Merge pull request #22 from gleam-community/list-at-hotfix

`list.at` hotfix

gleam.toml

@@ -1,5 +1,5 @@
 name = "gleam_community_maths"
-version = "1.1.0"
+version = "1.1.1"
 
 licences = ["Apache-2.0"]
 description = "A basic maths library"
@@ -7,7 +7,7 @@ repository = { type = "github", user = "gleam-community", repo = "maths" }
 gleam = ">= 0.32.0"
 
 [dependencies]
-gleam_stdlib = "~> 0.34"
+gleam_stdlib = "~> 0.38"
 
 [dev-dependencies]
 gleeunit = "~> 1.0"

manifest.toml

@@ -2,10 +2,10 @@
 # You typically do not need to edit this file
 
 packages = [
-  { name = "gleam_stdlib", version = "0.36.0", build_tools = ["gleam"], requirements = [], otp_app = "gleam_stdlib", source = "hex", outer_checksum = "C0D14D807FEC6F8A08A7C9EF8DFDE6AE5C10E40E21325B2B29365965D82EB3D4" },
+  { name = "gleam_stdlib", version = "0.38.0", build_tools = ["gleam"], requirements = [], otp_app = "gleam_stdlib", source = "hex", outer_checksum = "663CF11861179AF415A625307447775C09404E752FF99A24E2057C835319F1BE" },
   { name = "gleeunit", version = "1.1.2", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleeunit", source = "hex", outer_checksum = "72CDC3D3F719478F26C4E2C5FED3E657AC81EC14A47D2D2DEBB8693CA3220C3B" },
 ]
 
 [requirements]
-gleam_stdlib = { version = "~> 0.34" }
+gleam_stdlib = { version = "~> 0.38" }
 gleeunit = { version = "~> 1.0" }

src/gleam_community/maths/metrics.gleam

@@ -20,7 +20,7 @@
 ////<style>
 ////    .katex { font-size: 1.1em; }
 ////</style>
-//// 
+////
 //// ---
 //// 
 //// Metrics: A module offering functions for calculating distances and other 
@@ -46,15 +46,15 @@
 ////   * [`median`](#median)
 ////   * [`variance`](#variance)
 ////   * [`standard_deviation`](#standard_deviation)
-//// 
+////
 
-import gleam_community/maths/elementary
+import gleam/bool
-import gleam_community/maths/piecewise
-import gleam_community/maths/arithmetics
-import gleam_community/maths/predicates
-import gleam_community/maths/conversion
 import gleam/list
 import gleam/pair
+import gleam_community/maths/arithmetics
+import gleam_community/maths/conversion
+import gleam_community/maths/elementary
+import gleam_community/maths/piecewise
 import gleam/set
 import gleam/float
 import gleam/int
@@ -258,7 +258,7 @@ pub fn norm(
 ///
 ///     pub fn example() {
 ///       let assert Ok(tol) = elementary.power(-10.0, -6.0)
-///     
+///
 ///       // Empty lists returns an error
 ///       metrics.manhattan_distance([], [], option.None)
 ///       |> should.be_error()
@@ -329,7 +329,7 @@ pub fn manhattan_distance(
 ///       // Differing lengths returns error
 ///       metrics.minkowski_distance([], [1.0], 1.0, option.None)
 ///       |> should.be_error()
-///     
+///
 ///       // Test order < 1
 ///       metrics.minkowski_distance([0.0, 0.0], [0.0, 0.0], -1.0, option.None)
 ///       |> should.be_error()
@@ -580,7 +580,7 @@ pub fn mean(arr: List(Float)) -> Result(Float, String) {
 ///       [1., 2., 3.]
 ///       |> metrics.median()
 ///       |> should.equal(Ok(2.))
-///     
+///
 ///       [1., 2., 3., 4.]
 ///       |> metrics.median()
 ///       |> should.equal(Ok(2.5))
@@ -593,33 +593,31 @@ pub fn mean(arr: List(Float)) -> Result(Float, String) {
 ///     </a>
 /// </div>
 ///
-pub fn median(arr: List(Float)) -> Result(Float, String) {
+pub fn median(arr: List(Float)) -> Result(Float, Nil) {
-  case arr {
+  use <- bool.guard(list.is_empty(arr), Error(Nil))
-    [] ->
+  let length = list.length(arr)
-      "Invalid input argument: The list is empty."
+  let mid = length / 2
-      |> Error
+
-    _ -> {
+  case length % 2 == 0 {
-      let count: Int = list.length(arr)
+    True -> do_median(arr, mid, True, 0)
-      let mid: Int = list.length(arr) / 2
+    False -> do_median(arr, mid, False, 0)
-      let sorted: List(Float) = list.sort(arr, float.compare)
+  }
-      case predicates.is_odd(count) {
+}
-        // If there is an odd number of elements in the list, then the median
+
-        // is just the middle value
+fn do_median(
-        True -> {
+  xs: List(Float),
-          let assert Ok(val0) = list.at(sorted, mid)
+  mid: Int,
-          val0
+  mean: Bool,
-          |> Ok
+  index: Int,
-        }
+) -> Result(Float, Nil) {
-        // If there is an even number of elements in the list, then the median
+  use <- bool.guard(index > mid, Error(Nil))
-        // is the mean of the two middle values
+  let mid_less_one = mid - 1
-        False -> {
+
-          let assert Ok(val0) = list.at(sorted, mid - 1)
+  case xs {
-          let assert Ok(val1) = list.at(sorted, mid)
+    [x, ..] if !mean && index == mid -> Ok(x)
-          [val0, val1]
+    [x, y, ..] if mean && index == mid_less_one -> Ok({ x +. y } /. 2.0)
-          |> mean()
+    [_, ..rest] -> do_median(rest, mid, mean, index + 1)
-        }
+    [] -> Error(Nil)
-      }
-    }
   }
 }
 
@@ -650,12 +648,12 @@ pub fn median(arr: List(Float)) -> Result(Float, String) {
 ///     pub fn example () {
 ///       // Degrees of freedom
 ///       let ddof: Int = 1
-///     
+///
 ///       // An empty list returns an error
 ///       []
 ///       |> metrics.variance(ddof)
 ///       |> should.be_error()
-///     
+///
 ///       // Valid input returns a result
 ///       [1., 2., 3.]
 ///       |> metrics.variance(ddof)
@@ -727,12 +725,12 @@ pub fn variance(arr: List(Float), ddof: Int) -> Result(Float, String) {
 ///     pub fn example () {
 ///       // Degrees of freedom
 ///       let ddof: Int = 1
-///     
+///
 ///       // An empty list returns an error
 ///       []
 ///       |> metrics.standard_deviationddof)
 ///       |> should.be_error()
-///     
+///
 ///       // Valid input returns a result
 ///       [1., 2., 3.]
 ///       |> metrics.standard_deviation(ddof)
@@ -759,7 +757,7 @@ pub fn standard_deviation(arr: List(Float), ddof: Int) -> Result(Float, String)
         False -> {
           let assert Ok(variance) = variance(arr, ddof)
           // The computed variance will always be positive
-          // So an error should never be returned 
+          // So an error should never be returned
           let assert Ok(stdev) = elementary.square_root(variance)
           stdev
           |> Ok

src/gleam_community/maths/piecewise.gleam

@@ -20,11 +20,11 @@
 ////<style>
 ////    .katex { font-size: 1.1em; }
 ////</style>
-//// 
+////
 //// ---
-//// 
+////
 //// Piecewise: A module containing functions that have different definitions depending on conditions or intervals of their domain.
-//// 
+////
 //// * **Rounding functions**
 ////   * [`ceiling`](#ceiling)
 ////   * [`floor`](#floor)
@@ -52,11 +52,11 @@
 ////   * [`arg_maximum`](#arg_maximum)
 ////
 
-import gleam/option
+import gleam/int
 import gleam/list
+import gleam/option
 import gleam/order
 import gleam/pair
-import gleam/int
 import gleam_community/maths/conversion
 import gleam_community/maths/elementary
 
@@ -66,7 +66,7 @@ import gleam_community/maths/elementary
 ///     </a>
 /// </div>
 ///
-/// The ceiling function rounds a given input value $$x \in \mathbb{R}$$ to the nearest integer value (at the specified digit) that is larger than or equal to the input $$x$$. 
+/// The ceiling function rounds a given input value $$x \in \mathbb{R}$$ to the nearest integer value (at the specified digit) that is larger than or equal to the input $$x$$.
 ///
 /// Note: The ceiling function is used as an alias for the rounding function [`round`](#round) with rounding mode `RoundUp`.
 ///
@@ -325,7 +325,7 @@ pub fn truncate(x: Float, digits: option.Option(Int)) -> Result(Float, String) {
 ///       piecewise.round(12.0654, option.None, option.Some(piecewise.RoundNearest))
 ///       |> should.equal(Ok(12.0))
 ///
-///       // The default rounding mode is "RoundNearest" if None is provided 
+///       // The default rounding mode is "RoundNearest" if None is provided
 ///       piecewise.round(12.0654, option.None, option.None)
 ///       |> should.equal(Ok(12.0))
 ///
@@ -548,7 +548,7 @@ pub fn int_absolute_value(x: Int) -> Int {
 /// The absolute difference:
 ///
 /// \\[
-///  \forall x, y \in \mathbb{R}, \\; |x - y|  \in \mathbb{R}_{+}. 
+///  \forall x, y \in \mathbb{R}, \\; |x - y|  \in \mathbb{R}_{+}.
 /// \\]
 ///
 /// The function takes two inputs $$x$$ and $$y$$ and returns a positive float
@@ -589,7 +589,7 @@ pub fn float_absolute_difference(a: Float, b: Float) -> Float {
 /// The absolute difference:
 ///
 /// \\[
-///  \forall x, y \in \mathbb{Z}, \\; |x - y|  \in \mathbb{Z}_{+}. 
+///  \forall x, y \in \mathbb{Z}, \\; |x - y|  \in \mathbb{Z}_{+}.
 /// \\]
 ///
 /// The function takes two inputs $$x$$ and $$y$$ and returns a positive integer
@@ -628,7 +628,7 @@ pub fn int_absolute_difference(a: Int, b: Int) -> Int {
 /// </div>
 ///
 /// The function takes an input $$x \in \mathbb{R}$$ and returns the sign of
-/// the input, indicating whether it is positive (+1.0), negative (-1.0), or 
+/// the input, indicating whether it is positive (+1.0), negative (-1.0), or
 /// zero (0.0).
 ///
 /// <div style="text-align: right;">
@@ -874,7 +874,7 @@ pub fn maximum(x: a, y: a, compare: fn(a, a) -> order.Order) -> a {
 /// </div>
 ///
 /// The minmax function takes two arguments $$x, y$$ along with a function
-/// for comparing $$x, y$$. The function returns a tuple with the smallest 
+/// for comparing $$x, y$$. The function returns a tuple with the smallest
 /// value first and largest second.
 ///
 /// <details>
@@ -909,7 +909,7 @@ pub fn minmax(x: a, y: a, compare: fn(a, a) -> order.Order) -> #(a, a) {
 ///     </a>
 /// </div>
 ///
-/// Returns the minimum value of a given list. 
+/// Returns the minimum value of a given list.
 ///
 /// <details>
 ///     <summary>Example:</summary>
@@ -923,7 +923,7 @@ pub fn minmax(x: a, y: a, compare: fn(a, a) -> order.Order) -> #(a, a) {
 ///       []
 ///       |> piecewise.list_minimum(int.compare)
 ///       |> should.be_error()
-///     
+///
 ///       // Valid input returns a result
 ///       [4, 4, 3, 2, 1]
 ///       |> piecewise.list_minimum(int.compare)
@@ -944,17 +944,15 @@ pub fn list_minimum(
     [] ->
       "Invalid input argument: The list is empty."
       |> Error
-    _ -> {
+    [x, ..rest] ->
-      let assert Ok(val0) = list.at(arr, 0)
+      Ok(
-      arr
+        list.fold(rest, x, fn(acc: a, element: a) {
-      |> list.fold(val0, fn(acc: a, element: a) {
+          case compare(element, acc) {
-        case compare(element, acc) {
+            order.Lt -> element
-          order.Lt -> element
+            _ -> acc
-          _ -> acc
+          }
-        }
+        }),
-      })
+      )
-      |> Ok
-    }
   }
 }
 
@@ -964,7 +962,7 @@ pub fn list_minimum(
 ///     </a>
 /// </div>
 ///
-/// Returns the maximum value of a given list. 
+/// Returns the maximum value of a given list.
 ///
 /// <details>
 ///     <summary>Example:</summary>
@@ -1000,17 +998,15 @@ pub fn list_maximum(
     [] ->
       "Invalid input argument: The list is empty."
       |> Error
-    _ -> {
+    [x, ..rest] ->
-      let assert Ok(val0) = list.at(arr, 0)
+      Ok(
-      arr
+        list.fold(rest, x, fn(acc: a, element: a) {
-      |> list.fold(val0, fn(acc: a, element: a) {
+          case compare(acc, element) {
-        case compare(acc, element) {
+            order.Lt -> element
-          order.Lt -> element
+            _ -> acc
-          _ -> acc
+          }
-        }
+        }),
-      })
+      )
-      |> Ok
-    }
   }
 }
 
@@ -1026,7 +1022,7 @@ pub fn list_maximum(
 ///     </a>
 /// </div>
 ///
-/// Returns the indices of the minimum values in a given list. 
+/// Returns the indices of the minimum values in a given list.
 ///
 /// <details>
 ///     <summary>Example:</summary>
@@ -1040,7 +1036,7 @@ pub fn list_maximum(
 ///       []
 ///       |> piecewise.arg_minimum(float.compare)
 ///       |> should.be_error()
-///     
+///
 ///       // Valid input returns a result
 ///       [4.0, 4.0, 3.0, 2.0, 1.0]
 ///       |> piecewise.arg_minimum(float.compare)
@@ -1110,7 +1106,7 @@ pub fn arg_minimum(
 ///       []
 ///       |> piecewise.arg_maximum(float.compare)
 ///       |> should.be_error()
-///     
+///
 ///       // Valid input returns a result
 ///       [4.0, 4.0, 3.0, 2.0, 1.0]
 ///       |> piecewise.arg_maximum(float.compare)
@@ -1166,7 +1162,7 @@ pub fn arg_maximum(
 ///     </a>
 /// </div>
 ///
-/// Returns a tuple consisting of the minimum and maximum values of a given list. 
+/// Returns a tuple consisting of the minimum and maximum values of a given list.
 ///
 /// <details>
 ///     <summary>Example:</summary>
@@ -1180,7 +1176,7 @@ pub fn arg_maximum(
 ///       []
 ///       |> piecewise.extrema(float.compare)
 ///       |> should.be_error()
-///     
+///
 ///       // Valid input returns a result
 ///       [4.0, 4.0, 3.0, 2.0, 1.0]
 ///       |> piecewise.extrema(float.compare)
@@ -1202,21 +1198,18 @@ pub fn extrema(
     [] ->
       "Invalid input argument: The list is empty."
       |> Error
-    _ -> {
+    [x, ..rest] ->
-      let assert Ok(val_max) = list.at(arr, 0)
+      Ok(
-      let assert Ok(val_min) = list.at(arr, 0)
+        list.fold(rest, #(x, x), fn(acc: #(a, a), element: a) {
-      arr
+          let first: a = pair.first(acc)
-      |> list.fold(#(val_min, val_max), fn(acc: #(a, a), element: a) {
+          let second: a = pair.second(acc)
-        let first: a = pair.first(acc)
+          case compare(element, first), compare(second, element) {
-        let second: a = pair.second(acc)
+            order.Lt, order.Lt -> #(element, element)
-        case compare(element, first), compare(second, element) {
+            order.Lt, _ -> #(element, second)
-          order.Lt, order.Lt -> #(element, element)
+            _, order.Lt -> #(first, element)
-          order.Lt, _ -> #(element, second)
+            _, _ -> #(first, second)
-          _, order.Lt -> #(first, element)
+          }
-          _, _ -> #(first, second)
+        }),
-        }
+      )
-      })
-      |> Ok
-    }
   }
 }