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Sankey

Overview

The sankey trace type is used to create Sankey diagrams, which visualize the flow of quantities between different nodes (or categories). Sankey diagrams are commonly used to show the transfer of resources or values, with the width of the flow lines being proportional to the size of the flow.

You can customize the colors, labels, and flow paths to represent your data and flows effectively.

Common Uses

  • Flow of Resources: Visualizing how resources (e.g., money, energy, or materials) move between stages.
  • Part-to-Part Relationships: Displaying how parts contribute to other parts rather than the whole.
  • Energy or Supply Chains: Showing energy transfers or supply chain processes.

Check out the Attributes for the full set of configuration options

Examples

Common Configurations

Here's a simple sankey diagram showing how values flow between different categories:

You can copy this code below to create this chart in your project:

models:
  - name: sankey-data
    args:
      - echo
      - |
        source,target,value
        A,B,10
        A,C,5
        B,D,15
        C,D,5
traces:
  - name: Simple Sankey Diagram
    model: ref(sankey-data)
    props:
      type: sankey
      node:
        label: query(unique([source, target]))
      link:
        source: query(source)
        target: query(target)
        value: query(value)
charts:
  - name: Simple Sankey Diagram
    traces:
      - ref(Simple Sankey Diagram)
    layout:
      title:
        text: Simple Sankey Diagram<br><sub>Flow of Resources Between Nodes</sub>

This example demonstrates a sankey diagram with custom node and link colors:

Here's the code:

models:
  - name: sankey-data-colors
    args:
      - echo
      - |
        source,target,value,color
        X,Y,10,#1f77b4
        X,Z,5,#ff7f0e
        Y,W,15,#2ca02c
        Z,W,5,#d62728
traces:
  - name: Sankey Diagram with Custom Colors
    model: ref(sankey-data-colors)
    props:
      type: sankey
      node:
        label: query(unique([source, target]))
        color: query(color)
      link:
        source: query(source)
        target: query(target)
        value: query(value)
charts:
  - name: Sankey Diagram with Custom Colors
    traces:
      - ref(Sankey Diagram with Custom Colors)
    layout:
      title:
        text: Sankey Diagram with Custom Colors<br><sub>Custom Colors for Nodes and Links</sub>

This example shows a sankey diagram where hover information displays both the value and the source-target relationship:

Here's the code:

models:
  - name: sankey-data-hover
    args:
      - echo
      - |
        source,target,value
        P,Q,20
        P,R,10
        Q,S,15
        R,S,5
traces:
  - name: Sankey Diagram with Hover Information
    model: ref(sankey-data-hover)
    props:
      type: sankey
      node:
        label: query(unique([source, target]))
      link:
        source: query(source)
        target: query(target)
        value: query(value)
        hoverinfo: "source+target+value"
charts:
  - name: Sankey Diagram with Hover Information
    traces:
      - ref(Sankey Diagram with Hover Information)
    layout:
      title:
        text: Sankey Diagram with Hover Information<br><sub>Hover Info Displaying Value and Relationships</sub>

Attributes

These attributes apply to traces where trace.props.type is set to sankey. You would configure these attributes on the trace with the trace.props object. 

arrangement: 'enumerated , one of ( "snap" | "perpendicular" | "freeform" | "fixed"
  )' #(1)!
customdata: 'data array' #(2)!
domain:
  column: 'integer greater than or equal to 0' #(3)!
  row: 'integer greater than or equal to 0' #(4)!
  x: 'array' #(5)!
  y: 'array' #(6)!
hoverinfo: 'flaglist string. any combination of joined with a "+" or "all" or "none"
  or "skip".' #(7)!
hoverlabel:
  align: 'enumerated or array of enumerateds , one of ( "left" | "right" | "auto"
    )' #(8)!
  bgcolor: 'color or array of colors' #(9)!
  bordercolor: 'color or array of colors' #(10)!
  font:
    color: color or array of colors
    family: 'string or array of strings' #(11)!
    size: number or array of numbers greater than or equal to 1
  namelength: 'integer or array of integers greater than or equal to -1' #(12)!
ids: 'data array' #(13)!
legendgrouptitle:
  font:
    color: color
    family: 'string' #(14)!
    size: number greater than or equal to 1
  text: 'string' #(15)!
legendrank: 'number' #(16)!
legendwidth: 'number greater than or equal to 0' #(17)!
link:
  arrowlen: 'number greater than or equal to 0' #(18)!
  color: 'color or array of colors' #(19)!
  colorscales:
    cmax: 'number' #(20)!
    cmin: 'number' #(21)!
    colorscale: 'colorscale' #(22)!
    label: 'string' #(23)!
    name: 'string' #(24)!
    templateitemname: 'string' #(25)!
  customdata: 'data array' #(26)!
  hoverinfo: 'enumerated , one of ( "all" | "none" | "skip" )' #(27)!
  hoverlabel:
    align: 'enumerated or array of enumerateds , one of ( "left" | "right" | "auto"
      )' #(28)!
    bgcolor: 'color or array of colors' #(29)!
    bordercolor: 'color or array of colors' #(30)!
    font:
      color: color or array of colors
      family: 'string or array of strings' #(31)!
      size: number or array of numbers greater than or equal to 1
    namelength: 'integer or array of integers greater than or equal to -1' #(32)!
  hovertemplate: 'string or array of strings' #(33)!
  label: 'data array' #(34)!
  line:
    color: 'color or array of colors' #(35)!
    width: 'number or array of numbers greater than or equal to 0' #(36)!
  source: 'data array' #(37)!
  target: 'data array' #(38)!
  value: 'data array' #(39)!
meta: 'number or categorical coordinate string' #(40)!
node:
  color: 'color or array of colors' #(41)!
  customdata: 'data array' #(42)!
  groups: 'array' #(43)!
  hoverinfo: 'enumerated , one of ( "all" | "none" | "skip" )' #(44)!
  hoverlabel:
    align: 'enumerated or array of enumerateds , one of ( "left" | "right" | "auto"
      )' #(45)!
    bgcolor: 'color or array of colors' #(46)!
    bordercolor: 'color or array of colors' #(47)!
    font:
      color: color or array of colors
      family: 'string or array of strings' #(48)!
      size: number or array of numbers greater than or equal to 1
    namelength: 'integer or array of integers greater than or equal to -1' #(49)!
  hovertemplate: 'string or array of strings' #(50)!
  label: 'data array' #(51)!
  line:
    color: 'color or array of colors' #(52)!
    width: 'number or array of numbers greater than or equal to 0' #(53)!
  pad: 'number greater than or equal to 0' #(54)!
  thickness: 'number greater than or equal to 1' #(55)!
  x: 'data array' #(56)!
  y: 'data array' #(57)!
orientation: 'enumerated , one of ( "v" | "h" )' #(58)!
selectedpoints: 'number or categorical coordinate string' #(59)!
textfont:
  color: color
  family: 'string' #(60)!
  size: number greater than or equal to 1
type: sankey
uirevision: 'number or categorical coordinate string' #(61)!
valueformat: 'string' #(62)!
valuesuffix: 'string' #(63)!
visible: 'enumerated , one of ( true | false | "legendonly" )' #(64)!
  1. If value is snap (the default), the node arrangement is assisted by automatic snapping of elements to preserve space between nodes specified via nodepad. If value is perpendicular, the nodes can only move along a line perpendicular to the flow. If value is freeform, the nodes can freely move on the plane. If value is fixed, the nodes are stationary.
  2. Assigns extra data each datum. This may be useful when listening to hover, click and selection events. Note that, "scatter" traces also appends customdata items in the markers DOM elements
  3. If there is a layout grid, use the domain for this column in the grid for this sankey trace .
  4. If there is a layout grid, use the domain for this row in the grid for this sankey trace .
  5. Sets the horizontal domain of this sankey trace (in plot fraction).
  6. Sets the vertical domain of this sankey trace (in plot fraction).
  7. Determines which trace information appear on hover. If none or skip are set, no information is displayed upon hovering. But, if none is set, click and hover events are still fired. Note that this attribute is superseded by node.hoverinfo and node.hoverinfo for nodes and links respectively.
  8. Sets the horizontal alignment of the text content within hover label box. Has an effect only if the hover label text spans more two or more lines
  9. Sets the background color of the hover labels for this trace
  10. Sets the border color of the hover labels for this trace.
  11. HTML font family - the typeface that will be applied by the web browser. The web browser will only be able to apply a font if it is available on the system which it operates. Provide multiple font families, separated by commas, to indicate the preference in which to apply fonts if they aren't available on the system. The Chart Studio Cloud (at https://chart-studio.plotly.com or on-premise) generates images on a server, where only a select number of fonts are installed and supported. These include "Arial", "Balto", "Courier New", "Droid Sans",, "Droid Serif", "Droid Sans Mono", "Gravitas One", "Old Standard TT", "Open Sans", "Overpass", "PT Sans Narrow", "Raleway", "Times New Roman".
  12. Sets the default length (in number of characters) of the trace name in the hover labels for all traces. -1 shows the whole name regardless of length. 0-3 shows the first 0-3 characters, and an integer >3 will show the whole name if it is less than that many characters, but if it is longer, will truncate to namelength - 3 characters and add an ellipsis.
  13. Assigns id labels to each datum. These ids for object constancy of data points during animation. Should be an array of strings, not numbers or any other type.
  14. HTML font family - the typeface that will be applied by the web browser. The web browser will only be able to apply a font if it is available on the system which it operates. Provide multiple font families, separated by commas, to indicate the preference in which to apply fonts if they aren't available on the system. The Chart Studio Cloud (at https://chart-studio.plotly.com or on-premise) generates images on a server, where only a select number of fonts are installed and supported. These include "Arial", "Balto", "Courier New", "Droid Sans",, "Droid Serif", "Droid Sans Mono", "Gravitas One", "Old Standard TT", "Open Sans", "Overpass", "PT Sans Narrow", "Raleway", "Times New Roman".
  15. Sets the title of the legend group.
  16. Sets the legend rank for this trace. Items and groups with smaller ranks are presented on top/left side while with "reversed"legend.traceorder` they are on bottom/right side. The default legendrank is 1000, so that you can use ranks less than 1000 to place certain items before all unranked items, and ranks greater than 1000 to go after all unranked items.
  17. Sets the width (in px or fraction) of the legend for this trace.
  18. Sets the length (in px) of the links arrow, if 0 no arrow will be drawn.
  19. Sets the link color. It can be a single value, or an array for specifying color for each link. If link.color is omitted, then by default, a translucent grey link will be used.
  20. Sets the upper bound of the color domain.
  21. Sets the lower bound of the color domain.
  22. Sets the colorscale. The colorscale must be an array containing arrays mapping a normalized value to an rgb, rgba, hex, hsl, hsv, or named color string. At minimum, a mapping for the lowest (0) and highest (1) values are required. For example, [[0, 'rgb(0,0,255)'], [1, 'rgb(255,0,0)']]. To control the bounds of the colorscale in color space, use cmin and cmax. Alternatively, colorscale may be a palette name string of the following list: Blackbody,Bluered,Blues,Cividis,Earth,Electric,Greens,Greys,Hot,Jet,Picnic,Portland,Rainbow,RdBu,Reds,Viridis,YlGnBu,YlOrRd.
  23. The label of the links to color based on their concentration within a flow.
  24. When used in a template, named items are created in the output figure in addition to any items the figure already has in this array. You can modify these items in the output figure by making your own item with templateitemname matching this name alongside your modifications (including visible: false or enabled: false to hide it). Has no effect outside of a template.
  25. Used to refer to a named item in this array in the template. Named items from the template will be created even without a matching item in the input figure, but you can modify one by making an item with templateitemname matching its name, alongside your modifications (including visible: false or enabled: false to hide it). If there is no template or no matching item, this item will be hidden unless you explicitly show it with visible: true.
  26. Assigns extra data to each link.
  27. Determines which trace information appear when hovering links. If none or skip are set, no information is displayed upon hovering. But, if none is set, click and hover events are still fired.
  28. Sets the horizontal alignment of the text content within hover label box. Has an effect only if the hover label text spans more two or more lines
  29. Sets the background color of the hover labels for this trace
  30. Sets the border color of the hover labels for this trace.
  31. HTML font family - the typeface that will be applied by the web browser. The web browser will only be able to apply a font if it is available on the system which it operates. Provide multiple font families, separated by commas, to indicate the preference in which to apply fonts if they aren't available on the system. The Chart Studio Cloud (at https://chart-studio.plotly.com or on-premise) generates images on a server, where only a select number of fonts are installed and supported. These include "Arial", "Balto", "Courier New", "Droid Sans",, "Droid Serif", "Droid Sans Mono", "Gravitas One", "Old Standard TT", "Open Sans", "Overpass", "PT Sans Narrow", "Raleway", "Times New Roman".
  32. Sets the default length (in number of characters) of the trace name in the hover labels for all traces. -1 shows the whole name regardless of length. 0-3 shows the first 0-3 characters, and an integer >3 will show the whole name if it is less than that many characters, but if it is longer, will truncate to namelength - 3 characters and add an ellipsis.
  33. Template string used for rendering the information that appear on hover box. Note that this will override hoverinfo. Variables are inserted using %{variable}, for example "y: %{y}" as well as %{xother}, {%xother}, {%_xother}, {%xother_}. When showing info for several points, "xother" will be added to those with different x positions from the first point. An underscore before or after "(x|y)other" will add a space on that side, only when this field is shown. Numbers are formatted using d3-format's syntax %{variable:d3-format}, for example "Price: %{y:$.2f}". https://github.com/d3/d3-format/tree/v1.4.5#d3-format for details on the formatting syntax. Dates are formatted using d3-time-format's syntax %{variable|d3-time-format}, for example "Day: %{2019-01-01|%A}". https://github.com/d3/d3-time-format/tree/v2.2.3#locale_format for details on the date formatting syntax. The variables available in hovertemplate are the ones emitted as event data described at this link https://plotly.com/javascript/plotlyjs-events/#event-data. Additionally, every attributes that can be specified per-point (the ones that are arrayOk: true) are available. variables value and label. Anything contained in tag <extra> is displayed in the secondary box, for example "{fullData.name}". To hide the secondary box completely, use an empty tag <extra></extra>.
  34. The shown name of the link.
  35. Sets the color of the line around each link.
  36. Sets the width (in px) of the line around each link.
  37. An integer number [0..nodes.length - 1] that represents the source node.
  38. An integer number [0..nodes.length - 1] that represents the target node.
  39. A numeric value representing the flow volume value.
  40. Assigns extra meta information associated with this trace that can be used in various text attributes. Attributes such as trace name, graph, axis and colorbar title.text, annotation text rangeselector, updatemenues and sliders label text all support meta. To access the trace meta values in an attribute in the same trace, simply use %{meta[i]} where i is the index or key of the meta item in question. To access trace meta in layout attributes, use %{data[n[.meta[i]} where i is the index or key of the meta and n is the trace index.
  41. Sets the node color. It can be a single value, or an array for specifying color for each node. If node.color is omitted, then the default Plotly color palette will be cycled through to have a variety of colors. These defaults are not fully opaque, to allow some visibility of what is beneath the node.
  42. Assigns extra data to each node.
  43. Groups of nodes. Each group is defined by an array with the indices of the nodes it contains. Multiple groups can be specified.
  44. Determines which trace information appear when hovering nodes. If none or skip are set, no information is displayed upon hovering. But, if none is set, click and hover events are still fired.
  45. Sets the horizontal alignment of the text content within hover label box. Has an effect only if the hover label text spans more two or more lines
  46. Sets the background color of the hover labels for this trace
  47. Sets the border color of the hover labels for this trace.
  48. HTML font family - the typeface that will be applied by the web browser. The web browser will only be able to apply a font if it is available on the system which it operates. Provide multiple font families, separated by commas, to indicate the preference in which to apply fonts if they aren't available on the system. The Chart Studio Cloud (at https://chart-studio.plotly.com or on-premise) generates images on a server, where only a select number of fonts are installed and supported. These include "Arial", "Balto", "Courier New", "Droid Sans",, "Droid Serif", "Droid Sans Mono", "Gravitas One", "Old Standard TT", "Open Sans", "Overpass", "PT Sans Narrow", "Raleway", "Times New Roman".
  49. Sets the default length (in number of characters) of the trace name in the hover labels for all traces. -1 shows the whole name regardless of length. 0-3 shows the first 0-3 characters, and an integer >3 will show the whole name if it is less than that many characters, but if it is longer, will truncate to namelength - 3 characters and add an ellipsis.
  50. Template string used for rendering the information that appear on hover box. Note that this will override hoverinfo. Variables are inserted using %{variable}, for example "y: %{y}" as well as %{xother}, {%xother}, {%_xother}, {%xother_}. When showing info for several points, "xother" will be added to those with different x positions from the first point. An underscore before or after "(x|y)other" will add a space on that side, only when this field is shown. Numbers are formatted using d3-format's syntax %{variable:d3-format}, for example "Price: %{y:$.2f}". https://github.com/d3/d3-format/tree/v1.4.5#d3-format for details on the formatting syntax. Dates are formatted using d3-time-format's syntax %{variable|d3-time-format}, for example "Day: %{2019-01-01|%A}". https://github.com/d3/d3-time-format/tree/v2.2.3#locale_format for details on the date formatting syntax. The variables available in hovertemplate are the ones emitted as event data described at this link https://plotly.com/javascript/plotlyjs-events/#event-data. Additionally, every attributes that can be specified per-point (the ones that are arrayOk: true) are available. variables value and label. Anything contained in tag <extra> is displayed in the secondary box, for example "{fullData.name}". To hide the secondary box completely, use an empty tag <extra></extra>.
  51. The shown name of the node.
  52. Sets the color of the line around each node.
  53. Sets the width (in px) of the line around each node.
  54. Sets the padding (in px) between the nodes.
  55. Sets the thickness (in px) of the nodes.
  56. The normalized horizontal position of the node.
  57. The normalized vertical position of the node.
  58. Sets the orientation of the Sankey diagram.
  59. Array containing integer indices of selected points. Has an effect only for traces that support selections. Note that an empty array means an empty selection where the unselected are turned on for all points, whereas, any other non-array values means no selection all where the selected and unselected styles have no effect.
  60. HTML font family - the typeface that will be applied by the web browser. The web browser will only be able to apply a font if it is available on the system which it operates. Provide multiple font families, separated by commas, to indicate the preference in which to apply fonts if they aren't available on the system. The Chart Studio Cloud (at https://chart-studio.plotly.com or on-premise) generates images on a server, where only a select number of fonts are installed and supported. These include "Arial", "Balto", "Courier New", "Droid Sans",, "Droid Serif", "Droid Sans Mono", "Gravitas One", "Old Standard TT", "Open Sans", "Overpass", "PT Sans Narrow", "Raleway", "Times New Roman".
  61. Controls persistence of some user-driven changes to the trace: constraintrange in parcoords traces, as well as some editable: true modifications such as name and colorbar.title. Defaults to layout.uirevision. Note that other user-driven trace attribute changes are controlled by layout attributes: trace.visible is controlled by layout.legend.uirevision, selectedpoints is controlled by layout.selectionrevision, and colorbar.(x|y) (accessible with config: {editable: true}) is controlled by layout.editrevision. Trace changes are tracked by uid, which only falls back on trace index if no uid is provided. So if your app can add/remove traces before the end of the data array, such that the same trace has a different index, you can still preserve user-driven changes if you give each trace a uid that stays with it as it moves.
  62. Sets the value formatting rule using d3 formatting mini-languages which are very similar to those in Python. For numbers, see: https://github.com/d3/d3-format/tree/v1.4.5#d3-format.
  63. Adds a unit to follow the value in the hover tooltip. Add a space if a separation is necessary from the value.
  64. Determines whether or not this trace is visible. If "legendonly", the trace is not drawn, but can appear as a legend item (provided that the legend itself is visible).