SaveNexusProcessed dialog.
Table of Contents
The SaveNexusProcessed algorithm will write the given Mantid workspace to a Nexus file. SaveNexusProcessed may be invoked by SaveNexus.
| 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. |
The algorithm SaveNexusProcessed will write a Nexus data file from the named workspace. This can later be loaded using LoadNexusProcessed v1.
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.
TimeSeriesProperty data within the workspace will be saved as NXlog sections in the Nexus file. Only floating point logs are stored and loaded at present.
This algorithm will save EventWorkspaces with full event data, unless you uncheck PreserveEvents, in which case the histogram version of the workspace is saved.
Optionally, you can check CompressNexus, which will compress the event data. Warning! This can be very slow, and only gives approx. 40% compression because event data is typically denser than histogram data. CompressNexus is off by default.
Example - a basic example using SaveNexusProcessed.
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 additonal 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()))
Output:
True
Saved workspace has 200 spectra
Categories: Algorithms | DataHandling\Nexus
C++ source: SaveNexusProcessed.cpp (last modified: 2018-01-19)
C++ header: SaveNexusProcessed.h (last modified: 2018-01-19)