6.2.5 Sankey Chart

Sankey diagrams visualize the contributions to flow by defining source to represent the source node, target for the target node, value to set the flow volume, and label that shows the node name.

if a flow is twice as wide it represents double the quantity. Flows in the diagram can show e.g. energy, materials, water, or costs.

• The link is a dictionary containing data about the connections we want to draw.

• The source and target are lists of indexes for the nodes Plotly will connect.

• The value is a list of numbers that will define the width of these connections.

1. Basic Sankey Chart

label = ["ZERO", "ONE", "TWO", "THREE", "FOUR", "FIVE"]
source = [0, 0, 1, 1, 0]
target = [2, 3, 3, 5, 4]
value = [8, 3, 2, 8, 4]

link = dict(source = source, target = target, value = value)
node = dict(label = label, pad=50, thickness=5)
data = go.Sankey(link = link, node=node)

fig = go.Figure(data)
fig.show()

2. Customized Sankey Chart

label = ["ZERO", "ONE", "TWO", "THREE", "FOUR", "FIVE"]
source = [0, 0, 1, 1, 0]
target = [2, 3, 3, 5, 4]
value = [8, 3, 2, 8, 4]

# add color list
colors = ['#F27420','#4994CE','#FABC13','#7FC241','#EC2272']

# data to dict, dict to sankey
link = dict(source = source, target = target, value = value,color = colors)
node = dict(label = label, pad=50, thickness=5)
data = go.Sankey(link = link, node=node)
# plot
fig = go.Figure(data)
fig.update_layout(height=600,font_size = 14) # set figure and font size
fig.show()

3. Vertical Sankey Chart

It's very easy to make the chart in vertical, just address orientation = 'v'. However, the horizontal Sankey chart is in common use.

link = dict(source = source, target = target, value = value,color = colors)
node = dict(label = label, pad=50, thickness=5)
data = go.Sankey(link = link, node=node, orientation = 'v')
# plot
fig = go.Figure(data)