import numpy as np
from statsmodels.compat import range
from . import utils
[docs]def dot_plot(points, intervals=None, lines=None, sections=None,
styles=None, marker_props=None, line_props=None,
split_names=None, section_order=None, line_order=None,
stacked=False, styles_order=None, striped=False,
horizontal=True, ax=None):
"""
Produce a dotplot similar in style to those in Cleveland's
"Visualizing Data" book. These are also known as "forest plots".
Parameters
----------
points : array_like
The quantitative values to be plotted as markers.
intervals : array_like
The intervals to be plotted around the points. The elements
of `intervals` are either scalars or sequences of length 2. A
scalar indicates the half width of a symmetric interval. A
sequence of length 2 contains the left and right half-widths
(respectively) of a nonsymmetric interval. If None, no
intervals are drawn.
lines : array_like
A grouping variable indicating which points/intervals are
drawn on a common line. If None, each point/interval appears
on its own line.
sections : array_like
A grouping variable indicating which lines are grouped into
sections. If None, everything is drawn in a single section.
styles : array_like
A grouping label defining the plotting style of the markers
and intervals.
marker_props : dict
A dictionary mapping style codes (the values in `styles`) to
dictionaries defining key/value pairs to be passed as keyword
arguments to `plot` when plotting markers. Useful keyword
arguments are "color", "marker", and "ms" (marker size).
line_props : dict
A dictionary mapping style codes (the values in `styles`) to
dictionaries defining key/value pairs to be passed as keyword
arguments to `plot` when plotting interval lines. Useful
keyword arguments are "color", "linestyle", "solid_capstyle",
and "linewidth".
split_names : string
If not None, this is used to split the values of `lines` into
substrings that are drawn in the left and right margins,
respectively. If None, the values of `lines` are drawn in the
left margin.
section_order : array_like
The section labels in the order in which they appear in the
dotplot.
line_order : array_like
The line labels in the order in which they appear in the
dotplot.
stacked : boolean
If True, when multiple points or intervals are drawn on the
same line, they are offset from each other.
styles_order : array_like
If stacked=True, this is the order in which the point styles
on a given line are drawn from top to bottom (if horizontal
is True) or from left to right (if horiontal is False). If
None (default), the order is lexical.
striped : boolean
If True, every other line is enclosed in a shaded box.
horizontal : boolean
If True (default), the lines are drawn horizontally, otherwise
they are drawn vertically.
ax : matplotlib.axes
The axes on which the dotplot is drawn. If None, a new axes
is created.
Returns
-------
fig : Figure
The figure given by `ax.figure` or a new instance.
Notes
-----
`points`, `intervals`, `lines`, `sections`, `styles` must all have
the same length whenever present.
Examples
--------
This is a simple dotplot with one point per line:
>>> dot_plot(points=point_values)
This dotplot has labels on the lines (if elements in
`label_values` are repeated, the correponding points appear on the
same line):
>>> dot_plot(points=point_values, lines=label_values)
References
----------
* Cleveland, William S. (1993). "Visualizing Data". Hobart
Press.
* Jacoby, William G. (2006) "The Dot Plot: A Graphical Display
for Labeled Quantitative Values." The Political Methodologist
14(1): 6-14.
"""
import matplotlib.transforms as transforms
fig, ax = utils.create_mpl_ax(ax)
# Convert to numpy arrays if that is not what we are given.
points = np.asarray(points)
if intervals is not None:
intervals = np.asarray(intervals)
if lines is not None:
lines = np.asarray(lines)
if sections is not None:
sections = np.asarray(sections)
if styles is not None:
styles = np.asarray(styles)
# Total number of points
npoint = len(points)
# Set default line values if needed
if lines is None:
lines = np.arange(npoint)
# Set default section values if needed
if sections is None:
sections = np.zeros(npoint)
# Set default style values if needed
if styles is None:
styles = np.zeros(npoint)
# The vertical space (in inches) for a section title
section_title_space = 0.5
# The number of sections
nsect = len(set(sections))
# The number of section titles
nsect_title = nsect if nsect > 1 else 0
# The total vertical space devoted to section titles.
section_space_total = section_title_space * nsect_title
# Add a bit of room so that points that fall at the axis limits
# are not cut in half.
ax.set_xmargin(0.02)
ax.set_ymargin(0.02)
if section_order is None:
lines0 = list(set(sections))
lines0.sort()
else:
lines0 = section_order
if line_order is None:
lines1 = list(set(lines))
lines1.sort()
else:
lines1 = line_order
# A map from (section,line) codes to index positions.
lines_map = {}
for i in range(npoint):
ky = (sections[i], lines[i])
if ky not in lines_map:
lines_map[ky] = []
lines_map[ky].append(i)
# Get the size of the axes on the parent figure in inches
bbox = ax.get_window_extent().transformed(
fig.dpi_scale_trans.inverted())
awidth, aheight = bbox.width, bbox.height
# The number of lines in the plot.
nrows = len(lines_map)
# The positions of the lowest and highest guideline in axes
# coordinates (for horizontal dotplots), or the leftmost and
# rightmost guidelines (for vertical dotplots).
bottom, top = 0, 1
if horizontal:
# x coordinate is data, y coordinate is axes
trans = transforms.blended_transform_factory(ax.transData,
ax.transAxes)
else:
# x coordinate is axes, y coordinate is data
trans = transforms.blended_transform_factory(ax.transAxes,
ax.transData)
# Space used for a section title, in axes coordinates
title_space_axes = section_title_space / aheight
# Space between lines
if horizontal:
dpos = (top - bottom - nsect_title*title_space_axes) /\
float(nrows)
else:
dpos = (top - bottom) / float(nrows)
# Determine the spacing for stacked points
if styles_order is not None:
style_codes = styles_order
else:
style_codes = list(set(styles))
style_codes.sort()
# Order is top to bottom for horizontal plots, so need to
# flip.
if horizontal:
style_codes = style_codes[::-1]
# nval is the maximum number of points on one line.
nval = len(style_codes)
if nval > 1:
stackd = dpos / (2.5*(float(nval)-1))
else:
stackd = 0.
# Map from style code to its integer position
#style_codes_map = {x: style_codes.index(x) for x in style_codes}
# python 2.6 compat version:
style_codes_map = dict((x, style_codes.index(x)) for x in style_codes)
# Setup default marker styles
colors = ["r", "g", "b", "y", "k", "purple", "orange"]
if marker_props is None:
#marker_props = {x: {} for x in style_codes}
# python 2.6 compat version:
marker_props = dict((x, {}) for x in style_codes)
for j in range(nval):
sc = style_codes[j]
if "color" not in marker_props[sc]:
marker_props[sc]["color"] = colors[j % len(colors)]
if "marker" not in marker_props[sc]:
marker_props[sc]["marker"] = "o"
if "ms" not in marker_props[sc]:
marker_props[sc]["ms"] = 10 if stackd == 0 else 6
# Setup default line styles
if line_props is None:
#line_props = {x: {} for x in style_codes}
# python 2.6 compat version:
line_props = dict((x, {}) for x in style_codes)
for j in range(nval):
sc = style_codes[j]
if "color" not in line_props[sc]:
line_props[sc]["color"] = "grey"
if "linewidth" not in line_props[sc]:
line_props[sc]["linewidth"] = 2 if stackd > 0 else 8
if horizontal:
# The vertical position of the first line.
pos = top - dpos/2 if nsect == 1 else top
else:
# The horizontal position of the first line.
pos = bottom + dpos/2
# Points that have already been labeled
labeled = set()
# Positions of the y axis grid lines
ticks = []
# Loop through the sections
for k0 in lines0:
# Draw a section title
if nsect_title > 0:
if horizontal:
y0 = pos + dpos/2 if k0 == lines0[0] else pos
ax.fill_between((0, 1), (y0,y0),
(pos-0.7*title_space_axes,
pos-0.7*title_space_axes),
color='darkgrey',
transform=ax.transAxes,
zorder=1)
txt = ax.text(0.5, pos - 0.35*title_space_axes, k0,
horizontalalignment='center',
verticalalignment='center',
transform=ax.transAxes)
txt.set_fontweight("bold")
pos -= title_space_axes
else:
m = len([k for k in lines_map if k[0] == k0])
ax.fill_between((pos-dpos/2+0.01,
pos+(m-1)*dpos+dpos/2-0.01),
(1.01,1.01), (1.06,1.06),
color='darkgrey',
transform=ax.transAxes,
zorder=1, clip_on=False)
txt = ax.text(pos + (m-1)*dpos/2, 1.02, k0,
horizontalalignment='center',
verticalalignment='bottom',
transform=ax.transAxes)
txt.set_fontweight("bold")
jrow = 0
for k1 in lines1:
# No data to plot
if (k0, k1) not in lines_map:
continue
# Draw the guideline
if horizontal:
ax.axhline(pos, color='grey')
else:
ax.axvline(pos, color='grey')
# Set up the labels
if split_names is not None:
us = k1.split(split_names)
if len(us) >= 2:
left_label, right_label = us[0], us[1]
else:
left_label, right_label = k1, None
else:
left_label, right_label = k1, None
# Draw the stripe
if striped and jrow % 2 == 0:
if horizontal:
ax.fill_between((0, 1), (pos-dpos/2, pos-dpos/2),
(pos+dpos/2, pos+dpos/2),
color='lightgrey',
transform=ax.transAxes,
zorder=0)
else:
ax.fill_between((pos-dpos/2, pos+dpos/2),
(0, 0), (1, 1),
color='lightgrey',
transform=ax.transAxes,
zorder=0)
jrow += 1
# Draw the left margin label
if horizontal:
ax.text(-0.1/awidth, pos, left_label,
horizontalalignment="right",
verticalalignment='center',
transform=ax.transAxes, family='monospace')
else:
ax.text(pos, -0.1/aheight, left_label,
horizontalalignment="center",
verticalalignment='top',
transform=ax.transAxes, family='monospace')
# Draw the right margin label
if right_label is not None:
if horizontal:
ax.text(1 + 0.1/awidth, pos, right_label,
horizontalalignment="left",
verticalalignment='center',
transform=ax.transAxes,
family='monospace')
else:
ax.text(pos, 1 + 0.1/aheight, right_label,
horizontalalignment="center",
verticalalignment='bottom',
transform=ax.transAxes,
family='monospace')
# Save the vertical position so that we can place the
# tick marks
ticks.append(pos)
# Loop over the points in one line
for ji,jp in enumerate(lines_map[(k0,k1)]):
# Calculate the vertical offset
yo = 0
if stacked:
yo = -dpos/5 + style_codes_map[styles[jp]]*stackd
pt = points[jp]
# Plot the interval
if intervals is not None:
# Symmetric interval
if np.isscalar(intervals[jp]):
lcb, ucb = pt - intervals[jp],\
pt + intervals[jp]
# Nonsymmetric interval
else:
lcb, ucb = pt - intervals[jp][0],\
pt + intervals[jp][1]
# Draw the interval
if horizontal:
ax.plot([lcb, ucb], [pos+yo, pos+yo], '-',
transform=trans,
**line_props[styles[jp]])
else:
ax.plot([pos+yo, pos+yo], [lcb, ucb], '-',
transform=trans,
**line_props[styles[jp]])
# Plot the point
sl = styles[jp]
sll = sl if sl not in labeled else None
labeled.add(sl)
if horizontal:
ax.plot([pt,], [pos+yo,], ls='None',
transform=trans, label=sll,
**marker_props[sl])
else:
ax.plot([pos+yo,], [pt,], ls='None',
transform=trans, label=sll,
**marker_props[sl])
if horizontal:
pos -= dpos
else:
pos += dpos
# Set up the axis
if horizontal:
ax.xaxis.set_ticks_position("bottom")
ax.yaxis.set_ticks_position("none")
ax.set_yticklabels([])
ax.spines['left'].set_color('none')
ax.spines['right'].set_color('none')
ax.spines['top'].set_color('none')
ax.spines['bottom'].set_position(('axes', -0.1/aheight))
ax.set_ylim(0, 1)
ax.yaxis.set_ticks(ticks)
ax.autoscale_view(scaley=False, tight=True)
else:
ax.yaxis.set_ticks_position("left")
ax.xaxis.set_ticks_position("none")
ax.set_xticklabels([])
ax.spines['bottom'].set_color('none')
ax.spines['right'].set_color('none')
ax.spines['top'].set_color('none')
ax.spines['left'].set_position(('axes', -0.1/awidth))
ax.set_xlim(0, 1)
ax.xaxis.set_ticks(ticks)
ax.autoscale_view(scalex=False, tight=True)
return fig