def draw_graph(G,
labels=None,
node_colors=None,
node_shapes=None,
node_scale=1.0,
edge_style='solid',
edge_cmap=None,
colorbar=False,
vrange=None,
layout=None,
title=None,
font_family='sans-serif',
font_size=9,
stretch_factor=1.0,
edge_alpha=True,
fig_size=None):
"""Draw a weighted graph with options to visualize link weights.
The resulting diagram uses the rank of each node as its size, and the
weight of each link (after discarding thresholded values, see below) as the
link opacity.
It maps edge weight to color as well as line opacity and thickness,
allowing the color part to be hardcoded over a value range (to permit valid
cross-figure comparisons for different graphs, so the same color
corresponds to the same link weight even if each graph has a different
range of weights). The nodes sizes are proportional to their degree,
computed as the sum of the weights of all their links. The layout defaults
to circular, but any nx layout function can be passed in, as well as a
statically precomputed layout.
Parameters
----------
G : weighted graph
The values must be of the form (v1,v2), with all v2 in [0,1]. v1 are
used for colors, v2 for thickness/opacity.
labels : list or dict, optional.
An indexable object that maps nodes to strings. If not given, the
string form of each node is used as a label. If False, no labels are
drawn.
node_colors : list or dict, optional.
An indexable object that maps nodes to valid matplotlib color specs. See
matplotlib's plot() function for details.
node_shapes : list or dict, optional.
An indexable object that maps nodes to valid matplotlib shape specs. See
matplotlib's scatter() function for details. If not given, circles are
used.
node_scale : float, optional
A scale factor to globally stretch or shrink all nodes symbols by.
edge_style : string, optional
Line style for the edges, defaults to 'solid'.
edge_cmap : matplotlib colormap, optional.
A callable that returns valid color specs, like matplotlib colormaps.
If not given, edges are colored black.
colorbar : bool
If true, automatically add a colorbar showing the mapping of graph weight
values to colors.
vrange : pair of floats
If given, this indicates the total range of values that the weights can
in principle occupy, and is used to set the lower/upper range of the
colormap. This allows you to set the range of multiple different figures
to the same values, even if each individual graph has range variations,
so that visual color comparisons across figures are valid.
layout : function or layout dict, optional
A NetworkX-like layout function or the result of a precomputed layout for
the given graph. NetworkX produces layouts as dicts keyed by nodes and
with (x,y) pairs of coordinates as values, any function that produces
this kind of output is acceptable. Defaults to nx.circular_layout.
title : string, optional.
If given, title to put on the main plot.
font_family : string, optional.
Font family used for the node labels and title.
font_size : int, optional.
Font size used for the node labels and title.
stretch_factor : float, optional
A global scaling factor to make the graph larger (or smaller if <1).
This can be used to separate the nodes if they start overlapping.
edge_alpha: bool, optional
Whether to weight the transparency of each edge by a factor equivalent to
its relative weight
fig_size: list of height by width, the size of the figure (in
inches). Defaults to [6,6]
Returns
-------
fig
The matplotlib figure object with the plot.
"""
if fig_size is None:
figsize = [6, 6]
scaler = figsize[0] / 6.
# For the size of the node symbols
node_size_base = 1000 * scaler
node_min_size = 200 * scaler
default_node_shape = 'o'
# Default colors if none given
default_node_color = 'r'
default_edge_color = 'k'
# Max edge width
max_width = 13 * scaler
min_width = 2 * scaler
font_family = 'sans-serif'
# We'll use the nodes a lot, let's make a numpy array of them
nodes = np.array(sorted(G.nodes()))
nnod = len(nodes)
# Build a 'weighted degree' array obtained by adding the (absolute value)
# of the weights for all edges pointing to each node:
amat = nx.adj_matrix(G).A # get a normal array out of it
degarr = abs(amat).sum(0) # weights are sums across rows
# Map the degree to the 0-1 range so we can use it for sizing the nodes.
try:
odegree = rescale_arr(degarr, 0, 1)
# Make an array of node sizes based on node degree
node_sizes = odegree * node_size_base + node_min_size
except ZeroDivisionError:
# All nodes same size
node_sizes = np.empty(nnod, float)
node_sizes.fill(0.5 * node_size_base + node_min_size)
# Adjust node size list. We square the scale factor because in mpl, node
# sizes represent area, not linear size, but it's more intuitive for the
# user to think of linear factors (the overall figure scale factor is also
# linear).
node_sizes *= node_scale ** 2
# Set default node properties
if node_colors is None:
node_colors = [default_node_color] * nnod
if node_shapes is None:
node_shapes = [default_node_shape] * nnod
# Set default edge colormap
if edge_cmap is None:
# Make an object with the colormap API, that maps all input values to
# the default color (with proper alhpa)
edge_cmap = (lambda val, alpha:
colors.colorConverter.to_rgba(default_edge_color, alpha))
# if vrange is None, we set the color range from the values, else the user
# can specify it
# e[2] is edge value: edges_iter returns (i,j,data)
gvals = np.array([e[2]['weight'] for e in G.edges(data=True)])
gvmin, gvmax = gvals.min(), gvals.max()
gvrange = gvmax - gvmin
if vrange is None:
vrange = gvmin, gvmax
# Now, construct the normalization for the colormap
cnorm = mpl.colors.Normalize(vmin=vrange[0], vmax=vrange[1])
# Create the actual plot where the graph will be displayed
figsize = np.array(figsize, float)
figsize *= stretch_factor
fig = plt.figure(figsize=figsize)
ax_graph = fig.add_subplot(1, 1, 1)
fig.sca(ax_graph)
if layout is None:
layout = nx.circular_layout
# Compute positions for all nodes - nx has several algorithms
if callable(layout):
pos = layout(G)
else:
# The user can also provide a precomputed layout
pos = layout
# Draw nodes
for nod in nodes:
nx.draw_networkx_nodes(G,
pos,
nodelist=[nod],
node_color=node_colors[nod],
node_shape=node_shapes[nod],
node_size=node_sizes[nod],
edgecolors='k')
# Draw edges
if not isinstance(G, nx.DiGraph):
# Undirected graph, simple lines for edges
# We need the size of the value range to properly scale colors
vsize = vrange[1] - vrange[0]
gvals_normalized = G.metadata['vals_norm']
for (u, v, y) in G.edges(data=True):
# The graph value is the weight, and the normalized values are in
# [0,1], used for thickness/transparency
alpha = gvals_normalized[u, v]
# Scale the color choice to the specified vrange, so that
ecol = (y['weight'] - vrange[0]) / vsize
#print 'u,v:',u,v,'y:',y,'ecol:',ecol # dbg
if edge_alpha:
fade = alpha
else:
fade = 1.0
edge_color = [tuple(edge_cmap(ecol, fade))]
#dbg:
#print u,v,y
nx.draw_networkx_edges(G,
pos,
edgelist=[(u, v)],
width=min_width + alpha * max_width,
edge_color=edge_color,
style=edge_style)
else:
# Directed graph, use arrows.
# XXX - this is currently broken.
raise NotImplementedError("arrow drawing currently broken")
## for (u,v,x) in G.edges(data=True):
## y,w = x
## draw_arrows(G,pos,edgelist=[(u,v)],
## edge_color=[w],
## alpha=w,
## edge_cmap=edge_cmap,
## width=w*max_width)
# Draw labels. If not given, we use the string form of the nodes. If
# labels is False, no labels are drawn.
if labels is None:
labels = map(str, nodes)
if labels:
lab_idx = list(range(len(labels)))
labels_dict = dict(zip(lab_idx, labels))
nx.draw_networkx_labels(G,
pos,
labels_dict,
font_size=font_size,
font_family=font_family)
if title:
plt.title(title, fontsize=font_size)
# Turn off x and y axes labels in pylab
plt.xticks([])
plt.yticks([])
# Add a colorbar if requested
if colorbar:
divider = make_axes_locatable(ax_graph)
ax_cb = divider.new_vertical(size="20%", pad=0.2, pack_start=True)
fig.add_axes(ax_cb)
cb = mpl.colorbar.ColorbarBase(ax_cb,
cmap=edge_cmap,
norm=cnorm,
#boundaries = np.linspace(min((gvmin,0)),
# max((gvmax,0)),
# 256),
orientation='horizontal',
format='%.2f')
# Always return the MPL figure object so the user can further manipulate it
return fig
def draw_graph(G,
labels=None,
node_colors=None,
node_shapes=None,
node_scale=1.0,
edge_style='solid',
edge_cmap=None,
colorbar=False,
vrange=None,
layout=None,
title=None,
font_family='sans-serif',
font_size=9,
stretch_factor=1.0,
edge_alpha=True,
fig_size=None):
"""Draw a weighted graph with options to visualize link weights.
The resulting diagram uses the rank of each node as its size, and the
weight of each link (after discarding thresholded values, see below) as the
link opacity.
It maps edge weight to color as well as line opacity and thickness,
allowing the color part to be hardcoded over a value range (to permit valid
cross-figure comparisons for different graphs, so the same color
corresponds to the same link weight even if each graph has a different
range of weights). The nodes sizes are proportional to their degree,
computed as the sum of the weights of all their links. The layout defaults
to circular, but any nx layout function can be passed in, as well as a
statically precomputed layout.
Parameters
----------
G : weighted graph
The values must be of the form (v1,v2), with all v2 in [0,1]. v1 are
used for colors, v2 for thickness/opacity.
labels : list or dict, optional.
An indexable object that maps nodes to strings. If not given, the
string form of each node is used as a label. If False, no labels are
drawn.
node_colors : list or dict, optional.
An indexable object that maps nodes to valid matplotlib color specs. See
matplotlib's plot() function for details.
node_shapes : list or dict, optional.
An indexable object that maps nodes to valid matplotlib shape specs. See
matplotlib's scatter() function for details. If not given, circles are
used.
node_scale : float, optional
A scale factor to globally stretch or shrink all nodes symbols by.
edge_style : string, optional
Line style for the edges, defaults to 'solid'.
edge_cmap : matplotlib colormap, optional.
A callable that returns valid color specs, like matplotlib colormaps.
If not given, edges are colored black.
colorbar : bool
If true, automatically add a colorbar showing the mapping of graph weight
values to colors.
vrange : pair of floats
If given, this indicates the total range of values that the weights can
in principle occupy, and is used to set the lower/upper range of the
colormap. This allows you to set the range of multiple different figures
to the same values, even if each individual graph has range variations,
so that visual color comparisons across figures are valid.
layout : function or layout dict, optional
A NetworkX-like layout function or the result of a precomputed layout for
the given graph. NetworkX produces layouts as dicts keyed by nodes and
with (x,y) pairs of coordinates as values, any function that produces
this kind of output is acceptable. Defaults to nx.circular_layout.
title : string, optional.
If given, title to put on the main plot.
font_family : string, optional.
Font family used for the node labels and title.
font_size : int, optional.
Font size used for the node labels and title.
stretch_factor : float, optional
A global scaling factor to make the graph larger (or smaller if <1).
This can be used to separate the nodes if they start overlapping.
edge_alpha: bool, optional
Whether to weight the transparency of each edge by a factor equivalent to
its relative weight
fig_size: list of height by width, the size of the figure (in
inches). Defaults to [6,6]
Returns
-------
fig
The matplotlib figure object with the plot.
"""
if fig_size is None:
figsize = [6, 6]
scaler = figsize[0] / 6.
# For the size of the node symbols
node_size_base = 1000 * scaler
node_min_size = 200 * scaler
default_node_shape = 'o'
# Default colors if none given
default_node_color = 'r'
default_edge_color = 'k'
# Max edge width
max_width = 13 * scaler
min_width = 2 * scaler
font_family = 'sans-serif'
# We'll use the nodes a lot, let's make a numpy array of them
nodes = np.array(sorted(G.nodes()))
nnod = len(nodes)
# Build a 'weighted degree' array obtained by adding the (absolute value)
# of the weights for all edges pointing to each node:
amat = nx.adj_matrix(G).A # get a normal array out of it
degarr = abs(amat).sum(0) # weights are sums across rows
# Map the degree to the 0-1 range so we can use it for sizing the nodes.
try:
odegree = rescale_arr(degarr, 0, 1)
# Make an array of node sizes based on node degree
node_sizes = odegree * node_size_base + node_min_size
except ZeroDivisionError:
# All nodes same size
node_sizes = np.empty(nnod, float)
node_sizes.fill(0.5 * node_size_base + node_min_size)
# Adjust node size list. We square the scale factor because in mpl, node
# sizes represent area, not linear size, but it's more intuitive for the
# user to think of linear factors (the overall figure scale factor is also
# linear).
node_sizes *= node_scale**2
# Set default node properties
if node_colors is None:
node_colors = [default_node_color] * nnod
if node_shapes is None:
node_shapes = [default_node_shape] * nnod
# Set default edge colormap
if edge_cmap is None:
# Make an object with the colormap API, that maps all input values to
# the default color (with proper alhpa)
edge_cmap = (lambda val, alpha: colors.colorConverter.to_rgba(
default_edge_color, alpha))
# if vrange is None, we set the color range from the values, else the user
# can specify it
# e[2] is edge value: edges_iter returns (i,j,data)
gvals = np.array([e[2]['weight'] for e in G.edges(data=True)])
gvmin, gvmax = gvals.min(), gvals.max()
gvrange = gvmax - gvmin
if vrange is None:
vrange = gvmin, gvmax
# Now, construct the normalization for the colormap
cnorm = mpl.colors.Normalize(vmin=vrange[0], vmax=vrange[1])
# Create the actual plot where the graph will be displayed
figsize = np.array(figsize, float)
figsize *= stretch_factor
fig = plt.figure(figsize=figsize)
ax_graph = fig.add_subplot(1, 1, 1)
fig.sca(ax_graph)
if layout is None:
layout = nx.circular_layout
# Compute positions for all nodes - nx has several algorithms
if callable(layout):
pos = layout(G)
else:
# The user can also provide a precomputed layout
pos = layout
# Draw nodes
for nod in nodes:
nx.draw_networkx_nodes(G,
pos,
nodelist=[nod],
node_color=node_colors[nod],
node_shape=node_shapes[nod],
node_size=node_sizes[nod])
# Draw edges
if not isinstance(G, nx.DiGraph):
# Undirected graph, simple lines for edges
# We need the size of the value range to properly scale colors
vsize = vrange[1] - vrange[0]
gvals_normalized = G.metadata['vals_norm']
for (u, v, y) in G.edges(data=True):
# The graph value is the weight, and the normalized values are in
# [0,1], used for thickness/transparency
alpha = gvals_normalized[u, v]
# Scale the color choice to the specified vrange, so that
ecol = (y['weight'] - vrange[0]) / vsize
#print 'u,v:',u,v,'y:',y,'ecol:',ecol # dbg
if edge_alpha:
fade = alpha
else:
fade = 1.0
edge_color = [tuple(edge_cmap(ecol, fade))]
#dbg:
#print u,v,y
draw_networkx_edges(G,
pos,
edgelist=[(u, v)],
width=min_width + alpha * max_width,
edge_color=edge_color,
style=edge_style)
else:
# Directed graph, use arrows.
# XXX - this is currently broken.
raise NotImplementedError("arrow drawing currently broken")
## for (u,v,x) in G.edges(data=True):
## y,w = x
## draw_arrows(G,pos,edgelist=[(u,v)],
## edge_color=[w],
## alpha=w,
## edge_cmap=edge_cmap,
## width=w*max_width)
# Draw labels. If not given, we use the string form of the nodes. If
# labels is False, no labels are drawn.
if labels is None:
labels = map(str, nodes)
if labels:
lab_idx = range(len(labels))
labels_dict = dict(zip(lab_idx, labels))
nx.draw_networkx_labels(G,
pos,
labels_dict,
font_size=font_size,
font_family=font_family)
if title:
plt.title(title, fontsize=font_size)
# Turn off x and y axes labels in pylab
plt.xticks([])
plt.yticks([])
# Add a colorbar if requested
if colorbar:
divider = make_axes_locatable(ax_graph)
ax_cb = divider.new_vertical(size="20%", pad=0.2, pack_start=True)
fig.add_axes(ax_cb)
cb = mpl.colorbar.ColorbarBase(
ax_cb,
cmap=edge_cmap,
norm=cnorm,
#boundaries = np.linspace(min((gvmin,0)),
# max((gvmax,0)),
# 256),
orientation='horizontal',
format='%.2f')
# Always return the MPL figure object so the user can further manipulate it
return fig