Sankey diagram

Sankey visualisation

Updated 2 years ago by Template retirement home

How to use this template

Sankey diagram

A template for creating simple two-stage Sankey diagrams. Ideal for displaying the flow of seats between parties from before to after an election.

Data requirements

The template works with two types of data format:

  1. Flows are already in the data, and each row has a source name, target name and flow value.

  2. Flows are not already in the data. In this model, each row is a entity (e.g. a seat in an election), with a source name and target name (e.g. representing the ruling party before and after the election). With this kind of data the flows are computed automatically by adding up each source–target pair.

Tips

  • If specifying flow values directly, the column must contain positive numbers or zero
  • Names are compared and values summed using case-insensitive comparisons with all non-alphanumeric characters stripped. For example “Cat“ and “cA ?t“ are considered identical.
  • Hovering over a link will defocus all other links and any node not connected to that link. Hovering over a node will defocus all links that are not directly connected to that node and all nodes not connected via a link to the hovered node. You can fix focus on a node or link and all its connections by clicking on the entity. This is particularly useful for guiding viewers through your stories. Click a focused node or link again to remove the focus or click any other node or link to change focus to that entity.

This section documents API usage specific to this template, so for an introduction we suggest you refer to the generic API documentation instead.

template: _636

version: _3

Template data

There are two different formats in which you can supply data to this template. Which one will be more convenient for you likely depends on the source of your data, as described below.

Array of objects with arbitrary keys, and a bindings object

This format is most likely useful when you have data from an external source, such as CSV data loaded from d3-dsv. You should supply this attached to the opts.data, which might look like:

    {
        links: [
            { "LinksHeader1": ..., "LinksHeader2": ..., ... },
            { "LinksHeader1": ..., "LinksHeader2": ..., ... },
            { "LinksHeader1": ..., "LinksHeader2": ..., ... },
            ...
        ]
    }

... but with the keys being the column headers from your source data instead. To tell the API how these values from each column should be associated with the keys that the template is expecting, you must also supply an object attached to opts.bindings. (The meanings of the keys in the bindings object are documented below.) The minimal bindings you can supply for this template are as shown in this example:

{
    template: "_636",
    version: "_3",
    bindings: {
        links: {
            source: "LinksHeader1",
            target: "LinksHeader2"
        }
    },
    data: {
        links: [
            { "LinksHeader1": ..., "LinksHeader2": ..., ... },
            { "LinksHeader1": ..., "LinksHeader2": ..., ... },
            { "LinksHeader1": ..., "LinksHeader2": ..., ... },
            ...
        ]
    }
}

All possible bindings that you can supply are shown in this example:

{
    template: "_636",
    version: "_3",
    bindings: {
        links: {
            source: "LinksHeader1",
            target: "LinksHeader2",
            value: "LinksHeader3",
            step_from: "LinksHeader4",
            step_to: "LinksHeader5"
        }
    },
    data: {
        links: [
            { "LinksHeader1": ..., "LinksHeader2": ..., ... },
            { "LinksHeader1": ..., "LinksHeader2": ..., ... },
            { "LinksHeader1": ..., "LinksHeader2": ..., ... },
            ...
        ]
    }
}

(As before, the keys containing "Header" would be replaced by column names from your data source.)

Array of objects with template-defined keys

There is an alternative format you can use, which is likely to be easier to use if your data is not from a spreadsheet source. With this alternative format you supply your data to the template as an array of objects, attached to opts.data, where the keys must be those used by the template, as documented below. In this case there is no need to supply a bindings object, since the key names are already those expected by the template. The required properties in the data object are as follows (scroll down for a description of what each property is):

{
template: "_636",
version: "_3",
data: {
    links: [
        {
            source: ...,
            target: ...
        },
        ...
    ]
},
...
}

And the full list of all possible properties is as follows:

{
template: "_636",
version: "_3",
data: {
    links: [
        {
            source: ...,
            target: ...,
            value: ...,
            step_from: ...,
            step_to: ...
        },
        ...
    ]
},
...
}

Meanings of the template data keys:

  • links.source: source
  • links.target: target
  • links.value: A numerical value used to set the thickness of the links.
  • links.step_from: An integer value used to indicate where a link starts from (used only in Alluvial mode).
  • links.step_to: An integer value used to indicate where a link goes to (used only in Alluvial mode).

Template settings

Options for opts.state.

Layout

mode string

Mode.

Allowed values:

  • alluvial (Alluvial (stepwise composition))
  • sankey (Sankey (arbitrary flows))

iterations number

Iterations.

Max: 100

spread string

Spread.

Allowed values:

  • step (Based on step values)
  • column (Evenly)

alignment string

Allignment.

Allowed values:

  • justify (Justify)
  • center (Centre)
  • left (Left)
  • right (Right)

node_width number

Node width.

Min: 2

Max: 50

node_padding number

Vertical node separation.

Max: 20

margin number

Margin. Maximum margin, may be less on small screens

Max: 50

bg_color color

Background colour.

header.title string

Title.

header.subtitle string

Subtitle.

header.color color

Color.

header.align string

Alignment.

Allowed values:

  • left (fa-align-left)
  • center (fa-align-center)
  • right (fa-align-right)

header.margin number

Margin.

header.margin_advanced boolean

Advanced margin settings.

header.margin_top number

Top.

header.margin_right number

Right.

header.margin_bottom number

Bottom.

header.margin_left number

Left.

color_mode string

Palette type.

Allowed values:

  • single (Single colour)
  • generated (Auto-generated from base colour)
  • palette (Specified palette)

palette colors

Palette.

base_color color

Base colour.

hue_rotation_angle number

Advanced: hue rotation angle. Angle between one colour and the next (HCL colourspace). The default value, equal to 360/(Golden ratio), ensures adjacent colurs are very different and colours are not repeated.

Max: 360

custom_palette text

Custom overrides. Associate nodes with colours using the format <name>:<colour>, one entry per line.

Link opacity.

Max: 1

background_opacity number

Defocused opacity. When a node or link is in focus, this sets the opacity of the others

Max: 1

Labels

label_mode string

Allowed values:

  • outwards (Favour outside)
  • inwards (Favour inside)

label_show_values boolean

Include values in labels.

label_color_mode string

Text.

Allowed values:

  • none (None)
  • auto (Auto)
  • fixed (Fixed)

label_color color

 .

label_outline_color_mode string

Outline.

Allowed values:

  • none (None)
  • auto (Auto)
  • fixed (Fixed)

label_outline_color color

 .

label_responsive boolean

Sizing. Auto changed the label size based on the window size, subject to the specified min and max

Allowed values:

  • true (Auto)
  • false (Fixed)

label_font_size number

In pixels.

label_font_size_min number

Min.

label_font_size_max number

Max.

label_bold boolean

Bold.

When to show.

Allowed values:

  • always (Always)
  • focused (When focused)

Colour.

Number formatting

localization.input_decimal_separator string

Decimal separator in data sheet. Used for interpreting your data. Only change if data is not displaying on the chart as expected.

Allowed values:

  • . (.)
  • , (,)

localization.output_separators string

Number format to display. How the numbers should appear on chart labels

Allowed values:

  • ,. (12,235.67)
  • ., (12.345,67)
  • . (12235.67)
  • , (12345,67)
  • . (12 235.67)
  • , (12 345,67)

formatting.transform_labels boolean

Transform labels.

formatting.transform string

Allowed values:

  • multiply (Multiply by)
  • divide (Divide by)
  • exponentiate (×10 to the power of)

formatting.multiply_divide_constant number

formatting.exponentiate_constant number

formatting.prefix string

Prefix. Text to place in front of labels

formatting.n_dec number

Decimal places. Use negative integers to round to positive powers of ten (eg -2 rounds to the nearest 100)

Min: -10

Max: 10

formatting.suffix string

Suffix. Text to place after labels

formatting.strip_zeros boolean

Strip trailing zeros.

formatting.strip_separator boolean

Strip thousands separator between 1000 and 9999.

footer.source_name string

Source name.

footer.source_url string

Source url.

footer.multiple_sources boolean

Multiple sources.

footer.source_name_2 string

Source name.

footer.source_url_2 string

Source url.

footer.source_name_3 string

Source name.

footer.source_url_3 string

Source url.

footer.source_label string

Source label.

footer.note string

Note.

footer.size number

Size.

footer.color color

Color.

footer.align string

Alignment.

Allowed values:

  • left (fa-align-left)
  • center (fa-align-center)
  • right (fa-align-right)

footer.margin number

Overall.

footer.margin_top number

Top.

footer.margin_right number

Right.

footer.margin_bottom number

Bottom.

footer.margin_left number

Left.

footer.margin_advanced boolean

Advanced.