Calculate of prices in within an array of strings Array

Question

I have an array that describes a list of auto parts (Swift/IOS,array already in such structure arrived from other source.):

let parts = [
    "Wheel = 230$",
    "Door = 200$",
    "Wheel = 300$",
    "Seat = 150$",
    "Seat = 150$",
    "Rugs = 100$"]

I need to calculate the sum of the prices of the auto parts for each type of part. Here's the result I'm looking for:

let expectedResult = [
    "wheel 530$",
    "Door 200$",
    "Seat 300$",
    "Rugs 100$"
]

I don’t understand how to do it.

Checksum? Btw you have fancy quotes in your second code block, you should replace with `"`. — aheze, Aug 04 '21 at 20:31
This *code* doesn’t even compile. And what does checksum mean? — vadian, Aug 04 '21 at 20:32
Could you add more details? What kind of checksum are you looking for, exactly? — Alexander, Aug 04 '21 at 20:34
Use a custom type instead of strings that must be parsed. Looks like OP wants to sum the amounts for each item, for instance there are two “Seat” so the sum is 300 for that item — Joakim Danielson, Aug 04 '21 at 20:36
Also: don't use the leading comma style in Swift. It was invented in SQL as a workaround for its terrbile syntax, and the way it explodes when having excess commas. Swift ignores an excess trailing comma, so it doesn't have that issue, thus no need for that gross workaround. — Alexander, Aug 04 '21 at 20:36
@AlekseiResnianskii Ohhh, that has nothing to do with "checksums". — Alexander, Aug 04 '21 at 21:02
This question still needs a lot of formatting and grammar improvements, but I think it's at least *answerable* now. Please omit statements like "I ask for help from knowledgeable people.", they're not relevant. I've voted to reopen it — Alexander, Aug 04 '21 at 21:07

score 0 · Accepted Answer · answered Aug 05 '21 at 06:48

Here is a solution where I loop through the array and split each element on "=" and then sum the values together using a dictionary. Once that is done the dictionary is converted back to an array

let parts = [
    "Wheel = 230$",
    "Door = 200$",
    "Wheel = 300$",
    "Seat = 150$",
    "Seat = 150$",
    "Rugs = 100$"]

var values = [String: Int]() // Used to calculate totals per part

parts.forEach { string in
    let split = string.split(separator: "=")

    // Make sure the split worked as expected and that we have an integer value after the =
    guard split.count == 2,
          let value = Int(String(split[1]).trimmingCharacters(in: .whitespaces).dropLast()) else { return }

    let key = String(split[0]).trimmingCharacters(in: .whitespaces)

    // Sum values over the part name
    values[key, default: 0] += value
}

// Convert back to an array of strings
let output = values.map { "\($0.key) \($0.value)$"}

print(output)

Thank you so much! This is a very elegant solution. – Asbjorn Rasen Aug 05 '21 at 09:32 — Asbjorn Rasen, Aug 05 '21 at 09:32

Calculate of prices in within an array of strings Array

1 Answers1