Sankey diagram is a variation of flow diagram, in which the width of the  connectors (links) is proportional to the quantity of flow between two connected items (nodes).

In Partek Flow Sankey plots are used to visualize different classes of nucleotide variants (single nucleotide variants or SNVs, as well as indels) and filter variants based on those classes. Sankey plot is automatically created for each Annotated Variants data node and depicts the classification of variants for the selected sample (one at the time) with respect to the particular annotation model (Figure 1).

Plot controls are on the left. The first one is the Variant file drop-down list, which is used to display another sample within the same project. The Selected annotations panel shows the annotations that are visible on the plot (as data nodes); to remove one from the plot, select the red minus icon on the right. To add an annotation use the - Add annotation - drop-down list. The sequence of the annotations / nodes from left to right can be changed using the Selected annotation panel, by dragging and dropping the annotation classes. Figure 2 shows the same plot as in Figure 1, after moving the Region class  to the left.

The plot is interactive and acts as a filter tool. Selecting one of the variant classes on the plot (left-click, Control & left-click to select multiple) and then pushing the Apply selection as filter turns on the filter and applies it to the table of variants below the plot. To turn off the filter, click outside the plot. The filter shown in Figure 3 keeps only SNVs in the variant table (i.e. filters out the indels).