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Core - Math helpers

This page lists all math operations available in the core package of lo.

• Range

  mathcore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  Creates a slice of integers of the given length starting at 0. Negative length produces a descending sequence.

  lo.Range(4)
  // []int{0, 1, 2, 3}
  
  lo.Range(-4)
  // []int{0, -1, -2, -3}

  Similar:

  rangefromrangewithstepsrepeatrepeatbytimes

  Prototype:

  func Range(elementNum int) []int

• RangeFrom

  mathcore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  Creates a slice starting at start with the specified length. Negative length yields a descending sequence.

  lo.RangeFrom(1, 5)
  // []int{1, 2, 3, 4, 5}

  Similar:

  rangerangewithstepsrepeatrepeatbytimes

  Prototype:

  func RangeFrom[T constraints.Integer | constraints.Float](start T, elementNum int) []T

• RangeWithSteps

  mathcore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  Creates a slice progressing from start up to, but not including, end by step. Returns empty if step is 0 or direction mismatches.

  lo.RangeWithSteps(0, 20, 5)
  // []int{0, 5, 10, 15}

  Similar:

  rangerangefromrepeatrepeatbytimes

  Prototype:

  func RangeWithSteps[T constraints.Integer | constraints.Float](start, end, step T) []T

• Clamp

  mathcore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  Clamps a number within inclusive lower and upper bounds.

  lo.Clamp(42, -10, 10)
  // 10

  Similar:

  maxmaxbymeanminminbyproductsum

  Prototype:

  func Clamp[T constraints.Ordered](value T, mIn T, mAx T) T

• Sum

  mathcore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  Sums the values in a collection. Returns 0 for an empty collection.

  lo.Sum([]int{1, 2, 3, 4, 5})
  // 15

  Similar:

  maxmaxbymeanmeanbyminminbymodeproductproductbysumby

  Prototype:

  func Sum[T constraints.Float | constraints.Integer | constraints.Complex](collection []T) T

• SumBy

  mathcore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  Sums the values computed by a predicate across a collection. Returns 0 for an empty collection.

  strings := []string{"foo", "bar"}
  lo.SumBy(strings, func(item string) int {
      return len(item)
  })
  // 6

  // See also: SumByErr for error handling
  strings := []string{"foo", "bar", "baz"}
  sum, err := lo.SumByErr(strings, func(item string) (int, error) {
      if item == "bar" {
          return 0, fmt.Errorf("invalid item: %s", item)
      }
      return len(item), nil
  })
  // sum: 3, err: invalid item: bar

  Similar:

  meanmeanbyproductproductbysumsumbyerr

  Prototype:

  func SumBy[T any, R constraints.Float | constraints.Integer | constraints.Complex](collection []T, iteratee func(item T) R) R

• SumByErr

  mathcore

  🧩 Source📚 GoDoc

  Sums the values computed by a predicate across a collection, stopping early and returning an error if the predicate returns one. Returns 0 for an empty collection.

  strings := []string{"foo", "bar", "baz"}
  sum, err := lo.SumByErr(strings, func(item string) (int, error) {
      if item == "bar" {
          return 0, fmt.Errorf("invalid item: %s", item)
      }
      return len(item), nil
  })
  // sum: 3, err: invalid item: bar

  strings := []string{"foo", "bar"}
  sum, err := lo.SumByErr(strings, func(item string) (int, error) {
      return len(item), nil
  })
  // sum: 6, err: nil

  strings := []string{}
  sum, err := lo.SumByErr(strings, func(item string) (int, error) {
      return len(item), nil
  })
  // sum: 0, err: nil

  Similar:

  meanbyproductbysumsumby

  Prototype:

  func SumByErr[T any, R constraints.Float | constraints.Integer | constraints.Complex](collection []T, iteratee func(item T) (R, error)) (R, error)

• Product

  mathcore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  Calculates the product of the values in a collection. Returns 1 for nil or empty collections.

  lo.Product([]int{1, 2, 3, 4, 5})
  // 120

  Similar:

  maxmaxbymeanmeanbyminminbymodeproductbysumsumby

  Prototype:

  func Product[T constraints.Float | constraints.Integer | constraints.Complex](collection []T) T

• ProductBy

  mathcore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  Calculates the product of values computed by a predicate. Returns 1 for nil or empty collections.

  strings := []string{"foo", "bar"}
  lo.ProductBy(strings, func(item string) int {
      return len(item)
  })
  // 9

  Similar:

  maxbymaxindexbymeanmeanbyminbyminindexbyproductproductbyerrsumsumby

  Prototype:

  func ProductBy[T any, R constraints.Float | constraints.Integer | constraints.Complex](collection []T, iteratee func(item T) R) R

• ProductByErr

  mathcore

  🧩 Source📚 GoDoc

  Calculates the product of values computed by a predicate. Returns 1 for nil or empty collections.

  If the iteratee returns an error, iteration stops and the error is returned.

  strings := []string{"foo", "bar"}
  result, err := lo.ProductByErr(strings, func(item string) (int, error) {
      return len(item), nil
  })
  // 9, <nil>

  Example with error:

  strings := []string{"foo", "bar", "baz"}
  result, err := lo.ProductByErr(strings, func(item string) (int, error) {
      if item == "bar" {
          return 0, fmt.Errorf("bar is not allowed")
      }
      return len(item), nil
  })
  // 3, error("bar is not allowed")

  Similar:

  maxbymeanbyminbyproductproductbysumbyerr

  Prototype:

  func ProductByErr[T any, R constraints.Float | constraints.Integer | constraints.Complex](collection []T, iteratee func(item T) (R, error)) (R, error)

• Mean

  mathcore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  Calculates the arithmetic mean of a collection of numbers. Returns 0 for an empty collection.

  lo.Mean([]int{2, 3, 4, 5})
  // 3

  Similar:

  maxmaxbymeanbyminminbymodeproductproductbysumsumby

  Prototype:

  func Mean[T constraints.Float | constraints.Integer](collection []T) T

• MeanBy

  mathcore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  Calculates the mean of values computed by a predicate. Returns 0 for an empty collection.

  list := []string{"aa", "bbb", "cccc", "ddddd"}
  lo.MeanBy(list, func(item string) float64 {
      return float64(len(item))
  })
  // 3.5

  Similar:

  maxmaxbymeanmeanbyerrminminbymodeproductproductbysumsumby

  Prototype:

  func MeanBy[T any, R constraints.Float | constraints.Integer](collection []T, iteratee func(item T) R) R

• MeanByErr

  mathcore

  🧩 Source📚 GoDoc

  Calculates the mean of values computed by a predicate. Returns 0 for an empty collection.

  If the iteratee returns an error, iteration stops and the error is returned.

  list := []string{"aa", "bbb", "cccc", "ddddd"}
  result, err := lo.MeanByErr(list, func(item string) (float64, error) {
      return float64(len(item)), nil
  })
  // 3.5, <nil>

  Example with error:

  list := []string{"aa", "bbb", "cccc", "ddddd"}
  result, err := lo.MeanByErr(list, func(item string) (float64, error) {
      if item == "cccc" {
          return 0, fmt.Errorf("cccc is not allowed")
      }
      return float64(len(item)), nil
  })
  // 0, error("cccc is not allowed")

  Similar:

  maxmaxbymeanmeanbyminminbymodeproductproductbysumsumbyerr

  Prototype:

  func MeanByErr[T any, R constraints.Float | constraints.Integer](collection []T, iteratee func(item T) (R, error)) (R, error)

• Mode

  mathcore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  Returns the mode(s), i.e., the most frequent value(s) in a collection. If multiple values share the highest frequency, returns all. Empty input yields an empty slice.

  lo.Mode([]int{2, 2, 3, 3})
  // []int{2, 3}

  Similar:

  countvaluescountvaluesbymaxmaxbymeanmeanbyminminbyproductproductbysumsumby

  Prototype:

  func Mode[T constraints.Integer | constraints.Float](collection []T) []T