CODEWITHSUNDEEP
swiftdictionaryreduceflatmap
xceph
xceph

Reputation: 1046

Swift - Reducing a Dictionary of Arrays to a single array of same type using map/reduce/flatmap

Given an input like so:

let m = ["one": ["1","2","3"],
         "two":["4","5"]
    ]

how can I use map/reduce to produce the output like:

["1","2","3","4","5"]

I'm not very swifty, and trying to learn it but I cant seem to figure out an efficient way to do this simple operation. My verbose approach would be like so:

var d = [String]()

for (key, value) in m {
    value.forEach { (s) in
        d.append(s)
    }
}
print(d)

I'm sure this can be a 1 liner, could someone assist?

Upvotes: 0

Views: 860

Answers (1)

Alexander
Alexander

Reputation: 63271

All you need is a single flatMap:

let result = dict.flatMap { _, values in values }

Upvotes: 2

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