Merge pull request #43 from jmborr/42_tabulated_resolution

Tabulated resolution function

HISTORY.rst

@@ -5,6 +5,7 @@ History
 0.2.0 ()
 --------
 * Load Mantid Nexus data (PR #38)
+* Tabulated resolution model (PR #43)
 
 0.1.0 (2017-12-13)
 ------------------

docs/qef/models/models.rst

@@ -7,6 +7,7 @@ Models
    :maxdepth: 1
 
    deltadirac
+   resolution
    strexpft
    tabulatedmodel
    teixeira

docs/qef/models/resolution.rst

@@ -0,0 +1,7 @@
+Resolution models
+=================
+
+.. automodule:: qef.models.resolution
+    :members:
+    :undoc-members:
+    :show-inheritance:

qef/models/resolution.py

@@ -0,0 +1,21 @@
+from __future__ import (absolute_import, division, print_function)
+
+from qef.models.tabulatedmodel import TabulatedModel
+
+
+class TabulatedResolutionModel(TabulatedModel):
+    r"""Interpolator of resolution data with no fit parameters
+
+    Parameters
+    ----------
+    xs: :class:`~numpy:numpy.ndarray`
+        given domain of the function, energy
+
+    ys: :class:`~numpy:numpy.ndarray`
+        given domain of the function, intensity
+    """
+
+    def __init__(self, xs, ys, *args, **kwargs):
+        super(TabulatedResolutionModel, self).__init__(xs, ys, *args, **kwargs)
+        self.set_param_hint('amplitude', value=1.0, vary=False)
+        self.set_param_hint('center', value=0.0, vary=False)

qef/models/tabulatedmodel.py

@@ -1,8 +1,10 @@
+from __future__ import (absolute_import, division, print_function)
+
 from scipy.interpolate import interp1d
 from lmfit import Model, models
 
 
-class TabulatedModel (Model):
+class TabulatedModel(Model):
     """fitting the tabulated Model to some arbitrary points
 
         Parameters
@@ -13,12 +15,9 @@ class TabulatedModel (Model):
         ys: :class:`~numpy:numpy.ndarray`
             given domain of the function, intensity
 
-        amplitude : float
-            peak intensity of the curve
-
-        center : float
-            position of the peak
-
+        Fitting parameters:
+            - rescaling factor ``amplitude``
+            - shift along the X-axis ``center``
     """
 
     def __init__(self, xs, ys, *args, **kwargs):

tests/models/test_resolution.py

@@ -0,0 +1,29 @@
+from __future__ import (absolute_import, division, print_function)
+
+import os
+import pytest
+import numpy as np
+from lmfit.lineshapes import lorentzian
+
+from qef.models.resolution import TabulatedResolutionModel
+
+
+def test_tabulated_resolution():
+    x_sim = np.arange(-1.0, 1.0, 0.0003)  # energy domain, in meV
+    y_sim = lorentzian(x_sim, amplitude=1, center=0, sigma=0.042)
+    intensity = 42.0
+    peak_center = 0.0002
+    x_exp = np.arange(-0.1, 0.5, 0.0004)
+    y_exp = lorentzian(x_exp, amplitude=intensity, center=peak_center,
+                       sigma=0.042)
+
+    model = TabulatedResolutionModel(x_sim, y_sim)
+    params = model.make_params()
+    fit = model.fit(y_exp, params, x=x_exp)
+
+    assert abs(fit.best_values['amplitude'] - 1.0) < 0.0001
+    assert abs(fit.best_values['center'] - 0.0) < 0.0001
+
+
+if __name__ == '__main__':
+    pytest.main([os.path.abspath(__file__)])