CreateUserDefinedBackground v1¶

CreateUserDefinedBackground dialog.

Table of Contents

Summary
Properties
Description
- Typical use case
Usage
Source

Summary ¶

Creates a workspace of background data from a user-supplied set of points. This workspace can then be subtracted from the original data.

Properties ¶

Name	Direction	Type	Default	Description
InputWorkspace	Input	MatrixWorkspace	Mandatory	Input workspace containing data and background
BackgroundPoints	Input	TableWorkspace	Mandatory	Table containing user-defined background points
OutputBackgroundWorkspace	Output	MatrixWorkspace	Mandatory	Workspace containing background to be subtracted

Given an input workspace containing data with a background and a table of user-selected points defining the background, creates a new workspace containing background data that can be subtracted from the original data.

The background is constructed using linear interpolation at the same X values as the input workspace.

Typical use case ¶

Spectrum has several peaks on top of a large, irregularly shaped background.
Plot spectrum and use Data > Draw Data Points in MantidPlot to define the background. Clicking anywhere outside of the graph will show a table with the points defined by clicking.
Convert table to a TableWorkspace (Table > Convert to TableWorkspace)
Run this algorithm, giving it the original data and the background table. It will return a workspace filled with background data.
Use Minus v1 to subtract the returned workspace from the original data workspace.

Usage ¶

Example - CreateUserDefinedBackground

# Create data: background + peak
dataX = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
background = [0, 5, 10, 15, 20, 25, 30, 35, 40, 45]
peak = [0, 1, 4, 1, 0, 0, 0, 0, 0, 0]
dataY = [a + b for a, b in zip(background, peak)]
dataWS = CreateWorkspace(dataX, dataY)

# Create table of user-supplied background points
# In real use this would be done via the GUI
background_points = CreateEmptyTableWorkspace()
background_points.addColumn("double", "X", 1)
background_points.addColumn("double", "Y", 2)
for i in range(10):
   background_points.addRow([dataX[i], background[i]])

# Create background workspace and subtract it from data
backgroundWS = CreateUserDefinedBackground(InputWorkspace=dataWS, BackgroundPoints=background_points)
peakWS = Minus(dataWS, backgroundWS)


# Check that workspace matches expected peak
expected = CreateWorkspace(dataX, peak)
result, messages = CompareWorkspaces(peakWS, expected)
print "Workspaces match:", result