Add convenience function to get column from a grid

Author: jsoberg

README.md

@@ -10,7 +10,7 @@ This can be added to a [Kotlin Advent of Code template repository](https://githu
 
 ```kts
 dependencies {
-    implementation("com.github.jsoberg:Kotlin-AoC-Utilities:2025.2")
+    implementation("com.github.jsoberg:Kotlin-AoC-Utilities:2025.3")
 }
 ```
 

buildSrc/src/main/kotlin/Publishing.kt

@@ -1,5 +1,5 @@
 object Publishing {
     const val ArtifactId = "Kotlin-AoC-Utilities"
     const val GroupId = "com.github.jsoberg"
-    const val Version = "2025.2"
+    const val Version = "2025.3"
 }

src/main/kotlin/com/soberg/aoc/utlities/datastructures/Grid2D.kt

@@ -29,6 +29,17 @@ data class Grid2D<T>(
 
     infix operator fun contains(location: Location): Boolean = isInBounds(location)
 
+    /** @return The column element values for column at index [col], or an error if [col] is not a valid index for this grid. */
+    fun column(col: Int): List<T> {
+        if (!isInBounds(row = 0, col = col)) {
+            error("Column at index $col does not exist")
+        }
+
+        return (0 until rowSize).map { row ->
+            get(row = row, col = col)
+        }
+    }
+
     /** @return true if the specified [location] is in the bounds of this grid, false if not. */
     fun isInBounds(location: Location): Boolean = isInBounds(location.row, location.col)
 

src/test/kotlin/com/soberg/aoc/utlities/datastructures/Grid2DTest.kt

@@ -50,6 +50,20 @@ class Grid2DTest {
             .isEqualTo(4444)
     }
 
+    @Test
+    fun `return expected elements for column`() {
+        val actual = testGrid.column(2)
+        assertThat(actual)
+            .containsExactly(3, 33, 333, 3333, 33333)
+    }
+
+    @Test
+    fun `throw error when column doesn't exist`() {
+        assertThrows<IllegalStateException> {
+            testGrid.column(100)
+        }
+    }
+
     @Test
     fun `return expected element for elementAt`() {
         val actual = testGrid.elementAt(Location(2, 2), Direction.NorthWest, 2)