Sankey
Flows between nodes. What the sankey is for, the data it needs and every option it has.
4 min read
On this page
Flows between nodes. It sits in the Flow & network group of the widget library.
When to use it#
A Sankey shows money moving from sources to targets, with each band's width showing the amount. It answers "how does cash flow from my accounts into spending categories?". Each row names a source, a target and, optionally, an amount.
When to pick something else#
- Following items through three or more ordered steps? Use an Alluvial.
- Two-way flows among a few accounts? Use a Chord diagram.
- Only the totals matter? Use a Bar chart.
The data it needs#
Pick these in the Data tab of the inspector. BankSync suggests a column for each when your source has an obvious match.
| Field | Needed | Pick | Notes |
|---|---|---|---|
| Source | Yes | a category | |
| Target | Yes | a category | |
| Value | Yes | a number |
Rows that share a category are combined before drawing: choose Sum, Average, Count, Min or Max on the value field. See Binding data.
Sankey options#
Set these on the Style tab of the inspector. "Automatic" means BankSync picks a value from the chart's size and data.
| Option | What it does | Values | New charts start with |
|---|---|---|---|
| Flow colour | Colour each flow like the node it leaves, the node it reaches, or a gradient between the two. | Source, Target, Gradient | Gradient |
| Node alignment | Which column a node is placed in: pushed left, pushed right, centred, or spread so end nodes sit at the far right. | Left, Right, Center, Justify | Justify |
| Node width | Width of each node bar, in pixels. | Number, 0 or more | Automatic |
| Node gap | Vertical space between nodes in the same column, in pixels. | Number, 0 or more | Automatic |
| Show labels | Write each node’s name beside it. | On or off | Automatic |
| Label size | Text size of the node labels, in pixels (kept between 8 and 16). | Number | Automatic |
| Label colour | Colour of the label text. Leave empty for an automatic, readable colour. | Colour | Automatic |
| Show node totals | Add each node’s total flow after its name. | On or off | Automatic |
| Flow opacity | How solid the flows are, from 0 (clear) to 1 (solid). | Number, 0 to 1 | Automatic |
Needs history#
Show a note instead of the chart until the rows cover enough periods, so a first week never reads as a trend.
| Option | What it does | Values | New charts start with |
|---|---|---|---|
| Date field | The date column whose distinct periods are counted. | Text | Automatic |
| Period | What counts as one period: a day, week, month, quarter or year. | Day, Week, Month, Quarter, Year | Automatic |
| Periods needed | How many distinct periods the rows must cover before the chart draws (2 to 60). | Whole number, 2 to 60 | Automatic |
| Waiting message | Shown until there is enough history. Leave empty for a message naming the periods. | Text, up to 120 characters | Automatic |
Shared chart styling#
Every chart also has the shared styling options. These apply to this one:
- Legend: position, layout and which series show.
- Axes: titles, tick labels and number format.
- Grid, title, padding and background.
- Value labels on the marks.
- Categories and labels: top N with "Other", sort order, readable labels, the handwritten callout.
- Style: corner radius, line width, opacity and animation.
- Tooltip on hover.
- Click to filter: clicking a mark can filter the rest of the dashboard. See Filters and cross-filtering.
- Colours: follow the dashboard palette or pick one for this chart.
Messy data#
- Only positive amounts become flows. Zero and negative amounts are skipped, so if money out is stored as negative, read the value as spending first.
- Rows with a blank source or target, and flows from a node to itself, are skipped. With nothing left you see "No flows to show".
- Repeated source-target pairs are added into one band.
- A loop, like checking to savings and back, is drawn to a copy marked "Flows back to this node".
- Small nodes in a crowded column fold into "Other (n)". About 20 nodes are kept.
On a phone#
A phone card leaves little room between columns, so node labels are dropped when the gap gets too narrow and you tap to read them. Keep it to two columns with a few nodes each, or use a Bar chart of totals on phones.
Related charts#
- Chord diagram: Cross-category links
- Alluvial: Multi-stage flow
- Network graph: Force-directed nodes + edges
- Arc diagram: Linear node arcs
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