An implementation of Uber's "Fare Estimator" [CodeSignal]

Question

CodeSignal put out a challenge by Uber that involves writing a "fare estimator" that involves a function dependent on cost per minute, cost per mile, ride time and ride distance.

The formula is along the lines of:

fare = (cost per minute) * (ride time) + (cost per mile) * (ride distance)

where ride time and ride distance are constant integers (or floats) and cost per minute and cost per mile are lists of integers and floats (as cost per minute and cost per mile depend on the car type).

This is my solution:

def fareEstimator(ride_time, ride_distance, cost_per_minute, cost_per_mile):
 y, f = [], lambda w, x, y, z: (w * x) + (y * z)
 for a, b in zip(cost_per_minute, cost_per_mile):
 y.append(f(a, ride_time, b, ride_distance))
 return y

I'm just looking for any kind of feedback on the code. Is there a better way to implement it? Can you recommend better coding styles? Is my algorithm good or is it a steaming pile of wank? Leave any feedback you want!

You can check out the full challenge here (but you might need to sign up): https://app.codesignal.com/company-challenges/uber/HNQwGHfKAoYsz9KX6

• Toby Speight: Can you show how you expect the function to be called? In particular, it helps to know what types the arguments will be.
• Aleksey: It's just called by an external code judge (I didn't implement a main function).
• Toby Speight: Ah, sorry, I see you have described the types of the arguments in the paragraph above the code.

Answer 1

Here are a few tips:

• Unless it makes the code easier to read, avoid multiple assignments in one line. making your code shorter does not necessarily make it better, faster nor more maintainable.

• Give better names to your variables

• Use type hints

So, your code could be changed to this:

from typing import Iterable
def fareEstimator(ride_time: float, ride_distance: float, cost_per_minute_list: Iterable[float],
 cost_per_mile_list: Iterable[float]) -> Iterable[float]:
 result = []
 def calculateFare(ride_time: float, ride_distance: float, cost_per_minute: float,
 cost_per_mile: float) -> float:
 return ride_time*cost_per_minute + ride_distance*cost_per_mile
 for cost_per_minute, cost_per_mile in zip(cost_per_minute_list, cost_per_mile_list):
 result.append(calculateFare(ride_time, ride_distance, cost_per_minute, cost_per_mile))
 return result