Add handling of pure magnetic (B) fields read from CST ASCII data.

pmd_beamphysics/interfaces/cst.py

@@ -23,13 +23,16 @@ def get_scale(unit):
         The scaling factor corresponding to the unit.
         - 1e-3 for millimeters ('[mm]')
         - 1 for volts per meter ('[V/m]')
+        - 1 for Tesla ('[T]')
         - mu0 (vacuum permeability) for amperes per meter ('[A/m]')
     """
 
     if unit == "[mm]":
         return 1e-3
     elif unit == "[V/m]":
         return 1
+    elif unit == "[T]":
+        return 1
     elif unit == "[A/m]":
         return mu0
 
@@ -63,9 +66,15 @@ def get_vec(x):
     sx = set(x)
     nx = len(sx)
     xlist = np.array(sorted(list(sx)))
-    dx = np.diff(xlist)
-    assert np.allclose(dx, dx[0])
-    dx = dx[0]
+    if nx == 1:
+        dx = 0
+    elif nx > 1:
+        dx = np.diff(xlist)
+        assert np.allclose(dx, dx[0])
+        dx = dx[0]
+    else:
+        raise ValueError("Length of x vector was < 1!")
+
     return min(x), max(x), dx, nx
 
 
@@ -129,12 +138,20 @@ def read_cst_ascii_3d_field(filePath, n_header=2):
     # print(columns, units)
 
     field_columns = list(
-        set([c[:2] for c in columns if c.startswith("E") or c.startswith("H")])
+        set(
+            [
+                c[:2]
+                for c in columns
+                if c.startswith("E") or c.startswith("H") or c.startswith("B")
+            ]
+        )
     )
 
     if all([f.startswith("E") for f in field_columns]):
         field_type = "electric"
-    elif all([f.startswith("H") for f in field_columns]):
+    elif all([f.startswith("H") for f in field_columns]) or all(
+        [f.startswith("B") for f in field_columns]
+    ):
         field_type = "magnetic"
     else:
         raise ValueError("Mixed CST mode not curretly supported.")