From 9729fe6dcbc6bece1322d5a60e2784ac57085d26 Mon Sep 17 00:00:00 2001
From: omicron <omicron.me@protonmail.com>
Date: Wed, 21 May 2025 23:04:00 +0200
Subject: [PATCH] Add matrix.CreateFromSlice function

---
 matrix/matrix.go      | 27 +++++++++++++++++++++++++++
 matrix/matrix_test.go | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/matrix/matrix.go b/matrix/matrix.go
index 90d02e0..5dd59bd 100644
--- a/matrix/matrix.go
+++ b/matrix/matrix.go
@@ -54,6 +54,33 @@ func Create[T Number](rows, cols int) *Matrix[T] {
 	}
 }
 
+// Creates a new matrix from a given 2D slice of values. The first index of the
+// slice denotes the rows and the second index denotes the columns. Returns the
+// newly created matrix.
+//
+// Panics with ErrIncompatibleDataDimensions if any of the lengths are 0 or if
+// not all rows have the same length.
+func CreateFromSlice[T Number](values [][]T) *Matrix[T] {
+	rows := len(values)
+	if rows == 0 {
+		panic(ErrInvalidDimensions)
+	}
+	cols := len(values[0])
+	if cols == 0 {
+		panic(ErrInvalidDimensions)
+	}
+
+	m := Create[T](rows, cols)
+	for i := range rows {
+		if len(values[i]) != cols {
+			panic(ErrIncompatibleDataDimensions)
+		}
+		copy(m.values[i], values[i])
+	}
+
+	return m
+}
+
 // Creates a new matrix of a given size and sets the values from the given
 // slice. The values are used to fill the matrix left to right and top to
 // bottom. Returns the newly created matrix.
diff --git a/matrix/matrix_test.go b/matrix/matrix_test.go
index 4b06d6c..22782da 100644
--- a/matrix/matrix_test.go
+++ b/matrix/matrix_test.go
@@ -55,6 +55,41 @@ func TestCreate(t *testing.T) {
 	})
 }
 
+func TestCreateFromSlice(t *testing.T) {
+	m := matrix.CreateFromSlice([][]int{
+		{1, 2, 3},
+		{4, 5, 6},
+	})
+	assert.NotNil(t, m)
+
+	assert.Equal(t, 2, m.Rows())
+	assert.Equal(t, 3, m.Cols())
+
+	assert.Equal(t, 1, m.Get(0, 0))
+	assert.Equal(t, 2, m.Get(0, 1))
+	assert.Equal(t, 3, m.Get(0, 2))
+	assert.Equal(t, 4, m.Get(1, 0))
+	assert.Equal(t, 5, m.Get(1, 1))
+	assert.Equal(t, 6, m.Get(1, 2))
+
+	assert.PanicsWithValue(t, matrix.ErrInvalidDimensions, func() {
+		matrix.CreateFromSlice([][]int{})
+	})
+
+	assert.PanicsWithValue(t, matrix.ErrInvalidDimensions, func() {
+		matrix.CreateFromSlice([][]int{
+			{},
+		})
+	})
+
+	assert.PanicsWithValue(t, matrix.ErrIncompatibleDataDimensions, func() {
+		matrix.CreateFromSlice([][]int{
+			{1, 2, 3},
+			{4, 5},
+		})
+	})
+}
+
 func TestCreateFromFlatSlice(t *testing.T) {
 	m := matrix.CreateFromFlatSlice(2, 3, []int{1, 2, 3, 4, 5, 6})
 	assert.NotNil(t, m)