"""
Module for creating Sankey diagrams using Matplotlib.
"""
import logging
from types import SimpleNamespace
import numpy as np
import matplotlib as mpl
from matplotlib.path import Path
from matplotlib.patches import PathPatch
from matplotlib.transforms import Affine2D
from matplotlib import docstring
_log = logging.getLogger(__name__)
__author__ = "Kevin L. Davies"
__credits__ = ["Yannick Copin"]
__license__ = "BSD"
__version__ = "2011/09/16"
# Angles [deg/90]
RIGHT = 0
UP = 1
# LEFT = 2
DOWN = 3
[docs]class Sankey:
"""
Sankey diagram.
Sankey diagrams are a specific type of flow diagram, in which
the width of the arrows is shown proportionally to the flow
quantity. They are typically used to visualize energy or
material or cost transfers between processes.
`Wikipedia (6/1/2011) <https://en.wikipedia.org/wiki/Sankey_diagram>`_
"""
def __init__(self, ax=None, scale=1.0, unit='', format='%G', gap=0.25,
radius=0.1, shoulder=0.03, offset=0.15, head_angle=100,
margin=0.4, tolerance=1e-6, **kwargs):
"""
Create a new Sankey instance.
The optional arguments listed below are applied to all subdiagrams so
that there is consistent alignment and formatting.
In order to draw a complex Sankey diagram, create an instance of
:class:`Sankey` by calling it without any kwargs::
sankey = Sankey()
Then add simple Sankey sub-diagrams::
sankey.add() # 1
sankey.add() # 2
#...
sankey.add() # n
Finally, create the full diagram::
sankey.finish()
Or, instead, simply daisy-chain those calls::
Sankey().add().add... .add().finish()
Other Parameters
----------------
ax : `~.axes.Axes`
Axes onto which the data should be plotted. If *ax* isn't
provided, new Axes will be created.
scale : float
Scaling factor for the flows. *scale* sizes the width of the paths
in order to maintain proper layout. The same scale is applied to
all subdiagrams. The value should be chosen such that the product
of the scale and the sum of the inputs is approximately 1.0 (and
the product of the scale and the sum of the outputs is
approximately -1.0).
unit : str
The physical unit associated with the flow quantities. If *unit*
is None, then none of the quantities are labeled.
format : str
A Python number formatting string to be used in labeling the flow
as a quantity (i.e., a number times a unit, where the unit is
given).
gap : float
Space between paths that break in/break away to/from the top or
bottom.
radius : float
Inner radius of the vertical paths.
shoulder : float
Size of the shoulders of output arrows.
offset : float
Text offset (from the dip or tip of the arrow).
head_angle : float
Angle, in degrees, of the arrow heads (and negative of the angle of
the tails).
margin : float
Minimum space between Sankey outlines and the edge of the plot
area.
tolerance : float
Acceptable maximum of the magnitude of the sum of flows. The
magnitude of the sum of connected flows cannot be greater than
*tolerance*.
**kwargs
Any additional keyword arguments will be passed to :meth:`add`,
which will create the first subdiagram.
See Also
--------
Sankey.add
Sankey.finish
Examples
--------
.. plot:: gallery/specialty_plots/sankey_basics.py
"""
# Check the arguments.
if gap < 0:
raise ValueError(
"'gap' is negative, which is not allowed because it would "
"cause the paths to overlap")
if radius > gap:
raise ValueError(
"'radius' is greater than 'gap', which is not allowed because "
"it would cause the paths to overlap")
if head_angle < 0:
raise ValueError(
"'head_angle' is negative, which is not allowed because it "
"would cause inputs to look like outputs and vice versa")
if tolerance < 0:
raise ValueError(
"'tolerance' is negative, but it must be a magnitude")
# Create axes if necessary.
if ax is None:
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(1, 1, 1, xticks=[], yticks=[])
self.diagrams = []
# Store the inputs.
self.ax = ax
self.unit = unit
self.format = format
self.scale = scale
self.gap = gap
self.radius = radius
self.shoulder = shoulder
self.offset = offset
self.margin = margin
self.pitch = np.tan(np.pi * (1 - head_angle / 180.0) / 2.0)
self.tolerance = tolerance
# Initialize the vertices of tight box around the diagram(s).
self.extent = np.array((np.inf, -np.inf, np.inf, -np.inf))
# If there are any kwargs, create the first subdiagram.
if len(kwargs):
self.add(**kwargs)
def _arc(self, quadrant=0, cw=True, radius=1, center=(0, 0)):
"""
Return the codes and vertices for a rotated, scaled, and translated
90 degree arc.
Other Parameters
----------------
quadrant : {0, 1, 2, 3}, default: 0
Uses 0-based indexing (0, 1, 2, or 3).
cw : bool, default: True
If True, the arc vertices are produced clockwise; counter-clockwise
otherwise.
radius : float, default: 1
The radius of the arc.
center : (float, float), default: (0, 0)
(x, y) tuple of the arc's center.
"""
# Note: It would be possible to use matplotlib's transforms to rotate,
# scale, and translate the arc, but since the angles are discrete,
# it's just as easy and maybe more efficient to do it here.
ARC_CODES = [Path.LINETO,
Path.CURVE4,
Path.CURVE4,
Path.CURVE4,
Path.CURVE4,
Path.CURVE4,
Path.CURVE4]
# Vertices of a cubic Bezier curve approximating a 90 deg arc
# These can be determined by Path.arc(0, 90).
ARC_VERTICES = np.array([[1.00000000e+00, 0.00000000e+00],
[1.00000000e+00, 2.65114773e-01],
[8.94571235e-01, 5.19642327e-01],
[7.07106781e-01, 7.07106781e-01],
[5.19642327e-01, 8.94571235e-01],
[2.65114773e-01, 1.00000000e+00],
# Insignificant
# [6.12303177e-17, 1.00000000e+00]])
[0.00000000e+00, 1.00000000e+00]])
if quadrant == 0 or quadrant == 2:
if cw:
vertices = ARC_VERTICES
else:
vertices = ARC_VERTICES[:, ::-1] # Swap x and y.
elif quadrant == 1 or quadrant == 3:
# Negate x.
if cw:
# Swap x and y.
vertices = np.column_stack((-ARC_VERTICES[:, 1],
ARC_VERTICES[:, 0]))
else:
vertices = np.column_stack((-ARC_VERTICES[:, 0],
ARC_VERTICES[:, 1]))
if quadrant > 1:
radius = -radius # Rotate 180 deg.
return list(zip(ARC_CODES, radius * vertices +
np.tile(center, (ARC_VERTICES.shape[0], 1))))
def _add_input(self, path, angle, flow, length):
"""
Add an input to a path and return its tip and label locations.
"""
if angle is None:
return [0, 0], [0, 0]
else:
x, y = path[-1][1] # Use the last point as a reference.
dipdepth = (flow / 2) * self.pitch
if angle == RIGHT:
x -= length
dip = [x + dipdepth, y + flow / 2.0]
path.extend([(Path.LINETO, [x, y]),
(Path.LINETO, dip),
(Path.LINETO, [x, y + flow]),
(Path.LINETO, [x + self.gap, y + flow])])
label_location = [dip[0] - self.offset, dip[1]]
else: # Vertical
x -= self.gap
if angle == UP:
sign = 1
else:
sign = -1
dip = [x - flow / 2, y - sign * (length - dipdepth)]
if angle == DOWN:
quadrant = 2
else:
quadrant = 1
# Inner arc isn't needed if inner radius is zero
if self.radius:
path.extend(self._arc(quadrant=quadrant,
cw=angle == UP,
radius=self.radius,
center=(x + self.radius,
y - sign * self.radius)))
else:
path.append((Path.LINETO, [x, y]))
path.extend([(Path.LINETO, [x, y - sign * length]),
(Path.LINETO, dip),
(Path.LINETO, [x - flow, y - sign * length])])
path.extend(self._arc(quadrant=quadrant,
cw=angle == DOWN,
radius=flow + self.radius,
center=(x + self.radius,
y - sign * self.radius)))
path.append((Path.LINETO, [x - flow, y + sign * flow]))
label_location = [dip[0], dip[1] - sign * self.offset]
return dip, label_location
def _add_output(self, path, angle, flow, length):
"""
Append an output to a path and return its tip and label locations.
.. note:: *flow* is negative for an output.
"""
if angle is None:
return [0, 0], [0, 0]
else:
x, y = path[-1][1] # Use the last point as a reference.
tipheight = (self.shoulder - flow / 2) * self.pitch
if angle == RIGHT:
x += length
tip = [x + tipheight, y + flow / 2.0]
path.extend([(Path.LINETO, [x, y]),
(Path.LINETO, [x, y + self.shoulder]),
(Path.LINETO, tip),
(Path.LINETO, [x, y - self.shoulder + flow]),
(Path.LINETO, [x, y + flow]),
(Path.LINETO, [x - self.gap, y + flow])])
label_location = [tip[0] + self.offset, tip[1]]
else: # Vertical
x += self.gap
if angle == UP:
sign = 1
else:
sign = -1
tip = [x - flow / 2.0, y + sign * (length + tipheight)]
if angle == UP:
quadrant = 3
else:
quadrant = 0
# Inner arc isn't needed if inner radius is zero
if self.radius:
path.extend(self._arc(quadrant=quadrant,
cw=angle == UP,
radius=self.radius,
center=(x - self.radius,
y + sign * self.radius)))
else:
path.append((Path.LINETO, [x, y]))
path.extend([(Path.LINETO, [x, y + sign * length]),
(Path.LINETO, [x - self.shoulder,
y + sign * length]),
(Path.LINETO, tip),
(Path.LINETO, [x + self.shoulder - flow,
y + sign * length]),
(Path.LINETO, [x - flow, y + sign * length])])
path.extend(self._arc(quadrant=quadrant,
cw=angle == DOWN,
radius=self.radius - flow,
center=(x - self.radius,
y + sign * self.radius)))
path.append((Path.LINETO, [x - flow, y + sign * flow]))
label_location = [tip[0], tip[1] + sign * self.offset]
return tip, label_location
def _revert(self, path, first_action=Path.LINETO):
"""
A path is not simply reversible by path[::-1] since the code
specifies an action to take from the **previous** point.
"""
reverse_path = []
next_code = first_action
for code, position in path[::-1]:
reverse_path.append((next_code, position))
next_code = code
return reverse_path
# This might be more efficient, but it fails because 'tuple' object
# doesn't support item assignment:
# path[1] = path[1][-1:0:-1]
# path[1][0] = first_action
# path[2] = path[2][::-1]
# return path
[docs] @docstring.dedent_interpd
def add(self, patchlabel='', flows=None, orientations=None, labels='',
trunklength=1.0, pathlengths=0.25, prior=None, connect=(0, 0),
rotation=0, **kwargs):
"""
Add a simple Sankey diagram with flows at the same hierarchical level.
Parameters
----------
patchlabel : str
Label to be placed at the center of the diagram.
Note that *label* (not *patchlabel*) can be passed as keyword
argument to create an entry in the legend.
flows : list of float
Array of flow values. By convention, inputs are positive and
outputs are negative.
Flows are placed along the top of the diagram from the inside out
in order of their index within *flows*. They are placed along the
sides of the diagram from the top down and along the bottom from
the outside in.
If the sum of the inputs and outputs is
nonzero, the discrepancy will appear as a cubic Bezier curve along
the top and bottom edges of the trunk.
orientations : list of {-1, 0, 1}
List of orientations of the flows (or a single orientation to be
used for all flows). Valid values are 0 (inputs from
the left, outputs to the right), 1 (from and to the top) or -1
(from and to the bottom).
labels : list of (str or None)
List of labels for the flows (or a single label to be used for all
flows). Each label may be *None* (no label), or a labeling string.
If an entry is a (possibly empty) string, then the quantity for the
corresponding flow will be shown below the string. However, if
the *unit* of the main diagram is None, then quantities are never
shown, regardless of the value of this argument.
trunklength : float
Length between the bases of the input and output groups (in
data-space units).
pathlengths : list of float
List of lengths of the vertical arrows before break-in or after
break-away. If a single value is given, then it will be applied to
the first (inside) paths on the top and bottom, and the length of
all other arrows will be justified accordingly. The *pathlengths*
are not applied to the horizontal inputs and outputs.
prior : int
Index of the prior diagram to which this diagram should be
connected.
connect : (int, int)
A (prior, this) tuple indexing the flow of the prior diagram and
the flow of this diagram which should be connected. If this is the
first diagram or *prior* is *None*, *connect* will be ignored.
rotation : float
Angle of rotation of the diagram in degrees. The interpretation of
the *orientations* argument will be rotated accordingly (e.g., if
*rotation* == 90, an *orientations* entry of 1 means to/from the
left). *rotation* is ignored if this diagram is connected to an
existing one (using *prior* and *connect*).
Returns
-------
Sankey
The current `.Sankey` instance.
Other Parameters
----------------
**kwargs
Additional keyword arguments set `matplotlib.patches.PathPatch`
properties, listed below. For example, one may want to use
``fill=False`` or ``label="A legend entry"``.
%(Patch)s
See Also
--------
Sankey.finish
"""
# Check and preprocess the arguments.
if flows is None:
flows = np.array([1.0, -1.0])
else:
flows = np.array(flows)
n = flows.shape[0] # Number of flows
if rotation is None:
rotation = 0
else:
# In the code below, angles are expressed in deg/90.
rotation /= 90.0
if orientations is None:
orientations = 0
try:
orientations = np.broadcast_to(orientations, n)
except ValueError:
raise ValueError(
f"The shapes of 'flows' {np.shape(flows)} and 'orientations' "
f"{np.shape(orientations)} are incompatible"
) from None
try:
labels = np.broadcast_to(labels, n)
except ValueError:
raise ValueError(
f"The shapes of 'flows' {np.shape(flows)} and 'labels' "
f"{np.shape(labels)} are incompatible"
) from None
if trunklength < 0:
raise ValueError(
"'trunklength' is negative, which is not allowed because it "
"would cause poor layout")
if abs(np.sum(flows)) > self.tolerance:
_log.info("The sum of the flows is nonzero (%f; patchlabel=%r); "
"is the system not at steady state?",
np.sum(flows), patchlabel)
scaled_flows = self.scale * flows
gain = sum(max(flow, 0) for flow in scaled_flows)
loss = sum(min(flow, 0) for flow in scaled_flows)
if prior is not None:
if prior < 0:
raise ValueError("The index of the prior diagram is negative")
if min(connect) < 0:
raise ValueError(
"At least one of the connection indices is negative")
if prior >= len(self.diagrams):
raise ValueError(
f"The index of the prior diagram is {prior}, but there "
f"are only {len(self.diagrams)} other diagrams")
if connect[0] >= len(self.diagrams[prior].flows):
raise ValueError(
"The connection index to the source diagram is {}, but "
"that diagram has only {} flows".format(
connect[0], len(self.diagrams[prior].flows)))
if connect[1] >= n:
raise ValueError(
f"The connection index to this diagram is {connect[1]}, "
f"but this diagram has only {n} flows")
if self.diagrams[prior].angles[connect[0]] is None:
raise ValueError(
f"The connection cannot be made, which may occur if the "
f"magnitude of flow {connect[0]} of diagram {prior} is "
f"less than the specified tolerance")
flow_error = (self.diagrams[prior].flows[connect[0]] +
flows[connect[1]])
if abs(flow_error) >= self.tolerance:
raise ValueError(
f"The scaled sum of the connected flows is {flow_error}, "
f"which is not within the tolerance ({self.tolerance})")
# Determine if the flows are inputs.
are_inputs = [None] * n
for i, flow in enumerate(flows):
if flow >= self.tolerance:
are_inputs[i] = True
elif flow <= -self.tolerance:
are_inputs[i] = False
else:
_log.info(
"The magnitude of flow %d (%f) is below the tolerance "
"(%f).\nIt will not be shown, and it cannot be used in a "
"connection.", i, flow, self.tolerance)
# Determine the angles of the arrows (before rotation).
angles = [None] * n
for i, (orient, is_input) in enumerate(zip(orientations, are_inputs)):
if orient == 1:
if is_input:
angles[i] = DOWN
elif not is_input:
# Be specific since is_input can be None.
angles[i] = UP
elif orient == 0:
if is_input is not None:
angles[i] = RIGHT
else:
if orient != -1:
raise ValueError(
f"The value of orientations[{i}] is {orient}, "
f"but it must be -1, 0, or 1")
if is_input:
angles[i] = UP
elif not is_input:
angles[i] = DOWN
# Justify the lengths of the paths.
if np.iterable(pathlengths):
if len(pathlengths) != n:
raise ValueError(
f"The lengths of 'flows' ({n}) and 'pathlengths' "
f"({len(pathlengths)}) are incompatible")
else: # Make pathlengths into a list.
urlength = pathlengths
ullength = pathlengths
lrlength = pathlengths
lllength = pathlengths
d = dict(RIGHT=pathlengths)
pathlengths = [d.get(angle, 0) for angle in angles]
# Determine the lengths of the top-side arrows
# from the middle outwards.
for i, (angle, is_input, flow) in enumerate(zip(angles, are_inputs,
scaled_flows)):
if angle == DOWN and is_input:
pathlengths[i] = ullength
ullength += flow
elif angle == UP and not is_input:
pathlengths[i] = urlength
urlength -= flow # Flow is negative for outputs.
# Determine the lengths of the bottom-side arrows
# from the middle outwards.
for i, (angle, is_input, flow) in enumerate(reversed(list(zip(
angles, are_inputs, scaled_flows)))):
if angle == UP and is_input:
pathlengths[n - i - 1] = lllength
lllength += flow
elif angle == DOWN and not is_input:
pathlengths[n - i - 1] = lrlength
lrlength -= flow
# Determine the lengths of the left-side arrows
# from the bottom upwards.
has_left_input = False
for i, (angle, is_input, spec) in enumerate(reversed(list(zip(
angles, are_inputs, zip(scaled_flows, pathlengths))))):
if angle == RIGHT:
if is_input:
if has_left_input:
pathlengths[n - i - 1] = 0
else:
has_left_input = True
# Determine the lengths of the right-side arrows
# from the top downwards.
has_right_output = False
for i, (angle, is_input, spec) in enumerate(zip(
angles, are_inputs, list(zip(scaled_flows, pathlengths)))):
if angle == RIGHT:
if not is_input:
if has_right_output:
pathlengths[i] = 0
else:
has_right_output = True
# Begin the subpaths, and smooth the transition if the sum of the flows
# is nonzero.
urpath = [(Path.MOVETO, [(self.gap - trunklength / 2.0), # Upper right
gain / 2.0]),
(Path.LINETO, [(self.gap - trunklength / 2.0) / 2.0,
gain / 2.0]),
(Path.CURVE4, [(self.gap - trunklength / 2.0) / 8.0,
gain / 2.0]),
(Path.CURVE4, [(trunklength / 2.0 - self.gap) / 8.0,
-loss / 2.0]),
(Path.LINETO, [(trunklength / 2.0 - self.gap) / 2.0,
-loss / 2.0]),
(Path.LINETO, [(trunklength / 2.0 - self.gap),
-loss / 2.0])]
llpath = [(Path.LINETO, [(trunklength / 2.0 - self.gap), # Lower left
loss / 2.0]),
(Path.LINETO, [(trunklength / 2.0 - self.gap) / 2.0,
loss / 2.0]),
(Path.CURVE4, [(trunklength / 2.0 - self.gap) / 8.0,
loss / 2.0]),
(Path.CURVE4, [(self.gap - trunklength / 2.0) / 8.0,
-gain / 2.0]),
(Path.LINETO, [(self.gap - trunklength / 2.0) / 2.0,
-gain / 2.0]),
(Path.LINETO, [(self.gap - trunklength / 2.0),
-gain / 2.0])]
lrpath = [(Path.LINETO, [(trunklength / 2.0 - self.gap), # Lower right
loss / 2.0])]
ulpath = [(Path.LINETO, [self.gap - trunklength / 2.0, # Upper left
gain / 2.0])]
# Add the subpaths and assign the locations of the tips and labels.
tips = np.zeros((n, 2))
label_locations = np.zeros((n, 2))
# Add the top-side inputs and outputs from the middle outwards.
for i, (angle, is_input, spec) in enumerate(zip(
angles, are_inputs, list(zip(scaled_flows, pathlengths)))):
if angle == DOWN and is_input:
tips[i, :], label_locations[i, :] = self._add_input(
ulpath, angle, *spec)
elif angle == UP and not is_input:
tips[i, :], label_locations[i, :] = self._add_output(
urpath, angle, *spec)
# Add the bottom-side inputs and outputs from the middle outwards.
for i, (angle, is_input, spec) in enumerate(reversed(list(zip(
angles, are_inputs, list(zip(scaled_flows, pathlengths)))))):
if angle == UP and is_input:
tip, label_location = self._add_input(llpath, angle, *spec)
tips[n - i - 1, :] = tip
label_locations[n - i - 1, :] = label_location
elif angle == DOWN and not is_input:
tip, label_location = self._add_output(lrpath, angle, *spec)
tips[n - i - 1, :] = tip
label_locations[n - i - 1, :] = label_location
# Add the left-side inputs from the bottom upwards.
has_left_input = False
for i, (angle, is_input, spec) in enumerate(reversed(list(zip(
angles, are_inputs, list(zip(scaled_flows, pathlengths)))))):
if angle == RIGHT and is_input:
if not has_left_input:
# Make sure the lower path extends
# at least as far as the upper one.
if llpath[-1][1][0] > ulpath[-1][1][0]:
llpath.append((Path.LINETO, [ulpath[-1][1][0],
llpath[-1][1][1]]))
has_left_input = True
tip, label_location = self._add_input(llpath, angle, *spec)
tips[n - i - 1, :] = tip
label_locations[n - i - 1, :] = label_location
# Add the right-side outputs from the top downwards.
has_right_output = False
for i, (angle, is_input, spec) in enumerate(zip(
angles, are_inputs, list(zip(scaled_flows, pathlengths)))):
if angle == RIGHT and not is_input:
if not has_right_output:
# Make sure the upper path extends
# at least as far as the lower one.
if urpath[-1][1][0] < lrpath[-1][1][0]:
urpath.append((Path.LINETO, [lrpath[-1][1][0],
urpath[-1][1][1]]))
has_right_output = True
tips[i, :], label_locations[i, :] = self._add_output(
urpath, angle, *spec)
# Trim any hanging vertices.
if not has_left_input:
ulpath.pop()
llpath.pop()
if not has_right_output:
lrpath.pop()
urpath.pop()
# Concatenate the subpaths in the correct order (clockwise from top).
path = (urpath + self._revert(lrpath) + llpath + self._revert(ulpath) +
[(Path.CLOSEPOLY, urpath[0][1])])
# Create a patch with the Sankey outline.
codes, vertices = zip(*path)
vertices = np.array(vertices)
def _get_angle(a, r):
if a is None:
return None
else:
return a + r
if prior is None:
if rotation != 0: # By default, none of this is needed.
angles = [_get_angle(angle, rotation) for angle in angles]
rotate = Affine2D().rotate_deg(rotation * 90).transform_affine
tips = rotate(tips)
label_locations = rotate(label_locations)
vertices = rotate(vertices)
text = self.ax.text(0, 0, s=patchlabel, ha='center', va='center')
else:
rotation = (self.diagrams[prior].angles[connect[0]] -
angles[connect[1]])
angles = [_get_angle(angle, rotation) for angle in angles]
rotate = Affine2D().rotate_deg(rotation * 90).transform_affine
tips = rotate(tips)
offset = self.diagrams[prior].tips[connect[0]] - tips[connect[1]]
translate = Affine2D().translate(*offset).transform_affine
tips = translate(tips)
label_locations = translate(rotate(label_locations))
vertices = translate(rotate(vertices))
kwds = dict(s=patchlabel, ha='center', va='center')
text = self.ax.text(*offset, **kwds)
if mpl.rcParams['_internal.classic_mode']:
fc = kwargs.pop('fc', kwargs.pop('facecolor', '#bfd1d4'))
lw = kwargs.pop('lw', kwargs.pop('linewidth', 0.5))
else:
fc = kwargs.pop('fc', kwargs.pop('facecolor', None))
lw = kwargs.pop('lw', kwargs.pop('linewidth', None))
if fc is None:
fc = next(self.ax._get_patches_for_fill.prop_cycler)['color']
patch = PathPatch(Path(vertices, codes), fc=fc, lw=lw, **kwargs)
self.ax.add_patch(patch)
# Add the path labels.
texts = []
for number, angle, label, location in zip(flows, angles, labels,
label_locations):
if label is None or angle is None:
label = ''
elif self.unit is not None:
quantity = self.format % abs(number) + self.unit
if label != '':
label += "\n"
label += quantity
texts.append(self.ax.text(x=location[0], y=location[1],
s=label,
ha='center', va='center'))
# Text objects are placed even they are empty (as long as the magnitude
# of the corresponding flow is larger than the tolerance) in case the
# user wants to provide labels later.
# Expand the size of the diagram if necessary.
self.extent = (min(np.min(vertices[:, 0]),
np.min(label_locations[:, 0]),
self.extent[0]),
max(np.max(vertices[:, 0]),
np.max(label_locations[:, 0]),
self.extent[1]),
min(np.min(vertices[:, 1]),
np.min(label_locations[:, 1]),
self.extent[2]),
max(np.max(vertices[:, 1]),
np.max(label_locations[:, 1]),
self.extent[3]))
# Include both vertices _and_ label locations in the extents; there are
# where either could determine the margins (e.g., arrow shoulders).
# Add this diagram as a subdiagram.
self.diagrams.append(
SimpleNamespace(patch=patch, flows=flows, angles=angles, tips=tips,
text=text, texts=texts))
# Allow a daisy-chained call structure (see docstring for the class).
return self
[docs] def finish(self):
"""
Adjust the axes and return a list of information about the Sankey
subdiagram(s).
Return value is a list of subdiagrams represented with the following
fields:
=============== ===================================================
Field Description
=============== ===================================================
*patch* Sankey outline (an instance of
:class:`~matplotlib.patches.PathPatch`)
*flows* values of the flows (positive for input, negative
for output)
*angles* list of angles of the arrows [deg/90]
For example, if the diagram has not been rotated,
an input to the top side will have an angle of 3
(DOWN), and an output from the top side will have
an angle of 1 (UP). If a flow has been skipped
(because its magnitude is less than *tolerance*),
then its angle will be *None*.
*tips* array in which each row is an [x, y] pair
indicating the positions of the tips (or "dips") of
the flow paths
If the magnitude of a flow is less the *tolerance*
for the instance of :class:`Sankey`, the flow is
skipped and its tip will be at the center of the
diagram.
*text* :class:`~matplotlib.text.Text` instance for the
label of the diagram
*texts* list of :class:`~matplotlib.text.Text` instances
for the labels of flows
=============== ===================================================
See Also
--------
Sankey.add
"""
self.ax.axis([self.extent[0] - self.margin,
self.extent[1] + self.margin,
self.extent[2] - self.margin,
self.extent[3] + self.margin])
self.ax.set_aspect('equal', adjustable='datalim')
return self.diagrams
