Sankey with Matplotlib - pandas

Question

In this Senkey are two Inputs: K and S, three Outputs: H,F and Sp and the Rest: x
The Inputs shall come from the left Side, the Outputs go to the right Side.
The Rest shall go to the Top.
from matplotlib.sankey import Sankey
import matplotlib.pyplot as plt
fig = plt.figure(figsize = [10,10])
ax = fig.add_subplot(1,1,1)
ax.set(yticklabels=[],xticklabels=[])
ax.text(-10,10, "xxx")
Sankey(ax=ax, flows = [ 20400,3000,-19900,-400,-2300,800],
labels = ['K', 'S', 'H', 'F', 'Sp', 'x'],
orientations = [ 1, -1, 1, 0, -1, -1 ],
scale=1, margin=100, trunklength=1.0).finish()
plt.tight_layout()
plt.show()
I played a lot with the orientations, but nothing works or looks nice.
And, it there a way to set different colors for every arrow?

Answer 1

The scale of the Sankey should be such that input-flow times scale is about 1.0 and output-flow times scale is about -1.0 (see docs). Therefore, about 1/25000 is a good starting point for experimentation. The margin should be a small number, maybe around 1, or leave it out. I think the only way to have individual colors, is to chain multiple Sankeys together (with add), but that's probably not what you want. Use plt.axis("off") to suppress the axes completely.
My test code:
from matplotlib.sankey import Sankey
import matplotlib.pyplot as plt
fig = plt.figure(figsize = [10,10])
ax = fig.add_subplot(1,1,1)
Sankey(ax=ax, flows = [ 20400,3000,-19900,-400,-2300,-800],
labels = ['K', 'S', 'H', 'F', 'Sp', 'x'],
orientations = [ 1, -1, 1, 0, -1, -1 ],
scale=1/25000, trunklength=1,
edgecolor = '#099368', facecolor = '#099368'
).finish()
plt.axis("off")
plt.show()
Generated Sankey:

Answer 2

With different Colors
from matplotlib.sankey import Sankey
import matplotlib.pyplot as plt
from matplotlib import rcParams
plt.rc('font', family = 'serif')
plt.rcParams['font.size'] = 10
plt.rcParams['font.serif'] = "Linux Libertine"
fig = plt.figure(figsize = [6,4], dpi = 330)
ax = fig.add_subplot(1, 1, 1,)
s = Sankey(ax = ax, scale = 1/40000, unit = 'kg', gap = .4, shoulder = 0.05,)
s.add(
flows = [3000, 20700, -23700,],
orientations = [ 1, 1, 0, ],
labels = ["S Value", "K Value", None, ],
trunklength = 1, pathlengths = 0.4, edgecolor = '#000000', facecolor = 'darkgreen',
lw = 0.5,
)
s.add(
flows = [23700, -800, -2400, -20500],
orientations = [0, 1, -1, 0],
labels = [None, "U Value", "Sp Value", None],
trunklength=1.5, pathlengths=0.5, edgecolor = '#000000', facecolor = 'grey',
prior = 0, connect = (2,0), lw = 0.5,
)
s.add(
flows = [20500, -20000, -500],
orientations = [0, -1, -1],
labels = [None, "H Value", "F Value"],
trunklength =1, pathlengths = 0.5, edgecolor = '#000000', facecolor = 'darkred',
prior = 1, connect = (3,0), lw = 0.5,
)
diagrams = s.finish()
for d in diagrams:
for t in d.texts:
t.set_horizontalalignment('left')
diagrams[0].texts[0].set_position(xy = [-0.58, 0.9,]) # S
diagrams[0].texts[1].set_position(xy = [-1.5, 0.9,]) # K
diagrams[2].texts[1].set_position(xy = [ 2.35, -1.2,]) # H
diagrams[2].texts[2].set_position(xy = [ 1.75, -1.2,]) # F
diagrams[1].texts[2].set_position(xy = [ 0.7, -1.2]) # Sp
diagrams[1].texts[1].set_position(xy = [ 0.7, 0.9,]) # U
# print(diagrams[0].texts[0])
# print(diagrams[0].texts[1])
# print(diagrams[1].texts[0])
# print(diagrams[1].texts[1])
# print(diagrams[1].texts[2])
# print(diagrams[2].texts[0])
# print(diagrams[2].texts[1])
# print(diagrams[2].texts[2])
plt.axis("off")
plt.show()