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GeneratePythonFitScript v1

Summary

An algorithm to generate a Python script file for performing a sequential or simultaneous fit.

See Also

Fit, GeneratePythonScript

Properties

Name

Direction

Type

Default

Description

InputWorkspaces

Input

str list

Mandatory

A list of workspace names to be fitted. The workspace name at index i in the list corresponds with the ‘WorkspaceIndices’, ‘StartXs’ and ‘EndXs’ properties.

WorkspaceIndices

Input

unsigned int list

A list of workspace indices to be fitted. The workspace index at index i in the list will correspond to the input workspace at index i.

StartXs

Input

dbl list

A list of start X’s to be used for the fitting. The Start X at index i will correspond to the input workspace at index i.

EndXs

Input

dbl list

A list of end X’s to be used for the fitting. The End X at index i will correspond to the input workspace at index i.

FittingType

Input

string

Sequential

The type of fitting to generate a python script for (Sequential or Simultaneous). Allowed values: [‘Sequential’, ‘Simultaneous’]

Function

Input

Function

Mandatory

The function to use for the fitting. This should be a single domain function if the Python script will be for sequential fitting, or a MultiDomainFunction if the Python script is for simultaneous fitting.

MaxIterations

Input

number

500

The MaxIterations to be passed to the Fit algorithm in the Python script.

Minimizer

Input

string

Levenberg-Marquardt

The Minimizer to be passed to the Fit algorithm in the Python script. Allowed values: [‘BFGS’, ‘Conjugate gradient (Fletcher-Reeves imp.)’, ‘Conjugate gradient (Polak-Ribiere imp.)’, ‘Damped GaussNewton’, ‘FABADA’, ‘Levenberg-Marquardt’, ‘Levenberg-MarquardtMD’, ‘Simplex’, ‘SteepestDescent’, ‘Trust Region’]

CostFunction

Input

string

Least squares

The CostFunction to be passed to the Fit algorithm in the Python script. Allowed values: [‘Least squares’, ‘Poisson’, ‘Rwp’, ‘Unweighted least squares’]

EvaluationType

Input

string

CentrePoint

The EvaluationType to be passed to the Fit algorithm in the Python script. Allowed values: [‘CentrePoint’, ‘Histogram’]

OutputBaseName

Input

string

Output_Fit

The OutputBaseName is the base output name to use for the resulting Fit workspaces.

PlotOutput

Input

boolean

True

If true, code used for plotting the results of a fit will be generated and added to the python script.

Filepath

Input

string

The name of the Python fit script which will be generated and saved in the selected location. Allowed extensions: [‘.py’]

ScriptText

Output

string

Description

This algorithm can be used to generate a python script used for sequential or simultaneous fitting. The generated python script is intended to be a generic example for how you can perform a fit in Mantid, and can easily be adapted for specific needs. This algorithm is used by the Fit Script Generator interface.

Usage

Example - generate a python script used for sequential fitting:

ws1 = CreateSampleWorkspace()
ws2 = CreateSampleWorkspace()

function = \
"name=GausOsc,A=0.2,Sigma=0.2,Frequency=1,Phi=0"

# If you want to save the python script to a file then specify the Filepath property
script_text = GeneratePythonFitScript(InputWorkspaces=["ws1", "ws1", "ws2", "ws2"], WorkspaceIndices=[0, 1, 0, 1],
                                      StartXs=[0.0, 0.0, 0.0, 0.0], EndXs=[20000.0, 20000.0, 20000.0, 20000.0],
                                      FittingType="Sequential", Function=function, MaxIterations=500,
                                      Minimizer="Levenberg-Marquardt", OutputBaseName="Output_Fit")

print(script_text)

Output:

# A python script generated to perform a sequential fit
from mantid.api import AnalysisDataService
from mantid.simpleapi import Fit, GroupWorkspaces
import matplotlib.pyplot as plt

# List of tuples [ (workspace_name, workspace_index, start_x, end_x) ]
input_data = [
    ("ws1", 0, 0.000000, 20000.000000),
    ("ws1", 1, 0.000000, 20000.000000),
    ("ws2", 0, 0.000000, 20000.000000),
    ("ws2", 1, 0.000000, 20000.000000)
]

# Fit function as a string
function = \
    "name=GausOsc,A=0.2,Sigma=0.2,Frequency=1,Phi=0"

# Fitting options
max_iterations = 500
minimizer = "Levenberg-Marquardt"
cost_function = "Least squares"
evaluation_type = "CentrePoint"
output_base_name = "Output_Fit"

# Perform a sequential fit
output_workspaces, parameter_tables, normalised_matrices = [], [], []
for domain_data in input_data:
    output_name = output_base_name + domain_data[0] + str(domain_data[1])

    fit_output = Fit(Function=function, InputWorkspace=domain_data[0], WorkspaceIndex=domain_data[1],
                     StartX=domain_data[2], EndX=domain_data[3], MaxIterations=max_iterations,
                     Minimizer=minimizer, CostFunction=cost_function, EvaluationType=evaluation_type,
                     Output=output_name)

    output_workspaces.append(output_name + "_Workspace")
    parameter_tables.append(output_name + "_Parameters")
    normalised_matrices.append(output_name + "_NormalisedCovarianceMatrix")

    # Use the parameters in the previous function as the start parameters of the next fit
    function = fit_output.Function

# Group the output workspaces from the sequential fit
GroupWorkspaces(InputWorkspaces=output_workspaces, OutputWorkspace=output_base_name + "Workspaces")
GroupWorkspaces(InputWorkspaces=parameter_tables, OutputWorkspace=output_base_name + "Parameters")
GroupWorkspaces(InputWorkspaces=normalised_matrices, OutputWorkspace=output_base_name + "NormalisedCovarianceMatrices")

# Plot the results of the fit
fig, axes = plt.subplots(nrows=2,
                         ncols=len(output_workspaces),
                         sharex=True,
                         gridspec_kw={"height_ratios": [2, 1]},
                         subplot_kw={"projection": "mantid"})

for i, workspace_name in enumerate(output_workspaces):
    workspace = AnalysisDataService.retrieve(workspace_name)
    axes[0, i].errorbar(workspace, "rs", wkspIndex=0, label="Data", markersize=2)
    axes[0, i].errorbar(workspace, "b-", wkspIndex=1, label="Fit")
    axes[0, i].set_title(workspace_name)
    axes[0, i].set_xlabel("")
    axes[0, i].tick_params(axis="both", direction="in")
    axes[0, i].legend()

    axes[1, i].errorbar(workspace, "ko", wkspIndex=2, markersize=2)
    axes[1, i].set_ylabel("Difference")
    axes[1, i].tick_params(axis="both", direction="in")

fig.subplots_adjust(hspace=0)
fig.show()

Example - generate a python script used for simultaneous fitting:

ws1 = CreateSampleWorkspace()
ws2 = CreateSampleWorkspace()

function = \
"composite=MultiDomainFunction,NumDeriv=true;" \
"name=GausOsc,A=0.2,Sigma=0.2,Frequency=1,Phi=0,$domains=i;" \
"name=GausOsc,A=0.2,Sigma=0.2,Frequency=1,Phi=0,$domains=i;" \
"name=GausOsc,A=0.2,Sigma=0.2,Frequency=1,Phi=0,$domains=i;" \
"name=GausOsc,A=0.2,Sigma=0.2,Frequency=1,Phi=0,$domains=i;" \
"ties=(f2.Frequency=f3.Frequency,f1.Frequency=f3.Frequency,f0.Frequency=f3.Frequency)"

# If you want to save the python script to a file then specify the Filepath property
script_text = GeneratePythonFitScript(InputWorkspaces=["ws1", "ws1", "ws2", "ws2"], WorkspaceIndices=[0, 1, 0, 1],
                                      StartXs=[0.0, 0.0, 0.0, 0.0], EndXs=[20000.0, 20000.0, 20000.0, 20000.0],
                                      FittingType="Simultaneous", Function=function, MaxIterations=500,
                                      Minimizer="Levenberg-Marquardt", OutputBaseName="Output_Fit")

print(script_text)

Output:

# A python script generated to perform a simultaneous fit
from mantid.api import AnalysisDataService
from mantid.simpleapi import Fit
import matplotlib.pyplot as plt

# List of tuples [ (workspace_name, workspace_index, start_x, end_x) ]
input_data = [
    ("ws1", 0, 0.000000, 20000.000000),
    ("ws1", 1, 0.000000, 20000.000000),
    ("ws2", 0, 0.000000, 20000.000000),
    ("ws2", 1, 0.000000, 20000.000000)
]

# Fit function as a string
function = \
    "composite=MultiDomainFunction,NumDeriv=true;" \
    "name=GausOsc,A=0.2,Sigma=0.2,Frequency=1,Phi=0,$domains=i;" \
    "name=GausOsc,A=0.2,Sigma=0.2,Frequency=1,Phi=0,$domains=i;" \
    "name=GausOsc,A=0.2,Sigma=0.2,Frequency=1,Phi=0,$domains=i;" \
    "name=GausOsc,A=0.2,Sigma=0.2,Frequency=1,Phi=0,$domains=i;" \
    "ties=(f2.Frequency=f3.Frequency,f1.Frequency=f3.Frequency,f0.Frequency=f3.Frequency)"

# Fitting options
max_iterations = 500
minimizer = "Levenberg-Marquardt"
cost_function = "Least squares"
evaluation_type = "CentrePoint"
output_base_name = "Output_Fit"

# Perform a simultaneous fit
input_workspaces = [domain[0] for domain in input_data]
domain_data = [domain[1:] for domain in input_data]

fit_output = \
    Fit(Function=function,
        InputWorkspace=input_workspaces[0], WorkspaceIndex=domain_data[0][0], StartX=domain_data[0][1], EndX=domain_data[0][2],
        InputWorkspace_1=input_workspaces[1], WorkspaceIndex_1=domain_data[1][0], StartX_1=domain_data[1][1], EndX_1=domain_data[1][2],
        InputWorkspace_2=input_workspaces[2], WorkspaceIndex_2=domain_data[2][0], StartX_2=domain_data[2][1], EndX_2=domain_data[2][2],
        InputWorkspace_3=input_workspaces[3], WorkspaceIndex_3=domain_data[3][0], StartX_3=domain_data[3][1], EndX_3=domain_data[3][2],
        MaxIterations=max_iterations, Minimizer=minimizer, CostFunction=cost_function,
        EvaluationType=evaluation_type, Output=output_base_name)

output_workspaces = []
for i in range(len(input_workspaces)):
    output_workspaces.append(output_base_name + "_Workspace_" + str(i))

# Plot the results of the fit
fig, axes = plt.subplots(nrows=2,
                         ncols=len(output_workspaces),
                         sharex=True,
                         gridspec_kw={"height_ratios": [2, 1]},
                         subplot_kw={"projection": "mantid"})

for i, workspace_name in enumerate(output_workspaces):
    workspace = AnalysisDataService.retrieve(workspace_name)
    axes[0, i].errorbar(workspace, "rs", wkspIndex=0, label="Data", markersize=2)
    axes[0, i].errorbar(workspace, "b-", wkspIndex=1, label="Fit")
    axes[0, i].set_title(workspace_name)
    axes[0, i].set_xlabel("")
    axes[0, i].tick_params(axis="both", direction="in")
    axes[0, i].legend()

    axes[1, i].errorbar(workspace, "ko", wkspIndex=2, markersize=2)
    axes[1, i].set_ylabel("Difference")
    axes[1, i].tick_params(axis="both", direction="in")

fig.subplots_adjust(hspace=0)
fig.show()

Categories: AlgorithmIndex | Utility\Python

Source

C++ header: GeneratePythonFitScript.h

C++ source: GeneratePythonFitScript.cpp