newgroup',g1)
 !initialize a dataset in group "newgroup"
 d2=H5Dataset('4d_r64',g1)

 do i=1,size(test_arr(:,1))
   do j=1,size(test_arr(1,:))
     test_arr(i,j)=i*j
   end do
 end do
 !write the contents of test_arr to d1 dataset in 8 bits precision
 call d1%setDataset(int(test_arr,1))
 !write an attribute in d1 dataset
 call d1%setAttribute('dataset_atribute',int(42,2))
 !write one array in double precision to d2 dataset
 call d2%setDataset(real([[1],[2],[4],[5]],DP))
 !write an attribute in group g1
 call g2%setAttribute('att1', int([4,4,2,5,4,6,3,1,1,5,5,2,4,2154545,6,2,4,7,6],4))
 !close hdf5 file
 call f1%closeFile()

• Read the contents of a HDF5 file:

!Open an existing, read only, file
f1=H5File("new_test_file.h5", "O", "R")
!read and attribute in /
call f1%getAttribute('thgttg',i)
!open on group in /
call f1%openGroup('newgroup',g1)
!initialize a dataset in /
d1=H5Dataset('2d_i32',f1)
!read an attribute in d1 dataset
call d1%getAttribute('att1',read_a)
!initialize a dataset in group "newgroup"
d2=H5Dataset('4d_r64',g1)
!read the contents of d2 dataset
call d2%getDataset(r8_dset)
!close hdf5 file
call f1%closeFile()