Create HDF5 attribute

R function to create an HDF5 attribute and defining its dimensionality.

Usage

h5createAttribute(
  obj,
  attr,
  dims,
  maxdims = dims,
  file,
  storage.mode = "double",
  H5type = NULL,
  size = NULL,
  encoding = NULL,
  native = FALSE
)

Arguments

obj

The name (character) of the object the attribute will be attached to. For advanced programmers it is possible to provide an object of class H5IdComponent representing a H5 object identifier (file, group, dataset). See H5Fcreate(), H5Fopen(), H5Gcreate(), H5Gopen(), H5Dcreate(), H5Dopen() to create an object of this kind.

attr

Name of the attribute to be created.

dims

The dimensions of the attribute as a numeric vector. If NULL, a scalar dataspace will be created instead.

maxdims

The maximum extension of the attribute.

file

The filename (character) of the file in which the dataset will be located. For advanced programmers it is possible to provide an object of class H5IdComponent representing an H5 location identifier. See H5Fcreate(), H5Fopen(), H5Gcreate(), H5Gopen() to create an object of this kind. The file argument is not required, if the argument obj is of type H5IdComponent.

storage.mode

The storage mode of the data to be written. Can be obtained by storage.mode(mydata).

H5type

Advanced programmers can specify the datatype of the dataset within the file, either as a string with one of the available datatypes listed in h5const("H5T"), or as the output of H5Tcopy(). If H5type is specified the argument storage.mode is ignored. It is recommended to use storage.mode.

size

The maximum string length when storage.mode='character'. If this is specified, HDF5 stores each string of attr as fixed length character arrays. Together with compression, this should be efficient.

If this argument is set to NULL, HDF5 will instead store variable-length strings.

encoding

The encoding of the string data type. Valid options are "ASCII" or "UTF-8".

native

An object of class logical. If TRUE, array-like objects are treated as stored in HDF5 row-major rather than R column-major orientation. Using native = TRUE increases HDF5 file portability between programming languages. A file written with native = TRUE should also be read with native = TRUE

Value

Returns TRUE is attribute was created successfully and FALSE otherwise.

Details

Creates a new attribute and attaches it to an existing HDF5 object. The function will fail, if the file doesn't exist or if there exists already another attribute with the same name for this object.

You can use h5writeAttribute() immediately. It will create the attribute for you.

References

https://portal.hdfgroup.org/display/HDF5

Author

Bernd Fischer

Examples


h5File <- tempfile(pattern = "ex_createAttribute.h5")
h5createFile(h5File)
h5write(1:1, h5File, "A")
fid <- H5Fopen(h5File)
did <- H5Dopen(fid, "A")
h5createAttribute(did, "time", c(1, 10))
#> [1] TRUE
H5Dclose(did)
H5Fclose(fid)