Description Usage Arguments Details Value Author(s)

Selecting and assigning subsets of HDF5-Spaces and HDF5-Datasets

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | ```
subset_h5.H5S(x, d1, ..., op = h5const$H5S_SELECT_SET,
envir = parent.frame())
## S3 method for class 'H5S'
x[d1, ..., op = h5const$H5S_SELECT_SET,
envir = parent.frame()]
subset_h5.H5D(x, d1, ..., dataset_xfer_pl = h5const$H5P_DEFAULT,
flags = getOption("hdf5r.h5tor_default"), drop = TRUE,
envir = parent.frame())
## S3 method for class 'H5D'
x[d1, ..., dataset_xfer_pl = h5const$H5P_DEFAULT,
flags = getOption("hdf5r.h5tor_default"), drop = TRUE,
envir = parent.frame()]
subset_assign_h5.H5D(x, d1, ..., dataset_xfer_pl = h5const$H5P_DEFAULT,
envir = parent.frame(), value)
## S3 replacement method for class 'H5D'
x[d1, ..., dataset_xfer_pl = h5const$H5P_DEFAULT,
envir = parent.frame()] <- value
``` |

`x` |
The |

`d1` |
First dimension of the object |

`...` |
Used for other dimension of the object |

`op` |
Operation to perform on the |

`envir` |
The environment in which the dimension indices |

`dataset_xfer_pl` |
An object of class |

`flags` |
Some flags governing edge cases of conversion from HDF5 to R. This is related to how integers are being treated and
the issue of R not being able to natively represent 64bit integers and not at all being able to represent unsigned 64bit integers
(even using add-on packages). The constants governing this are part of |

`drop` |
Logical. When reading data, should dimensions of size 1 be dropped. |

`value` |
The value to assign to the dataset |

Used for subsetting HDF5-Datasets or HDF5-Spaces or for assigning data into HDF5-Datasets. There are some differences to consider with R itself.

Most importantly HDF5-COMPOUND objects only have a single dimension internally to HDF5 (a vector), but they correspond to R-data.frames,
which are 2 dimensional. For an HDF5 COMPOUND object, it is currently not possible to only sub-select a specific column.
All columns have to be extracted (using 1-dimensional access with `[`

and can then be subset in R itself.
The same is true for writing a COMPOUND object (`H5T_COMPOUND`

). A complete data-frame
is needed, not just a subset of the columns.

Another important differences is for datasets of HDF5-ARRAY type `H5T_ARRAY`

where the access to the object is only for the dimension of the object itself, not including the dimensions of the underlying array type.

For `x`

being a `H5S`

, the same object is returned, but with the selection set as requested. For
`H5D`

it retrieves the subset of data requested or sets the subset of data assigned, as for any n-dimensional array
in R.

Holger Hoefling

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