Changeset 74b0495 in sasmodels for example/simul_fit.py

Timestamp:

Oct 10, 2017 11:39:39 AM (7 years ago)

Author:

Paul Kienzle <pkienzle@…>

Branches:

master, core_shell_microgels, costrafo411, magnetic_model, ticket-1257-vesicle-product, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests

Children:

09141ff

Parents:

b76191e

Message:

update oriented sesans and simultaneous fit examples

File:

• example/simul_fit.py (modified) (2 diffs)

example/simul_fit.py

@@ -1 @@
-#!/usr/bin/env python
-# -*- coding: utf-8 -*-
-
-# To Sasview/documents/scripts
-
 from bumps.names import *
 from sasmodels.core import load_model
@@ -9 +4 @@
 from sasmodels.data import load_data, plot_data
 
+# latex data, same sample usans and sans
+# particles radius ~2300, uniform dispersity
+datasets = load_data('latex_smeared.xml', index='all')
+#[print(data) for data in datasets]
 
-""" IMPORT THE DATA USED """
-datafiles = ['latex_smeared_out_0.txt', 'latex_smeared_out_1.txt']
-datasets = [load_data(el) for el in datafiles]
+# A single sphere model to share between the datasets.  We will use
+# FreeVariables below to set the parameters that are independent between
+# the datasets.
+kernel = load_model('sphere')
+pars = dict(scale=0.01, background=0.0, sld=5.0, sld_solvent=0.0, radius=1500.,
+            #radius_pd=0.1, radius_pd_n=35,
+            )
+model = Model(kernel, **pars)
 
-for data in datasets:
-    data.qmin = 0.0
-    data.qmax = 10.0
+# radius and polydispersity (if any) are shared
+model.radius.range(0, inf)
+#model.radius_pd.range(0, 1)
 
-#sphere model
-kernel = load_model('sphere', dtype="single")
-pars = dict(scale=0.01, background=0.0, sld=1.0, sld_solvent=6.0, radius=1500.)
-model = Model(kernel, **pars)
-model.radius.range(0, inf)
-#model.background.range(-inf, inf)
-#model.scale.range(0, inf)
-model.sld.range(-inf, inf)
-model.sld_solvent.range(-inf, inf)
+# Contrast and dilution are the same for both measurements, but are not
+# separable with a single measurement (i.e., I(q) ~ F(q) contrast^2 Vf),
+# so fit one of scale, sld or solvent sld.  With absolute scaling from
+# data reduction, can use the same parameter for both datasets.
+model.scale.range(0, inf)
+#model.sld.range(-inf, inf)
+#model.sld_solvent.range(-inf, inf)
 
+# Background is different for sans and usans so set it as a free variable
+# in the model.
 free = FreeVariables(
-    names=[data.filename for data in datasets],
+    names=[data.run[0] for data in datasets],
     background=model.background,
-    scale=model.scale,
     )
 free.background.range(-inf, inf)
-free.scale.range(0, inf)
 
-M = [Experiment(data=data, model=model) for data in datasets]
+# Note: can access the parameters for the individual models using
+# free.background[0] and free.background[1], setting constraints or
+# ranges as appropriate.
+
+# For more complex systems where different datasets require independent models,
+# separate models can be defined, with parameters tied together using
+# constraint expressions.  For example, the following could be used to fit
+# data set 1 to spheres and data set 2 to cylinders of the same volume:
+#    model1 = Model(load_model('sphere'))
+#    model2 = Model(load_model('cylinder'))
+#    model1.sld = model2.sld
+#    model1.sld_solvent = model2.sld_solvent
+#    model1.scale = model2.scale
+#    # set cylinders and spheres to the same volume
+#    model1.radius = (3/4*model2.radius**2*model2.length)**(1/3)
+#    model1.background.range(0, 2)
+#    model2.background.range(0, 2)
+
+# Setup the experiments, sharing the same model across all datasets.
+M = [Experiment(data=data, model=model, name=data.run[0]) for data in datasets]
 
 problem = FitProblem(M, freevars=free)
-
-print(problem._parameters)