added missing source file

src/main/kotlin/kravis/util/DeparseBuilder.kt

@@ -0,0 +1,44 @@
+package kravis.util
+
+import org.jetbrains.kotlinx.dataframe.DataFrame
+import org.jetbrains.kotlinx.dataframe.api.Infer
+import org.jetbrains.kotlinx.dataframe.api.toColumn
+import org.jetbrains.kotlinx.dataframe.api.toDataFrame
+
+// todo javadoc example needed
+/** Create a data-frame from a list of objects */
+fun <T> Iterable<T>.deparseRecords(mapping: (T) -> DataFrameRow) = DataFrame.fromRecords(this, mapping)
+
+internal typealias DeparseFormula<T> = T.(T) -> Any?
+
+inline fun <reified T> Iterable<T>.deparseRecords(vararg mapping: Pair<String, DeparseFormula<T>>): DataFrame<*> {
+    //    val revMapping = mapping.toMap().entries.associateBy({ it.value }) { it.key }
+    val mappings = mapOf<String, Any?>().toMutableMap().apply { putAll(mapping) }
+
+    val function = { record: T ->
+        mapping.toMap().map { (name, deparse) -> name to deparse(record, record) }.toMap() as DataFrameRow
+    }
+    return DataFrame.fromRecords(this, function)
+}
+
+
+infix fun <T> String.with(that: DeparseFormula<T>) = Pair(this, that)
+
+typealias DataFrameRow = Map<String, Any?>
+
+/** Create a data-frame from a list of objects */
+fun <T> DataFrame.Companion.fromRecords(records: Iterable<T>, mapping: (T) -> DataFrameRow): DataFrame<*> {
+    val rowData = records.map { mapping(it) }
+    val columnNames = mapping(records.first()).keys
+
+    val columnData = columnNames.map { it to emptyList<Any?>().toMutableList() }.toMap()
+
+    for(record in rowData) {
+        columnData.forEach { colName, colData -> colData.add(record[colName]) }
+    }
+
+    val map = columnData.map { (name, data) -> data.toColumn("data", Infer.Type) }
+    return map.toDataFrame()
+}
+
+