wip

Author: Jolanrensen

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

@@ -51,6 +51,18 @@ public interface ColumnSelectionDsl<out T> : ColumnsContainer<T> {
 
     public operator fun <C> ColumnPath.invoke(): DataColumn<C> = getColumn(this).cast()
 
+    public operator fun <T> KProperty<T>.invoke(): DataColumn<T> = this@ColumnSelectionDsl[this]
+
+    public operator fun <T> KProperty<DataRow<T>>.invoke(): ColumnGroup<T> = this@ColumnSelectionDsl[this]
+
+    public operator fun <T> KProperty<DataFrame<T>>.invoke(): FrameColumn<T> = this@ColumnSelectionDsl[this]
+
+    public operator fun <T, R> KProperty<DataRow<T>>.get(column: KProperty<R>): DataColumn<R> = invoke()[column]
+
+    public operator fun <T, R> KProperty<DataRow<T>>.get(column: KProperty<DataRow<R>>): ColumnGroup<R> = invoke()[column]
+
+    public operator fun <T, R> KProperty<DataRow<T>>.get(column: KProperty<DataFrame<R>>): FrameColumn<R> = invoke()[column]
+
     public operator fun <C> String.invoke(): DataColumn<C> = getColumn(this).cast()
 
     public operator fun String.get(column: String): ColumnPath = pathOf(this, column)

core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/samples/api/Access.kt

@@ -706,6 +706,39 @@ class Access : TestBase() {
         // SampleEnd
     }
 
+    @Test
+    fun columnSelectors_kProperties() {
+        // SampleStart
+        df.select { it[Person::name] }
+        df.select { (Person::name)() }
+
+        // by column path
+        df.select { it[Person::name][Name::firstName] }
+        df.select { Person::name[Name::firstName] }
+
+        // with a new name
+        df.select { Person::name named "Full Name" }
+
+        // converted
+        df.select { Person::name[Name::firstName].map { it.lowercase() } }
+
+        // column arithmetics
+        df.select { 2021 - Person::age }
+
+        // two columns
+        df.select { Person::name and Person::age }
+
+        // range of columns
+        df.select { Person::name..Person::age }
+
+        // all children of ColumnGroup
+        df.select { Person::name.all() }
+
+        // dfs traversal of all children columns
+        df.select { Person::name.allDfs() }
+        // SampleEnd
+    }
+
     @Test
     fun columnSelectors_strings() {
         // SampleStart