resistor_equivalence.py

# https://byjus.com/equivalent-resistance-formula/

from __future__ importannotations


defresistor_parallel(resistors: list[float]) ->float:
"""
 Req = 1/ (1/R1 + 1/R2 + ... + 1/Rn)

 >>> resistor_parallel([3.21389, 2, 3])
 0.8737571620498019
 >>> resistor_parallel([3.21389, 2, -3])
 Traceback (most recent call last):
 ...
 ValueError: Resistor at index 2 has a negative or zero value!
 >>> resistor_parallel([3.21389, 2, 0.000])
 Traceback (most recent call last):
 ...
 ValueError: Resistor at index 2 has a negative or zero value!
 """

first_sum=0.00
forindex, resistorinenumerate(resistors):
ifresistor<=0:
msg=f"Resistor at index {index} has a negative or zero value!"
raiseValueError(msg)
first_sum+=1/float(resistor)
return1/first_sum


defresistor_series(resistors: list[float]) ->float:
"""
 Req = R1 + R2 + ... + Rn

 Calculate the equivalent resistance for any number of resistors in parallel.

 >>> resistor_series([3.21389, 2, 3])
 8.21389
 >>> resistor_series([3.21389, 2, -3])
 Traceback (most recent call last):
 ...
 ValueError: Resistor at index 2 has a negative value!
 """
sum_r=0.00
forindex, resistorinenumerate(resistors):
sum_r+=resistor
ifresistor<0:
msg=f"Resistor at index {index} has a negative value!"
raiseValueError(msg)
returnsum_r


if__name__=="__main__":
importdoctest

doctest.testmod()