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SaveNexusProcessed v1¶

Summary ¶

The SaveNexusProcessed algorithm will write the given Mantid workspace to a Nexus file. SaveNexusProcessed may be invoked by SaveNexus.

Properties ¶

Name	Direction	Type	Default	Description
InputWorkspace	Input	Workspace	Mandatory	Name of the workspace to be saved
Filename	Input	string	Mandatory	The name of the Nexus file to write, as a full or relative path. Allowed extensions: [‘.nxs’, ‘.nx5’, ‘.xml’]
Title	Input	string		A title to describe the saved workspace
WorkspaceIndexMin	Input	number	0	Index number of first spectrum to write, only for single period data.
WorkspaceIndexMax	Input	number	Optional	Index of last spectrum to write, only for single period data.
WorkspaceIndexList	Input	int list		List of spectrum numbers to read, only for single period data.
Append	Input	boolean	False	Determines whether .nxs file needs to be over written or appended
PreserveEvents	Input	boolean	True	For EventWorkspaces, preserve the events when saving (default). If false, will save the 2D histogram version of the workspace with the current binning parameters.
CompressNexus	Input	boolean	False	For EventWorkspaces, compress the Nexus data field (default False). This will make smaller files but takes much longer.

Description ¶

The algorithm SaveNexusProcessed will write a Nexus data file from the named workspace. This can later be loaded using LoadNexusProcessed v2.

The file name can be an absolute or relative path and should have the extension .nxs, .nx5 or .xml. Warning - using XML format can be extremely slow for large data sets and generate very large files. Both the extensions nxs and nx5 will generate HDF5 files.

The optional parameters can be used to control which spectra are saved into the file. If WorkspaceIndexMin and WorkspaceIndexMax are given, then only that range to data will be loaded.

A Mantid Nexus file may contain several workspace entries each labelled with an integer starting at 1. If the file already contains n workspaces, the new one will be labelled n+1.

import os

ws = CreateSampleWorkspace()
file_name = "myworkspace.nxs"
path = os.path.join(os.path.expanduser("~"), file_name)
SaveNexusProcessed(ws, path)

print(os.path.isfile(path))

Output:

True

Example - an example using SaveNexusProcessed with additional options.

import os

ws = CreateSampleWorkspace()
file_name = "myworkspace.nxs"
path = os.path.join(os.path.expanduser("~"), file_name)
SaveNexusProcessed(ws, path, Title="MyWorkspace", WorkspaceIndexMin=0, WorkspaceIndexMax=9)

print(os.path.isfile(path))

ws = Load(path)
print("Saved workspace has {} spectra".format(ws.getNumberHistograms()))

Output:

True
Saved workspace has 10 spectra

Example - an example using SaveNexusProcessed to save an Event workspace.

import os

ws = CreateSampleWorkspace("Event")
file_name = "myworkspace.nxs"
path = os.path.join(os.path.expanduser("~"), file_name)
SaveNexusProcessed(ws, path, CompressNexus=True, PreserveEvents=True)

print(os.path.isfile(path))

ws = Load(path)
print("Saved workspace has {} spectra".format(ws.getNumberHistograms()))