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CreateMDWorkspace dialog.
Table of Contents
| Name | Direction | Type | Default | Description |
|---|---|---|---|---|
| Dimensions | Input | number | 1 | Number of dimensions that the workspace will have. |
| EventType | Input | string | MDLeanEvent | Which underlying data type will event take. Allowed values: [‘MDEvent’, ‘MDLeanEvent’] |
| Extents | Input | dbl list | A comma separated list of min, max for each dimension, specifying the extents of each dimension. | |
| Names | Input | str list | A comma separated list of the name of each dimension. | |
| Units | Input | str list | A comma separated list of the units of each dimension. | |
| Frames | Input | str list | A comma separated list of the frames of each dimension. The frames can be General Frame: Any frame which is not a Q-based frame. QLab: Wave-vector converted into the lab frame. QSample: Wave-vector converted into the frame of the sample. HKL: Wave-vector converted into the crystal’s HKL indices. Note if nothing is specified then the General Frame is being selected. Also note that if you select a frame then this might override your unit selection if it is not compatible with the frame. | |
| SplitInto | Input | int list | 5 | A comma separated list of into how many sub-grid elements each dimension should split; or just one to split into the same number for all dimensions. Default 5. |
| SplitThreshold | Input | number | 1000 | How many events in a box before it should be split. Default 1000. |
| MaxRecursionDepth | Input | number | 5 | How many levels of box splitting recursion are allowed. The smallest box will have each side length \(l = (extents) / (SplitInto^{MaxRecursionDepth}).\) Default 5. |
| MinRecursionDepth | Input | number | 0 | Optional. If specified, then all the boxes will be split to this minimum recursion depth. 0 = no splitting, 1 = one level of splitting, etc. Be careful using this since it can quickly create a huge number of boxes = (SplitInto ^ (MinRercursionDepth * NumDimensions)). |
| OutputWorkspace | Output | Workspace | Mandatory | Name of the output MDEventWorkspace. |
| Filename | Input | string | Optional: to use a file as the back end, give the path to the file to save. Allowed extensions: [‘.nxs’] | |
| Memory | Input | number | -1 | If Filename is specified to use a file back end: The amount of memory (in MB) to allocate to the in-memory cache. If not specified, a default of 40% of free physical memory is used. |
This algorithm creates an empty MDEventWorkspace from scratch. The workspace can have any number of dimensions (up to ~20). Each dimension must have its name, units, extents specified as comma-spearated string.
The SplitInto parameter determines how splitting of dense boxes will be performed. For example, if SplitInto=5 and the number of dimensions is 3, then each box will get split into 5x5x5 sub-boxes.
The SplitThreshold parameter determines how many events to keep in a box before splitting it into sub-boxes. This value can significantly affect performance/memory use! Too many events per box will mean unnecessary iteration and a slowdown in general. Too few events per box will waste memory with the overhead of boxes.
You can create a file-backed MDEventWorkspace by specifying the Filename and Memory parameters.
Example
mdws = CreateMDWorkspace(Dimensions=3, Extents='-10,10,-10,10,-10,10', Names='A,B,C', Units='U,U,U')
print("mdws is a " + mdws.id())
print("with {0} dimensions:".format(mdws.getNumDims()))
for i in range (mdws.getNumDims()):
print(mdws.getDimension(i).name)
Output:
mdws is a MDEventWorkspace<MDLeanEvent,3>
with 3 dimensions:
A
B
C
Categories: AlgorithmIndex | MDAlgorithms\Creation
C++ header: CreateMDWorkspace.h (last modified: 2021-03-31)
C++ source: CreateMDWorkspace.cpp (last modified: 2021-05-24)