Is there a way to declare an arbitrary number of arrays in Swift?

Question

I'm new to programming and to Swift; apologies if I'm asking an obvious question. I'm trying to simulate a ranked-choice voting algorithm. Several parts of it work, but I'm stuck on a basic idea: I need to generate an arbitrary number of arrays that contain each voter's imaginary votes. I want software to produce many arrays that look more or less like this:

var ballot1 = ["candidateB", "candidateA", "candidateD"]
var ballot2 = ["candidateC", "candidateD"]

To this point, I have hand-written the ones I need, but I want to automate the process. Is there a way, in Swift, that I can declare an arbitrary number of those variables-containing-arrays without hand-writing each one? I'd like to be able to specify an arbitrary integer - 10, say...or 2,500? - and let a function spit out that many arrays. (I've separately developed a function to create one array of random-within-parameters length containing random-within-parameters contents, but I'm stuck trying to replicate that function across many arrays.)

I've tried various kinds of for—in loops, but I run into various errors whenever I try to use code to declare the new variable. Is there a simple way to get software to declare variables with names that increment (e.g., ballot1, ballot2, ballot3, etc.)? Am I missing something obvious? Thanks for any advice.

For the first part of your question, it looks like you're looking for multi-dimensional arrays -- for example (https://stackoverflow.com/questions/25127700/two-dimensional-array-in-swift/25127801). Then, for the second part, it looks like you're maybe asking about "names" of the variables because you expect you'll need to access the arrays you create by name. But, in a multidimensional array, you'll access them by index. Like `ballot[0][1]` could give you the second item on the first ballot, for example. — jnpdx, May 24 '21 at 21:03
Or a dictionary with arrays as values and keys as variable names — Joakim Danielson, May 24 '21 at 21:11
Thank you, jnpdx, Joakim Danielson, and Duncan C for your helpful responses! I had originally tried to use a multi-dimensional array of strings to solve this problem, but ran into implementation difficulties I didn't know how to solve. I had changed my approach to the variable-based idea I posed in my question, which allowed me to do the second half of the project (i.e., vote tabulation and statistics) well, but not the first half. With your comments in mind, I went back to the drawing board, used a multidimensional array based on integers, and solved my problem. Thank you! — geoff7, May 27 '21 at 13:43

score 1 · Accepted Answer · answered May 24 '21 at 21:15

Use an array of arrays, as jnpdx says in their comment.

let ballot1 = ["candidateB", "candidateA", "candidateD"] 
let ballot2 = ["candidateC", "candidateD"]
let ballots = [ballot1, ballot2]

or just

let ballots = [["candidateB", "candidateA", "candidateD"],
    ["candidateC", "candidateD"]]

Then you can refer to your ballots using indexes:

ballots[0] would give you an array of candidates for the first ballot, or you could loop through the outer array:

for (index, ballot) in ballots.enumerated() {
   print("Ballot \(index+1) has candidates \(ballot[index])")
}

Note that you might want to make each ballot a struct, with fields for a title, the array of candidates, and any other information you might want. Then you could have an array of ballot structs:

struct Ballot {
   let title: String
   let description: String? // Optional field
   let candidates: [String]
}

And then:

let ballots = [Ballot(title: "5th congressional district",
                  description: nil,
                  candidates: ["Joe", "Briana", "Jamal", "Ivan"]),
               Ballot(title: "Mayor",
                  description: nil,
                  candidates: ["Adrienne", "Moisha", "Dave", "Demtri"])
              ]

And:

for aBallot in ballots {
    print("Ballot titled \(aBallot.title) has candidates \(aBallot.candidates)")

As noted in my above comment, your suggestions were supremely helpful. Thank you for your time and expertise! — geoff7, May 27 '21 at 13:44

Is there a way to declare an arbitrary number of arrays in Swift?

1 Answers1