dump method for diffraction_objects with test

Author: sbillinge

Diff for: src/diffpy/utils/scattering_objects/diffraction_objects.py

@@ -14,7 +14,7 @@ class Diffraction_object():
     def __init__(self, name='', wavelength=None):
         self.name = name
         self.wavelength = wavelength
-        self.scat_quantities = {}
+        self.scat_quantity = ""
         self.on_q = [np.empty(1), np.empty(1)]
         self.on_tth = [np.empty(1), np.empty(1)]
         self.on_d = [np.empty(1), np.empty(1)]
@@ -401,3 +401,21 @@ def on_xtype(self, xtype):
         elif xtype.lower() in DQUANTITIES:
             return self.on_d
         pass
+
+    def dump(self, filepath, xtype=None):
+        if xtype is None:
+            xtype = " q"
+        if xtype == "q":
+            data_to_save = np.column_stack((self.on_q[0], self.on_q[1]))
+        elif xtype == "tth":
+            data_to_save = np.column_stack((self.on_tth[0], self.on_tth[1]))
+        else:
+            print(f"WARNING: cannot handle the xtype '{xtype}'")
+
+        with open(filepath, 'w') as f:
+            f.write(f"[Diffraction_object]\nname = {self.name}\nwavelength = {self.wavelength}\n"
+                    f"scat_quantity = {self.scat_quantity}\n")
+            for key, value in self.metadata.items():
+                f.write(f"{key} = {value}\n")
+            f.write("\n#### start data\n")
+            np.savetxt(f, data_to_save, delimiter=" ")

Diff for: src/diffpy/utils/tests/test_diffraction_objects.py

@@ -0,0 +1,25 @@
+import numpy as np
+from pathlib import Path
+from diffpy.utils.scattering_objects.diffraction_objects import Diffraction_object
+
+def test_dump(tmp_path):
+	x, y = np.linspace(0, 10, 11), np.linspace(0, 10, 11)
+	directory = Path(tmp_path)
+	file = directory / "testfile"
+	test = Diffraction_object()
+	test.wavelength = 1.54
+	test.name = "test"
+	test.scat_quantity = "x-ray"
+	test.insert_scattering_quantity(x, y, "q", metadata={"thing1": 1, "thing2": "thing2"})
+	test.dump(file, "q")
+	with open(file, "r") as f:
+		actual = f.read()
+	expected = ("[Diffraction_object]\nname = test\nwavelength = 1.54\nscat_quantity = x-ray\nthing1 = 1\n"
+				"thing2 = thing2\n\n#### start data\n0.000000000000000000e+00 0.000000000000000000e+00\n"
+				"1.000000000000000000e+00 1.000000000000000000e+00\n2.000000000000000000e+00 2.000000000000000000e+00\n"
+				"3.000000000000000000e+00 3.000000000000000000e+00\n4.000000000000000000e+00 4.000000000000000000e+00\n"
+				"5.000000000000000000e+00 5.000000000000000000e+00\n"
+				"6.000000000000000000e+00 6.000000000000000000e+00\n7.000000000000000000e+00 7.000000000000000000e+00\n"
+				"8.000000000000000000e+00 8.000000000000000000e+00\n9.000000000000000000e+00 9.000000000000000000e+00\n"
+				"1.000000000000000000e+01 1.000000000000000000e+01\n")
+	assert actual == expected