---
title: "min(by:)"
framework: swift
role: symbol
role_heading: Instance Method
path: "swift/joinedsequence/min(by:)"
---

# min(by:)

Returns the minimum element in the sequence, using the given predicate as the comparison between elements.

## Declaration

```swift
@warn_unqualified_access func min(by areInIncreasingOrder: (Self.Element, Self.Element) throws -> Bool) rethrows -> Self.Element?
```

## Parameters

- `areInIncreasingOrder`: A predicate that returns true if its first argument should be ordered before its second argument; otherwise, false.

## Return Value

Return Value The sequence’s minimum element, according to areInIncreasingOrder. If the sequence has no elements, returns nil.

## Discussion

Discussion The predicate must be a strict weak ordering over the elements. That is, for any elements a, b, and c, the following conditions must hold: areInIncreasingOrder(a, a) is always false. (Irreflexivity) If areInIncreasingOrder(a, b) and areInIncreasingOrder(b, c) are both true, then areInIncreasingOrder(a, c) is also true. (Transitive comparability) Two elements are incomparable if neither is ordered before the other according to the predicate. If a and b are incomparable, and b and c are incomparable, then a and c are also incomparable. (Transitive incomparability) This example shows how to use the min(by:) method on a dictionary to find the key-value pair with the lowest value. let hues = ["Heliotrope": 296, "Coral": 16, "Aquamarine": 156] let leastHue = hues.min { a, b in a.value < b.value } print(leastHue) // Prints "Optional((key: "Coral", value: 16))" note: O(n), where n is the length of the sequence.