Fixed and improved the read_resistance function for better resistance…

… handling. Fixes yaqwsx#117

pcbdraw/plot.py

@@ -951,20 +951,20 @@ def _apply_resistor_code(self, root: etree.Element, id_prefix: str, ref: str, va
 
     def _get_resistance_from_value(self, value: str) -> Tuple[Decimal, str]:
         res, tolerance = None, "5%"
+        value_l = value.split(" ", maxsplit=1)
         try:
-            value_l = value.split(" ", maxsplit=1)
             res = read_resistance(value_l[0])
-            if len(value_l) > 1:
-                t_string = value_l[1].strip().replace(" ", "")
-                if "%" in t_string:
-                    s = self._plotter.get_style("tht-resistor-band-colors")
-                    if not isinstance(s, dict):
-                        raise RuntimeError(f"Invalid style specified, tht-resistor-band-colors should be dictionary, got {type(s)}")
-                    if t_string.strip() not in s:
-                        raise UserWarning(f"Invalid resistor tolerance {value_l[1]}")
-                    tolerance = t_string
-        except decimal.InvalidOperation:
-            raise UserWarning(f"Invalid value {value}") from None
+        except ValueError:
+            raise UserWarning(f"Invalid resistor value {value_l[0]}")
+        if len(value_l) > 1:
+            t_string = value_l[1].strip().replace(" ", "")
+            if "%" in t_string:
+                s = self._plotter.get_style("tht-resistor-band-colors")
+                if not isinstance(s, dict):
+                    raise RuntimeError(f"Invalid style specified, tht-resistor-band-colors should be dictionary, got {type(s)}")
+                if t_string.strip() not in s:
+                    raise UserWarning(f"Invalid resistor tolerance {value_l[1]}")
+                tolerance = t_string
         return res, tolerance
 
 

pcbdraw/unit.py

@@ -15,25 +15,35 @@ def erase(string: str, what: List[str]) -> str:
 def read_resistance(value: str) -> Decimal:
     """
     Given a string, try to parse resistance and return it as Ohms (Decimal)
+
+    This function can raise a ValueError if the value is invalid
     """
     p_value = erase(value, ["Ω", "Ohms", "Ohm"]).strip()
     p_value = p_value.replace(" ", "") # Sometimes there are spaces after decimal place
     unit_prefixes = {
-        "m": [Decimal(1e-3), Decimal(1e-6)],
-        "K": [Decimal(1e3), Decimal(1)],
-        "k": [Decimal(1e3), Decimal(1)],
-        "M": [Decimal(1e6), Decimal(1e3)],
-        "G": [Decimal(1e9), Decimal(1e6)]
+        "m": Decimal('1e-3'),
+        "R": Decimal('1'),
+        "K": Decimal('1e3'),
+        "k": Decimal('1e3'),
+        "M": Decimal('1e6'),
+        "G": Decimal('1e9')
     }
     try:
         numerical_value = None
         for prefix, table in unit_prefixes.items():
             if prefix in p_value:
-                split = [Decimal(x) if x != "" else Decimal(0) for x in p_value.split(prefix)]
-                numerical_value = split[0] * table[0] + split[1] * table[1]
+                # Example: 4k7 will have the 4 converted to Decimal(4) and 7 to Decimal(0.7)
+                # Then each gets multiplied by the factor and added, so 4000 + 700
+                # This method ensures that 4k7 and 4k700 for example yields the same result
+                split = p_value.split(prefix)
+                n_whole = Decimal(split[0]) if split[0] != "" else Decimal(0)
+                n_dec = Decimal('.'+split[1]) if split[1] != "" else Decimal(0)
+                numerical_value = n_whole * table + n_dec * table
                 break
-        if numerical_value is not None:
-            return numerical_value
+        if numerical_value is None:
+            # If this fails, a decimal.InvalidOperation is raised which is handled by the Exception catch
+            numerical_value = Decimal(p_value)
+        return numerical_value
     except Exception:
         pass
     raise ValueError(f"Cannot parse '{value}' to resistance")