CODEWITHSUNDEEP
arraysswift
ShevO27
ShevO27

Reputation: 916

How to find minimal non zero INT in an array in swift 5.0?

I have some array, and I need to find minimal non zero integer in each row. Is there a way of doing it with min(by:)?

for example

var row = [0,0,0,0,0,0,0,0,1,3,5,6,9]

so I need to get 1

by doing row.min() I always get 0.

I was told that I can do it with min{by:} but I don't fully understand the syntax.

Upvotes: 4

Views: 1387

Answers (4)

Alexander
Alexander

Reputation: 63321

Just filter your array to keep all elements greater than 0, and find the min among those.

Use a lazy operation to prevent the intermediate array allocation usually caused by Array.filter(_:). See https://stackoverflow.com/a/51917427/1630618 for more details.

let minNonZeroValue = row.lazy.filter { 0 < $0 }.min()

Upvotes: 6

AamirR
AamirR

Reputation: 12208

You can filter the array for desired values, and use Array.min() method, like so

row.filter{ $0 > 0 }.min()

Or following will only work if array has ordered numbers

row.first(where: { $0 > 0 })

Upvotes: 8

Arkku
Arkku

Reputation: 42149

There are obviously many ways, one way (which doesn't create an intermediate array, or require row to be sorted) is with reduce:

row.reduce(nil as Int?) { minSoFar, this in
    guard this != 0 else { return minSoFar }
    guard let minSoFar = minSoFar else { return this }
    return min(minSoFar, this)
}

Which is equivalent to, but more readable than, the shorter:

row.reduce(nil as Int?) { $1 != 0 ? min($0 ?? $1, $1) : $0 }

The result is optional, since there might not be any non-zero elements.

edit: The min(by:) solution could also indeed be used, but it is also somewhat unreadable and returns 0 in case there are no non-zero elements (instead of nil):

row.min { $0 == 0 ? false : ($1 == 0 ? true : $0 < $1) }

Upvotes: 2

Ahmad F
Ahmad F

Reputation: 31655

You could do it like this:

let result = row.lazy.filter { $0 > 0 }.min()

Note that result is an optional Int since result might not contain any element that matches the condition.

Upvotes: 3

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