Create and use an alluvial diagram

Alluvial diagrams are a style of Sankey diagram that show the relationship, or flow, between groups of categorical values, such as periods of time. The flow between categories indicates the magnitude of a relationship but does not indicate a direction. However, directional flow may be inferred based on the context of the categories on the diagram.

Alluvial diagrams can answer questions about the data, such as What is the volume of flow between categories?

Example

A GIS analyst is analyzing fruit and vegetable imports into the United States. An alluvial diagram can be used to analyze the flow of products (in millions of dollars) into the United States by country of origin and type of product.

Data from the USDA, Economic Research Service summary of data released by U.S. Department of Commerce, Census Bureau. Downloaded January, 2018.

Create an alluvial diagram

To create an alluvial diagram, complete the following steps:

1. Select one of the following combinations of data:
   • Two or more string fields
   • Two or more string fields and a number or rate/ratio field

   Note:

   If you do not select a number or rate/ratio field, the data will be aggregated and a count will be displayed.

   You can search for fields using the search bar in the data pane.

2. Create the alluvial diagram by doing the following:
   1. Drag the selected fields to a new card.
   2. Hover over the Chart drop zone.
   3. Drop the selected fields on Alluvial Diagram.

Tip:

You can also create charts using the Chart menu above the data pane or the Visualization type button on an existing card. For the Chart menu, only charts that are compatible with the data selection will be enabled. For the Visualization type menu, only compatible visualizations (including maps, charts, or tables) will be displayed.

Usage notes

Alluvial diagrams are styled by unique values.

The fields used to create the alluvial diagram are arranged as vertical columns (dimensions) with each value from the field appearing as a node. The nodes are connected by flows that show the relationship between the two categories. The thickness of each flow is determined by its value.

The flows in the alluvial diagram can be symbolized as a count of features in the categories or as a number or rate/ratio field. If a field is used, the values can be calculated as a sum, minimum, maximum, average, percentile, or median of values from the field.

Note:

Median and percentile are not available for certain remote feature layers. If the remote feature layer does not support median or percentile, you can copy the layer to your workbook.

Use the Layer options button to open the Layer options pane. Use the Legend tab to view the symbols and make selections on the chart. To change the color associated with a value, click the symbol and choose a color from the palette or provide a hexadecimal value. The pop-out legend button displays the legend as a separate card on the page.

Use the Card filter button to remove any unwanted data from the card. Filters can be applied to all string, number, rate/ratio, and date/time fields. A card filter does not affect other cards using the same dataset.

Use the Selection tools button to select features on the chart using the single select tool, or invert the selection.

Use the Zoom tools button to zoom in or out on the chart.

Use the Visualization type button to switch directly between an alluvial diagram and other visualizations, such as a grouped summary table, bar chart with a subgroup field, data clock, or chord diagram.

Use the Maximize button to enlarge the card. Other cards on the page will be reduced to thumbnails. The card can be returned to its previous size using the Restore down button .

Note:

Alluvial charts maintain their aspect ratio when the card is resized. Therefore, the chart may not fill the entire card when resized.

Use the Enable cross filters button to allow filters to be created on the card using selections on other cards. Cross filters can be removed using the Disable cross filters button .

Use the Flip card button to view the back of the card. The Card info tab provides information about the data on the card and the Export data tab allows users to export the data from the card.

Use the Card options button to access the following options:

• Appearance button —Change the background color, foreground color, and border of the card.
• Edit labels button —Create custom labels for the chart axes. To edit the labels, click the Edit labels button and click the axis to make it editable.
• Order button —Move the card forward or move the card backward relative to other cards on the page.
• Delete button —Remove the card from the page. If you did not intend to delete the card, you can retrieve it using the Undo button .

How alluvial diagrams work

An alluvial diagram consists of the following components:

Label	Component	Description
	Dimension	Dimensions are a group of categorical values (nodes), such as a period of time or classification. Each dimension represents a field used to create the diagram.
	Flow	Flows show the relationship between nodes in different dimensions. The thickness of each flow is determined by its value.
	Node	Nodes represent the categorical values that are grouped together to create a dimension. Each node represents a unique value within a field used to create the diagram.

Resources

Use the following resources to learn more about charts:

• Create a chart
• Chart layer options
• Chart toolbar