added first and last to docs

Author: Jolanrensen

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

@@ -812,6 +812,14 @@ class Access : TestBase() {
         df.select { drop(2) }
         df.select { dropLast(2) }
 
+        // find the first column satisfying the condition
+        df.select { first { it.name().startsWith("year") } }
+
+        // find the last column inside a column group satisfying the condition
+        df.select {
+            group("name").last { it.name().endsWith("Name") }
+        }
+
         // depth-first-search traversal of all columns, excluding ColumnGroups from result
         df.select { allDfs() }
 

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

@@ -812,6 +812,14 @@ class Access : TestBase() {
         df.select { drop(2) }
         df.select { dropLast(2) }
 
+        // find the first column satisfying the condition
+        df.select { first { it.name().startsWith("year") } }
+
+        // find the last column inside a column group satisfying the condition
+        df.select {
+            group("name").last { it.name().endsWith("Name") }
+        }
+
         // depth-first-search traversal of all columns, excluding ColumnGroups from result
         df.select { allDfs() }
 

docs/StardustDocs/topics/ColumnSelectors.md

@@ -206,6 +206,14 @@ df.select { takeLast(2) }
 df.select { drop(2) }
 df.select { dropLast(2) }
 
+// find the first column satisfying the condition
+df.select { first { it.name().startsWith("year") } }
+
+// find the last column inside a column group satisfying the condition
+df.select {
+    group("name").last { it.name().endsWith("Name") }
+}
+
 // depth-first-search traversal of all columns, excluding ColumnGroups from result
 df.select { allDfs() }