init research

dataframe/docs/StardustDocs/topics/duplicate.md

@@ -0,0 +1,20 @@
+[//]: # (title: duplicate)
+
+Returns [`DataFrame`](DataFrame.md) with original [`DataRow`](DataRow.md) repeated `n` times.
+```text
+DataRow.duplicate(n): DataFrame
+```
+
+Returns [`FrameColumn`](DataColumn.md#framecolumn) with original [`DataFrame`](DataFrame.md) repeated `n` times. 
+Resulting [`FrameColumn`](DataColumn.md#framecolumn) will have an empty [`name`](DataColumn.md#properties).
+
+**Related operations**: [](appendDuplicate.md)
+
+```text
+DataFrame.duplicate(n): FrameColumn
+```
+
+Returns [`DataFrame`](DataFrame.md) where rows that satisfy to the given [condition](DataRow.md#row-conditions) are repeated `n` times. If `rowCondition` is not specified all rows will be duplicated.
+```text
+DataFrame.duplicateRows(n) [ { rowCondition } ]: DataFrame
+```