Recipe steps that change the number of rows in the dataset have additional impacts on your dataset and its samples. These reshaping steps include the following transformations:

TransformationDocumentation
SplitrowsInitial Parsing Steps
Expand Arrays into Rows 
Filter Rows (keep or delete)Filter Data
Pivot TablePivot Data
Unpivot Columns 
Join DatasetsJoin Panel
Union DatasetsUnion Page
Select Lookup from the column menuLookup Wizard
Remove Duplicate RowsFilter Data

Samples:

When one of these transformations is applied and rows are removed from your dataset:

For more information, see Samples Panel.