How to use this template
Sankey diagram
A template for creating Sankey diagrams and alluvial diagrams. Ideal for displaying energy flows or the changes in seats between parties from before to after an election.
Data requirements
The template works with two types of data format:
Flows are already in the data, and each row has a source name, target name and flow value (plus optional step from and step to columns for multistep alluvial diagrams).
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 source–target pairs (taking into account step from and step to values).
Tips
- If specifying flow values directly, the column used for Value of link 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.
- The optional Step from and Step to column selection boxes make it possible to construct multistep alluvial diagrams where links go from Step from to Step to along the horizontal direction. If only Step from is assigned to a column then the value of Step to is assumed to be one greater than that of Step from. Similarly, if only Step to is assigned to a column then the value of Step from is assumed to be one less than that of Step to.
API information
This section documents API usage specific to this template, so for an introduction we suggest you refer to the generic API documentation instead.
template: @flourish/sankey
version: 2
Template data
There are three different formats in which you can supply data to this template. The most convenient for you to use likely depends on the source of your data, as described below.
1. Array of arrays, and a bindings object
You can supply arrays of arrays to opts.data, which might look
like:
{
data: {
links: [
[ "LinksColumn1Value1", "LinksColumn2Value1",
[ "LinksColumn1Value2", "LinksColumn2Value2",
[ "LinksColumn1Value3", "LinksColumn2Value3",
...
]
}
}
where each array of arrays represents the rows in a data sheet.
To tell the API how the 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: "@flourish/sankey",
version: "2",
bindings: {
links: {
source: 0, // index of a column in your data
target: 1, // index of a column in your data
}
},
data: {
links: [
[ "LinksColumn1Value1", "LinksColumn2Value1",
[ "LinksColumn1Value2", "LinksColumn2Value2",
[ "LinksColumn1Value3", "LinksColumn2Value3",
...
]
}
}
All possible bindings that you can supply are shown in this example:
{
template: "@flourish/sankey",
version: "2",
bindings: {
links: {
source: 0, // index of a column in your data
target: 1, // index of a column in your data
value: 2, // index of a column in your data
step_from: 3, // index of a column in your data
step_to: 4, // index of a column in your data
}
},
data: {
links: [
[ "LinksColumn1Value1", "LinksColumn2Value1",
[ "LinksColumn1Value2", "LinksColumn2Value2",
[ "LinksColumn1Value3", "LinksColumn2Value3",
...
]
}
}
2. 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. You must also supply an object attached to
opts.bindings. The minimal bindings you can
supply for this template are as shown in this example:
{
template: "@flourish/sankey",
version: "2",
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: "@flourish/sankey",
version: "2",
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.)
3. 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: "@flourish/sankey",
version: "2",
data: {
links: [
{
source: ...,
target: ...
},
...
]
},
...
}
And the full list of all possible properties is as follows:
{
template: "@flourish/sankey",
version: "2",
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:
iterations number
Iter.. Number of iterations of the layout algorithm before the diagram is drawn. The higher the value, the fewer link crossings you will see but the less likely the order is to match that in the datasheet. Max: 100
spread string
Spread. Allowed values:
alignment string
Alignment. Allowed values:
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.
max_width number
Maximum width. Leave blank to stretch to container width
Node and link appearance
colors.palette colors
Palette.
colors.extend boolean
Auto-extend. Automatically generate additional colours when needed to avoid the palette colours being used more than once. Added colours are based on the average lightness and chroma values of the palette. This works best if the palette’s colours do not have very high or low saturation.
colors.advanced boolean
Fine tune. Fine tune how additional colours are added to the palette.
colors.hue_rotation_angle number
Hue rotation for added colours. Angle, in degrees in HCL colourspace, between one generated colour and the next. The default value, ~360/(Golden ratio), ensures adjacent hues are not too similar. Max: 360
colors.custom_palette text
Custom overrides. Type the name of the entity whose colour you want to set, a colon and then a colour (using a name, hex-code or rgb declaration). Multiple colours can be set using multiple lines. For example:
Party 1: red
Party 2: #4455AA
Party 3: rgb(30,168,26)
link_opacity number
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_color_mode string
Text. Allowed values:
label_color color
.
label_outline_color_mode string
Outline. Allowed values:
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:
label_font_size number
In pixels.
label_font_size_min number
Min.
label_font_size_max number
Max.
label_bold boolean
Bold.
label_show_values boolean
Show node values. Allowed values:
label_show_values_links string
Show link values. Allowed values:
label_color_links color
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:
formatting.prefix string
Prefix. Text to place in front of number
formatting.suffix string
Suffix. Text to place after number
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.strip_zeros boolean
Remove trailing zeros.
formatting.strip_separator boolean
Hide thousands separator below 10,000. Turn off if you want four-digit numbers to include a separator, e.g. “1,234” rather than “1234”.
formatting.transform_labels boolean
Multiply/divide values.
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
Header
header.title string
Title.
header.subtitle string
Subtitle.
header.color color
Color.
header.align string
Alignment. Allowed values:
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.
Footer
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:
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.
