utils + parallel resistors calculator

.gitignore

@@ -1 +1,2 @@
 .notes.txt
+__pycache__/

parallel_resistors.py

@@ -0,0 +1,18 @@
+#!/bin/python
+from utils import parse_resistors
+
+def get_input():
+    raw_input_resistors = input("Enter resistor values separated by spaces or commas: ")
+    resistors = parse_resistors(raw_input_resistors)
+    return resistors
+
+def calculate_resistance(resistors):
+    return 1 / sum(1 / r for r in resistors)
+
+if __name__ == '__main__':
+    try:
+        resistors = get_input()
+    except ValueError as e:
+        print(e)
+        exit(1)
+    print(f"Total resistance = {calculate_resistance(resistors)} ohms")

utils.py

@@ -0,0 +1,27 @@
+#!/bin/python
+import re
+
+def parse_resistors(raw_input):
+    values = []
+    tokens = raw_input.replace(',', ' ').split()
+
+    for token in tokens:
+        match = re.fullmatch(r'([0-9]*\.?[0-9]+)\s*([KM]?)', token)
+        if not match:
+            raise ValueError(f"Invalid component value '{token}'")
+
+        number = float(match.group(1))
+        if number <= 0:
+            raise ValueError(f"Invalid component value '{token}' (must be positive)")
+
+        suffix = match.group(2)
+        if suffix == 'K':
+            multiplier = 1e3
+        elif suffix == 'M':
+            multiplier = 1e6
+        else:
+            multiplier = 1.0
+
+        values.append(number * multiplier)
+
+    return values

voltage_divider.py

@@ -1,5 +1,5 @@
 #!/bin/python
-import re
+from utils import parse_resistors
 
 def find_bests(desired_ratio, resistors):
     # only keep the 5 best candidates
@@ -22,31 +22,6 @@ def find_bests(desired_ratio, resistors):
     for i, (error, R1, R2, ratio) in enumerate(candidates, start=1):
         print(f"{i}. R1 = {R1} Ω, R2 = {R2} Ω  -> ratio = {ratio:.6f}, error = {error:.6e}")
 
-def parse_resistors(raw_input):
-    values = []
-    tokens = raw_input.replace(',', ' ').split()
-
-    for token in tokens:
-        match = re.fullmatch(r'([0-9]*\.?[0-9]+)\s*([KM]?)', token)
-        if not match:
-            raise ValueError(f"Invalid component value '{token}'")
-
-        number = float(match.group(1))
-        if number <= 0:
-            raise ValueError(f"Invalid component value '{token}' (must be positive)")
-
-        suffix = match.group(2)
-        if suffix == 'K':
-            multiplier = 1e3
-        elif suffix == 'M':
-            multiplier = 1e6
-        else:
-            multiplier = 1.0
-
-        values.append(number * multiplier)
-
-    return values
-
 def get_ratio():
     while True:
         try: