Group (H5G)

Organization of objects in file

Description

Use the MATLAB^® HDF5 group interface, H5G, to create, open, close, and access information about groups in an HDF5 file.

Groups are structures that contain other objects in the HDF5 file. Typically, groups contain other groups and datasets.

Functions

H5G.close

Close group

H5G.close(groupID) releases resources used by the group identifier specified by groupID. The identifier groupID was returned by either H5G.create or H5G.open.

H5G.create

Create group

groupID = H5G.create(locID,groupname,size) creates a new group with the name specified by groupname at the location specified by locID. This syntax corresponds to the H5Gcreate interface in version 1.6 of the HDF5 C library.

groupID = H5G.create(locID,groupname,lcplID,gcplID,gaplID) creates a new group with additional property list, specified by lcplID, gcplID, and gaplID. This syntax corresponds to the H5Gcreate interface in version 1.8 of the HDF5 C library.

 Details

Input Arguments

• locID — File or group identifier.

• groupname — Group name.

• size — Number of bytes to reserve for the names that will appear in the group.

• lcplID — Link creation property list identifier.

• gcplID — Group creation property list identifier.

• gaplID — Group access property list identifier.

Output Arguments

• groupID — Identifier of created group.

H5G.flush

Flush all data buffers to disk

H5G.flush(groupID) causes all buffers associated with a group specified by groupID to be immediately flushed to disk without removing the data from the cache.

H5G.get_create_plist

Group creation property list

gcplID = H5G.get_create_plist(groupID) returns an identifier for the group creation property list associated with the group specified by groupID.

H5G.get_info

Information about group

info = H5G.get_info(groupID) returns information about the group specified by groupID.

H5G.open

Open specified group

groupID = H5G.open(locID,groupname) opens the group specified by groupname at the location specified by the file or group identifier locID. This function corresponds to the H5Gopen interface in version 1.6 of the HDF5 C library.

groupID = H5G.open(locID,groupname,gaplID) opens the group with an additional group access property list specified by gaplID. This function corresponds to the H5Gopen interface in version 1.8 of the HDF5 C library.

H5G.refresh

Clear and reload all data buffers

H5G.refresh(groupID) causes all buffers associated with a group specified by groupID to be cleared and immediately reloaded with updated contents from disk.

Examples

Create New Group in HDF5 File

Create an HDF5 file "myfile.h5" with a group "my_group" with default property list settings.

fid = H5F.create("myfile.h5");
plist = "H5P_DEFAULT";
gid = H5G.create(fid,"my_group",plist,plist,plist);
H5G.close(gid);
H5F.close(fid);

Open Group in HDF5 File

fid = H5F.open("example.h5");
gid = H5G.open(fid,"/g2");
info = H5G.get_info(gid);
H5G.close(gid);
H5F.close(fid);

Version History

Introduced before R2006a

R2021b: Flush and refresh buffers associated with a group

You can use H5G.flush to flush the buffers associated with a group to disk and H5G.refresh to clear the buffer associated with a group and reload with updated contents from disk.