funct/test: fixing squeeze function and test

Author: Luiskitsu

news/morphsqueeze.rst

@@ -5,7 +5,9 @@
 **Changed:**
 
 * Added cubic and quadratic terms, as well as
-* squeeze_1 and squeeze_2 parameters
+* squeeze_1 and squeeze_2 parameters.
+* I was not keeping the y-axis constant and
+* corrected for it
 
 **Deprecated:**
 
@@ -17,7 +19,7 @@
 
 **Fixed:**
 
-* <news item>
+* I was not keeping the y-values constant, fixed now
 
 **Security:**
 

src/diffpy/morph/morphs/morphsqueeze.py

@@ -1,10 +1,8 @@
 """class MorphSqueeze -- apply a non-linear squeeze to the morph.
 This morph non-linearly adjusts the x-coordinates.
-The y-values are then recomputed by interpolating the original data.
+The y-values are the same as initial, just on a new grid.
 """
 
-import numpy as np
-
 from diffpy.morph.morphs.morph import LABEL_GR, LABEL_RA, Morph
 
 
@@ -48,8 +46,8 @@ def morph(self, x_morph, y_morph, x_target, y_target):
 
         self.x_morph_out = new_x
 
-        # Interpolate the y-values at the new x positions.
-        self.y_morph_out = np.interp(new_x, self.x_morph_in, self.y_morph_in)
+        # The y-axis should be the same
+        self.y_morph_out = self.y_morph_in
 
         return self.xyallout
 

tests/test_morphsqueeze.py

@@ -53,11 +53,12 @@ def test_morph_with_squeeze(self, setup):
             + morph.squeeze_1 * self.x_morph**2
             + morph.squeeze_2 * self.x_morph**3
         )
-        expected_y = np.interp(expected_x, self.x_morph, self.y_morph)
+        expected_y = np.sin(self.x_morph)
 
-        # Allow for some tolerance because of numerical interpolation if used
         res = sum(np.fabs(expected_y - y_new))
-        assert res < 1
+        res2 = sum(np.fabs(expected_x - x_new))
+        assert res < 0.1
+        assert res2 < 0.1
 
 
 if __name__ == "__main__":