Show all elements available in the file:

By default, a list of dataset names is returned:

Import the file structure, specifying the format explicitly:

Import contents of a dataset by specifying its name:

Import dimensions and data format for all datasets in the file:

Import dimensions and data format of a single dataset:

Import 8-bit RGB raster data and render it as an Image object:

Export a matrix to HDF5:

Show the datasets contained in this file:

Export a named dataset:

Export two matrices to HDF5:

Export a named dataset with given data type:

Import the data format:

Export a named data type and a group that links to it:

Import the file structure:

Import attributes of all objects in the file:

Import attributes of a specific dataset:

Import attributes of the second dataset in the file:

The order of datasets in the file can be checked by calling:

Import attributes of multiple objects:

Get data from all datasets in the file:

Import data from the "Complex64" dataset inside the "Complex" group:

Import data from the third dataset in the file:

Get data from all datasets in a given group:

Import data from every dataset or group in a list:

Check what filters were applied to each dataset in the file:

Get data type description for every dataset in the file:

Simple numeric and string types have one-word descriptions:

"DataFormat" for a compound type shows class and structure:

"DataFormat" for enumerated types includes class, base data format and a list of values and names:

"DataFormat" for array types includes class, base data format and dimensions:

"DataFormat" for byte arrays includes class and length:

Import names of all datasets in a file:

"Datasets" is the default HDF5 element:

Get dimensions of all datasets in a file:

Import dimensions of all datasets under a given group:

Dimensions of data with only a single element are indicated by an empty list:

Get dimensions of a specific dataset:

Specify the dataset using its index:

Import names of all groups in the file, with each group listed only once:

The structure of a structured HDF5 file:

Structure of a flat HDF5 file:

Get a legend:

Get the file summary:

Attach attributes to the root group:

Specify data format for attributes:

Export dataset's attributes both in "Datasets" and "Attributes" elements:

Each attribute must have a name that is unique among all attributes attached to the same object:

Try to export a different attribute with an already existing name:

It is possible to overwrite existing attributes with "AppendMode" set to "Overwrite":

"Datasets" is the default export element. Data format and dimensions are automatically inferred from the expression:

Export expressions into different datasets, each of which can have a full path:

Inspect the structure of the HDF5 file:

Export a dataset with a custom data format:

Export a dataset with an attribute:

Create a scalar dataset with a single integer:

Create an array of integer numbers:

Export an array of real numbers:

Export a numeric array with complex numbers:

Note that complex numbers are exported to a compound dataset:

Use the "ComplexKeys" option to get complex numbers back:

Create a dataset with strings:

A ByteArray is stored as a "ByteArray" type (also called the opaque type in HDF5):

Associations with string keys are exported as elements of a compound type:

Create a dataset of initial size 2×2 that can later be extended to 10 rows and arbitrarily many columns:

Overwrite the first row with a list of 5 integers. This will extend the dataset to 5 columns:

Use the "SpaceSelection" subelement to overwrite the third and fourth columns:

Create a 3×4 dataset that can be arbitrarily extended:

Append a 3×3 array. This can only be done along the first dimension and Export will automatically detect that:

Sometimes data dimensions do not allow for automatic extensions of the dataset:

In this case, "SpaceSelection" can be specified manually:

HDF5 files always have a root group (with path "/"):

Export multiple groups by giving a list of paths:

Groups can have links to other groups or datasets:

Soft link names cannot contain the special character "/":

Soft link target must be a valid path, without "." or "..":

If a soft link target is missing, the link becomes a dangling link:

Create a file with two groups, a dataset and a hard link from one group to the dataset:

A hard link pointing to a nonexistent location cannot be added:

Create a new dataset under "/A/newDset":

Try to redirect the "newDset" link to point to group "B":

It is only possible with "Overwrite" mode:

Now the access to the second dataset is irreversibly lost. This is a resource leak as the dataset still occupies space in the file.

As with soft links, hard link name is always relative to the group path and must consist of exactly one path element:

The hard link target must be a valid path, without "." or "..":

Export a simple type to the file:

Append a compound named data type to the same file:

Use the previously exported type when exporting a dataset:

Import data format and dimensions of the dataset:

Inspect exported data:

Named datatypes can carry attributes:

HDF5 has no built-in type for complex numbers. Usually they are stored in a compound type:

Specify keys to be interpreted as real and imaginary parts of a complex number:

Import three points from a dataset:

This would be equivalent to but more efficient than extracting parts after importing the whole dataset:

Import a range of data from a dataset using spans:

Use suboptions for specifying offset, stride, and block:

When appending data to an existing file using OverwriteTarget"Append", the export behavior for appending data can be specified using the "AppendMode" option. By default, "AppendMode""Extend" is used.

Create a simple file:

Add a new group:

Append a new dataset:

Append some attributes to "gr1/ds1" and a hard link from "gr1" to "gr2":

"AppendMode""Extend" does not allow for modifying existing attributes or links:

With "AppendMode""Overwrite", it is possible to overwrite existing objects and add new ones:

With "AppendMode""Overwrite", it is possible to modify data in existing datasets as long as data format and dimensions match:

To append new objects to the file with the guarantee that no existing structures in the file will be modified, use "AppendMode""Preserve":

HDF5 allows you to choose the byte ordering. Create a big-endian file using ByteOrdering-1:

Create a little-endian file:

The two files are actually different:

Import will work correctly independently of the byte ordering:

By default, complex numbers are exported to a compound type using "Re" and "Im" keys:

Specify different keys:

To import the data as complex numbers, specify the keys in Import:

Keys must be different:

By default, with OverwriteTargetTrue, every call to Export writes a new file:

With OverwriteTargetFalse, the call to Export will fail if the output file already exists:

Export to certain formats, e.g. HDF5, supports the setting OverwriteTarget"Append", which makes Export act on the output file if it already exists, instead of overwriting it: