Addded string-to-kernel helper functions to facilitate GPs from Dicts

flare/kernels.py

@@ -869,3 +869,34 @@ def triplet_force_en_kernel(ci1, ci2, ri1, ri2, ri3, rj1, rj2, rj3,
     print(kern_finite_diff)
     print(kern_analytical)
     assert(np.isclose(kern_finite_diff, kern_analytical, atol=tol))
+
+_str_to_kernel = {'two_body': two_body,
+                  'two_body_en': two_body_en,
+                  'two_body_force_en': two_body_force_en,
+                  'three_body': three_body,
+                  'three_body_en': three_body_en,
+                  'three_body_force_en': three_body_force_en,
+                  'two_plus_three_body': two_plus_three_body,
+                  'two_plus_three_en': two_plus_three_en,
+                  'two_plus_three_force_en': two_plus_three_force_en
+                  }
+
+
+def str_to_kernel(string: str, include_grad: bool=False):
+
+    if string not in _str_to_kernel.keys():
+        raise ValueError("Kernel {} not found in list of available "
+                         "kernels{}:".format(string,_str_to_kernel.keys()))
+
+    if not include_grad:
+        return _str_to_kernel[string]
+    else:
+        if 'two' in string and 'three' in string:
+            return _str_to_kernel[string], two_plus_three_body_grad
+        elif 'two' in string and 'three' not in string:
+            return _str_to_kernel[string], two_body_grad
+        elif 'two' not in string and 'three' in string:
+            return _str_to_kernel[string], three_body_grad
+        else:
+            raise ValueError("Gradient callable for {} not found".format(
+                string))