Add insert.before { }

core/api/core.api

@@ -2609,6 +2609,8 @@ public final class org/jetbrains/kotlinx/dataframe/api/InsertKt {
 	public static final fun after (Lorg/jetbrains/kotlinx/dataframe/api/InsertClause;Lorg/jetbrains/kotlinx/dataframe/columns/ColumnAccessor;)Lorg/jetbrains/kotlinx/dataframe/DataFrame;
 	public static final fun after (Lorg/jetbrains/kotlinx/dataframe/api/InsertClause;Lorg/jetbrains/kotlinx/dataframe/columns/ColumnPath;)Lorg/jetbrains/kotlinx/dataframe/DataFrame;
 	public static final fun at (Lorg/jetbrains/kotlinx/dataframe/api/InsertClause;I)Lorg/jetbrains/kotlinx/dataframe/DataFrame;
+	public static final fun before (Lorg/jetbrains/kotlinx/dataframe/api/InsertClause;Ljava/lang/String;)Lorg/jetbrains/kotlinx/dataframe/DataFrame;
+	public static final fun before (Lorg/jetbrains/kotlinx/dataframe/api/InsertClause;Lkotlin/jvm/functions/Function2;)Lorg/jetbrains/kotlinx/dataframe/DataFrame;
 	public static final fun insert (Lorg/jetbrains/kotlinx/dataframe/DataFrame;Lorg/jetbrains/kotlinx/dataframe/DataColumn;)Lorg/jetbrains/kotlinx/dataframe/api/InsertClause;
 	public static final fun under (Lorg/jetbrains/kotlinx/dataframe/api/InsertClause;Ljava/lang/String;)Lorg/jetbrains/kotlinx/dataframe/DataFrame;
 	public static final fun under (Lorg/jetbrains/kotlinx/dataframe/api/InsertClause;Lkotlin/jvm/functions/Function2;)Lorg/jetbrains/kotlinx/dataframe/DataFrame;

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/insert.kt

@@ -16,6 +16,8 @@ import org.jetbrains.kotlinx.dataframe.documentation.ExcludeFromSources
 import org.jetbrains.kotlinx.dataframe.documentation.Indent
 import org.jetbrains.kotlinx.dataframe.documentation.LineBreak
 import org.jetbrains.kotlinx.dataframe.documentation.SelectingColumns
+import org.jetbrains.kotlinx.dataframe.impl.api.afterImpl
+import org.jetbrains.kotlinx.dataframe.impl.api.beforeImpl
 import org.jetbrains.kotlinx.dataframe.impl.api.insertImpl
 import org.jetbrains.kotlinx.dataframe.impl.columnName
 import org.jetbrains.kotlinx.dataframe.impl.removeAt
@@ -338,10 +340,59 @@ public fun <T> InsertClause<T>.after(columnPath: ColumnPath): DataFrame<T> {
     return df.insertImpl(dstPath, column).move { dstPath }.after { columnPath }
 }
 
-internal fun <T> InsertClause<T>.afterImpl(columnPath: ColumnPath): DataFrame<T> {
-    val dstPath = ColumnPath(columnPath.removeAt(columnPath.size - 1) + column.name())
-    return df.insertImpl(dstPath, column).move { dstPath }.after { columnPath }
-}
+// endregion
+
+// region before
+
+/**
+ * Inserts the new column previously specified with [insert]
+ * at the position immediately before the selected [column] (on the same level).
+ *
+ * For more information: {@include [DocumentationUrls.Insert]}
+ *
+ * See [Grammar][InsertDocs.Grammar] for more details.
+ *
+ * See also: [SelectingColumns.Dsl].
+ *
+ * ### Examples:
+ * ```kotlin
+ * // Insert a new column "age" before the "name" column
+ * df.insert(age).before { name }
+ *
+ * // Insert a new column "sum" before the nested "min" column (inside the "stats" column group)
+ * val dfWithSum = df.insert("sum") { a + b }.before { stats.min }
+ * ```
+ *
+ * @param [column] The [ColumnSelector] used to choose an existing column in this [DataFrame],
+ * before which the new column will be inserted.
+ * @return A new [DataFrame] with the inserted column placed before the selected column.
+ */
+@Refine
+@Interpretable("InsertBefore0")
+public fun <T> InsertClause<T>.before(column: ColumnSelector<T, *>): DataFrame<T> = beforeImpl(df.getColumnPath(column))
+
+/**
+ * Inserts the new column previously specified with [insert]
+ * at the position immediately before the column with the given [name][column].
+ *
+ * For more information: {@include [DocumentationUrls.Insert]}
+ *
+ * See [Grammar][InsertDocs.Grammar] for more details.
+ *
+ * See also: [SelectingColumns.ColumnNames].
+ *
+ * ### Example
+ * ```kotlin
+ * // Insert a new column "age" before the "name" column
+ * df.insert(age).before("name")
+ * ```
+ *
+ * @param [column] The [String] name of the column in this [DataFrame]
+ * before which the new column will be inserted.
+ * @return A new [DataFrame] with the inserted column placed before the specified column.
+ */
+public fun <T> InsertClause<T>.before(column: String): DataFrame<T> =
+    df.add(this.column).move(this.column).before(column)
 
 // endregion
 

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/api/insert.kt

@@ -4,14 +4,19 @@ import org.jetbrains.kotlinx.dataframe.AnyBaseCol
 import org.jetbrains.kotlinx.dataframe.AnyCol
 import org.jetbrains.kotlinx.dataframe.DataColumn
 import org.jetbrains.kotlinx.dataframe.DataFrame
+import org.jetbrains.kotlinx.dataframe.api.InsertClause
+import org.jetbrains.kotlinx.dataframe.api.after
+import org.jetbrains.kotlinx.dataframe.api.before
 import org.jetbrains.kotlinx.dataframe.api.cast
+import org.jetbrains.kotlinx.dataframe.api.move
 import org.jetbrains.kotlinx.dataframe.api.toDataFrame
 import org.jetbrains.kotlinx.dataframe.columns.ColumnGroup
 import org.jetbrains.kotlinx.dataframe.columns.ColumnPath
 import org.jetbrains.kotlinx.dataframe.impl.columns.tree.ReadonlyTreeNode
 import org.jetbrains.kotlinx.dataframe.impl.columns.tree.ReferenceData
 import org.jetbrains.kotlinx.dataframe.impl.columns.tree.getAncestor
 import org.jetbrains.kotlinx.dataframe.impl.columns.withDf
+import org.jetbrains.kotlinx.dataframe.impl.removeAt
 
 internal data class ColumnToInsert(
     val insertionPath: ColumnPath,
@@ -148,3 +153,13 @@ internal fun <T> insertImpl(
 
     return newColumns.toDataFrame().cast()
 }
+
+internal fun <T> InsertClause<T>.afterImpl(columnPath: ColumnPath): DataFrame<T> {
+    val dstPath = ColumnPath(columnPath.removeAt(columnPath.size - 1) + column.name())
+    return df.insertImpl(dstPath, column).move { dstPath }.after { columnPath }
+}
+
+internal fun <T> InsertClause<T>.beforeImpl(columnPath: ColumnPath): DataFrame<T> {
+    val dstPath = ColumnPath(columnPath.removeAt(columnPath.size - 1) + column.name())
+    return df.insertImpl(dstPath, column).move { dstPath }.before { columnPath }
+}

core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/testSets/person/DataFrameTreeTests.kt

@@ -25,6 +25,7 @@ import org.jetbrains.kotlinx.dataframe.api.asDataFrame
 import org.jetbrains.kotlinx.dataframe.api.asFrame
 import org.jetbrains.kotlinx.dataframe.api.asGroupBy
 import org.jetbrains.kotlinx.dataframe.api.at
+import org.jetbrains.kotlinx.dataframe.api.before
 import org.jetbrains.kotlinx.dataframe.api.by
 import org.jetbrains.kotlinx.dataframe.api.cast
 import org.jetbrains.kotlinx.dataframe.api.colsOf
@@ -702,6 +703,22 @@ class DataFrameTreeTests : BaseTest() {
         typed2.insert(colName) { nameAndCity.name.reversed() }.after { nameAndCity.name }.check()
     }
 
+    @Test
+    fun `insert column before`() {
+        val colName = "reversed"
+
+        fun DataFrame<GroupedPerson>.check() {
+            nameAndCity.columnsCount() shouldBe 3
+            nameAndCity.columnNames() shouldBe listOf(
+                typed2.nameAndCity.name.name(),
+                colName,
+                typed2.nameAndCity.city.name(),
+            )
+        }
+
+        typed2.insert(colName) { nameAndCity.name.reversed() }.before { nameAndCity.city }.check()
+    }
+
     @Test
     fun append() {
         val res = typed2.append(listOf("Bill", "San Francisco"), null, 66)