matplotlib check_buttons box colors - matplotlib

I am using the check_buttons widget like in the example (http://matplotlib.org/examples/widgets/check_buttons.html)
On a plot with many lines, it is difficult to know from the text which check box goes with which plotted line, at least until the box is clicked and the user looks to see if he can tell which line has disappeared.
Does anyone know if the background color of the check box could be made the same as the line it affects...something like a legend?


You can set the widget box colour as follows,
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.widgets import CheckButtons
t = np.arange(0.0, 2.0, 0.01)
s0 = np.sin(2*np.pi*t)
s1 = np.sin(4*np.pi*t)
s2 = np.sin(6*np.pi*t)
fig, ax = plt.subplots()
l0, = ax.plot(t, s0, visible=False, lw=2)
l1, = ax.plot(t, s1, lw=2)
l2, = ax.plot(t, s2, lw=2)
plt.subplots_adjust(left=0.2)
rax = plt.axes([0.05, 0.4, 0.1, 0.15])
check = CheckButtons(rax, ('2 Hz', '4 Hz', '6 Hz'), (False, True, True))
#Define colours for rectangles and set them
c = ['b', 'g', 'r']
[rec.set_facecolor(c[i]) for i, rec in enumerate(check.rectangles)]
def func(label):
if label == '2 Hz': l0.set_visible(not l0.get_visible())
elif label == '4 Hz': l1.set_visible(not l1.get_visible())
elif label == '6 Hz': l2.set_visible(not l2.get_visible())
plt.draw()
check.on_clicked(func)
plt.show()
The checkbutton panel has each tick box as a matplotlib.patches.Rectangle object which can be customised as needed.

Related

Picker Event to display legend labels in matplotlib

I want the picker event to simply display the legend label when I click on any of the points on my scatter plot. This is what I have and looks like:
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
# x y data and legend labels
x = np.random.uniform(0, 100, 50)
y = np.random.uniform(0, 100, 50)
ID = np.random.randint(0,25,50)
# define the event
def onpick(event):
ind = event.ind
print('x:', x[ind], 'y:', y[ind])
# create the plot
fig, ax = plt.subplots()
scatter = ax.scatter(x, y, c = ID, picker=True)
ax.set_xlabel('x')
ax.set_ylabel('y')
ax.legend(*scatter.legend_elements(num=list(np.unique(ID))),
loc="center left",
title='ID',
bbox_to_anchor=(1, 0.5),
ncol=2
)
ax.ticklabel_format(useOffset=False)
ax.tick_params(axis = 'x',labelrotation = 45)
plt.tight_layout()
# call the event
fig.canvas.mpl_connect('pick_event', onpick)
The scatter plot:
The current output on click:
I want it to print something like:
x: [76.25650514] y: [59.85198124] ID: 11 # the corresponding legend label
I have been searching through the web and couldn't find much I can duplicate from.

Generally, the way you would get the label of the point you clicked on would be print(event.artist.get_label()) but with your custom legends labels, the only thing that prints is _child0. However, due to your custom labels, you can use your variable ID just like how you are using your x and y variables e.g. print('id:', ID[ind]).
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
# x y data and legend labels
x = np.random.uniform(0, 100, 50)
y = np.random.uniform(0, 100, 50)
ID = np.random.randint(0,25,50)
# define the event
def onpick(event):
ind = event.ind
print(event.artist.get_label()) # How you normally get the legend label
print('id:', ID[ind]) # How you can get your custom legend label
print('x:', x[ind], 'y:', y[ind])
# create the plot
fig, ax = plt.subplots()
scatter = ax.scatter(x, y, c = ID, picker=True)
ax.set_xlabel('x')
ax.set_ylabel('y')
ax.legend(*scatter.legend_elements(num=list(np.unique(ID))),
loc="center left",
title='ID',
bbox_to_anchor=(1, 0.5),
ncol=2
)
ax.ticklabel_format(useOffset=False)
ax.tick_params(axis = 'x',labelrotation = 45)
plt.tight_layout()
# call the event
fig.canvas.mpl_connect('pick_event', onpick)
plt.show()
Clicking on the yellow most point gives:
_child0
id: [24]
x: [84.73899472] y: [3.07532246]
Clicking on a very purple point gives:
_child0
id: [2]
x: [99.88397652] y: [98.89144833]

How to show ranges of values with a color assigned in the legend?

With this code i'm creating colorbar scales with the function make_colormap. Source:Create own colormap using matplotlib and plot color scale
import matplotlib.colors as mcolors
def make_colormap(seq):
"""Return a LinearSegmentedColormap
seq: a sequence of floats and RGB-tuples. The floats should be increasing
and in the interval (0,1).
"""
seq = [(None,) * 3, 0.0] + list(seq) + [1.0, (None,) * 3]
cdict = {'red': [], 'green': [], 'blue': []}
for i, item in enumerate(seq):
if isinstance(item, float):
r1, g1, b1 = seq[i - 1]
r2, g2, b2 = seq[i + 1]
cdict['red'].append([item, r1, r2])
cdict['green'].append([item, g1, g2])
cdict['blue'].append([item, b1, b2])
return mcolors.LinearSegmentedColormap('CustomMap', cdict)
c = mcolors.ColorConverter().to_rgb
rvb = make_colormap([c('grey'), c('grey'), norm(3), c('sandybrown'), c('sandybrown'),
norm(5), c('yellow'), c('yellow'), norm(10), c('navajowhite'),
c('navajowhite'), norm(15),c('lightgreen'), c('lightgreen'),norm(20),c('lime'), c('lime'),
norm(50),c('limegreen'), c('limegreen'),norm(80),c('forestgreen'), c('forestgreen'),norm(120),
c('green'), c('green'),norm(160),c('darkgreen'), c('darkgreen'),norm(200),c('teal'), c('teal'),norm(300),
c('mediumaquamarine'), c('mediumaquamarine'),norm(500),c('lightseagreen'), c('lightseagreen'),norm(700),
c('lightskyblue'), c('lightskyblue')])
So in variable rvb i'm asssing a color to ranges of values. How can i assing a color to an specific ranges of values? For example: Grey to 0-3, sandybrown to 4-5, yellow to 6-10, etc.
The map is this:
Also i want to the legend show those values assigned. For example Grey color 0-3, sandybrown 4-5, etc.
Something similar to this image (no need to be equal to the image, just need to show ranges with colors):
I also will show you part of my code when i create the map:
fig = plt.figure('map', figsize=(7,7), dpi=200)
ax = fig.add_axes([0.1, 0.12, 0.80, 0.75], projection=ccrs.PlateCarree())
plt.title('xxx')
plt.xlabel('LONGITUD')
plt.ylabel('LATITUD')
ax.outline_patch.set_linewidth(0.3)
l = NaturalEarthFeature(category='cultural', name='admin_0_countries', scale='50m', facecolor='none')
ax.add_feature(l, edgecolor='black', linewidth=0.25)
img = ax.scatter(lons, lats, s=7, c=ppvalues, cmap=rvb,norm=norm,
marker='o', transform=ccrs.PlateCarree())
handles, labels = img.legend_elements(alpha=0.2)
plt.legend(handles, labels,prop={'weight':'bold','size':10}, title='Meteorological\nStations',title_fontsize=9, scatterpoints=2);
cb = plt.colorbar(img, extend='both',
spacing='proportional', orientation='horizontal',
cax=fig.add_axes([0.12, 0.12, 0.76, 0.02]))
ax.set_extent([-90.0, -60.0, -20.0, 0.0], crs=ccrs.PlateCarree())

I don't understand the function in the question, but I have coded how to create a legend with a specified color, specified label, and specified ticks, and how to give a color bar a specified tick. Please correct the addition of colors and the tick spacing in the color bar.
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
from matplotlib.colors import LinearSegmentedColormap
list_color = ['grey','sandybrown','sandybrown','yellow',
'navajowhite','lightgreen','lime','limegreen',
'forestgreen','green','darkgreen','teal',
'mediumaquamarine','lightseagreen','lightskyblue']
list_label = ['0-3', '4-5', '6-10', '11-15',
'16-20', '21-50', '51-80', '81-120',
'121-160', '161-200','201-300','301-500',
'501-700','701-900','901-1200']
list_ticks = np.linspace(0, 1, 15)
vmin,vmax = 0, 1
cm = LinearSegmentedColormap.from_list('custom_cmap', list_color, N=len(list_color))
plt.imshow(np.linspace(0, 1, 25).reshape(5,5), cmap=cm, interpolation='nearest', vmin=vmin, vmax=vmax)
cbar = plt.colorbar( orientation='horizontal', extend='neither', ticks=list_ticks)
cbar.ax.set_xticklabels(list_label, rotation=45, fontsize=14)
all_patches = []
for h,l in zip(list_color, list_label):
patch = mpatches.Patch(color=h, label=l)
all_patches.append(patch)
plt.legend(handles=all_patches, loc='upper right', ncol=3, bbox_to_anchor=(3, 1))
plt.show()

Condition callback function in matplotlib

I created a bar chart using the following code :
%matplotlib notebook
import matplotlib.pyplot as plt
import matplotlib.animation as animation
import pandas as pd
import numpy as np
import scipy.stats
from matplotlib.widgets import Slider, Button, RadioButtons
np.random.seed(12345)
df = pd.DataFrame([np.random.normal(32000,200000,3650),
np.random.normal(43000,100000,3650),
np.random.normal(43500,140000,3650),
np.random.normal(48000,70000,3650)],
index=[1992,1993,1994,1995])
x = df.T.agg(lambda z : z.mean())
def mean_IC(data, confidence=0.95):
n = len(data)
m, se = data.mean(), scipy.stats.sem(data)
h = se * scipy.stats.t.ppf((1 + confidence) / 2., n-1)
return m, m-h, m+h
plt.subplots_adjust(right=0.8)
yerr1 = np.array([[mean_IC(df.iloc[i])[0] - mean_IC(df.iloc[i])[1] for i in range(len(x.index))],
[mean_IC(df.iloc[i])[2] - mean_IC(df.iloc[i])[0] for i in range(len(x.index))]])
ax = plt.bar(range(len(x.index)), x, align='center', yerr=yerr1, width=1, edgecolor='black')
_=plt.xticks(range(len(x.index)), x.index)
#plt.bar(x.index.astype(str), x, align='center')
ax = plt.gca()
def step1(event):
plt.sca(ax)
plt.cla()
plt.bar(range(len(x.index)), x, align='center', yerr=yerr1, width=1, edgecolor='black')
plt.xticks(range(len(x.index)), x.index)
plt.axhline(y=event.ydata, color='black', linestyle='--', linewidth=1)
# tell mpl_connect we want to pass a 'button_press_event' into step1 when the event is detected
plt.gcf().canvas.mpl_connect('button_press_event', step1)
def step2(event) :
axcolor = 'lightgoldenrodyellow'
plt.axes([0.83, 0.7, 0.15, 0.25], facecolor=axcolor)
ax1 = plt.gca()
ax1.cla()
plt.axes([0.83, 0.7, 0.15, 0.25], facecolor=axcolor)
plt.gca().get_xaxis().set_visible(False)
plt.gca().get_yaxis().set_visible(False)
plt.text(0.5, 0.5,'Currently\nchoosing\n y=\n{:.4f}'.format(event.ydata), family='serif', ha='center', wrap=True)
button_ax = plt.axes([0.855, 0.73, 0.1, 0.055])
button = Button(button_ax, 'Continue', color='grey')
plt.gcf().canvas.mpl_connect('button_press_event', step2)
What I'm trying to do is to draw a horizontal line in the bar chart depending on where the user clicks, and then have the y value printed in the new axes object that I added. The problem is I want this to happen only when the user clicks in the actual figure of the bar chart. Instead, what happens is that when you click outside the figure or in the axes object on the right, it also takes into account this as an event. So how can I make the callback function only work under a condition ? I tried many things but nothing seems to work ..

jupyter notebook matplotlib show plot and then plot on the origin figure

I want to plot a white plot with two axes, show it to the user, then add a line to the white plot with two axes, show it to the user, then add some dot to the line, then show it to the user. How can I do this without copying the code again and again?
What I'm doing now is in the first code chunk
import math
import matplotlib.pyplot as plt
import numpy as np
%matplotlib inline
fig = plt.figure(figsize=(5,5))
ax = plt.axes()
ax.set_xlabel('cat')
ax.set_ylabel('dog')
plt.title("Set of 2 animals")
plt.show()
then in the second code chunk
fig = plt.figure(figsize=(5,5))
ax = plt.axes()
x = np.linspace(0, 1.0, 1000)
ax.plot(x, 1.0-x,zorder = 0)
ax.set_xlabel('cat')
ax.set_ylabel('dog')
plt.title("Set of 2 animals")
plt.show()
then in the third code chunk
fig = plt.figure(figsize=(5,5))
ax = plt.axes()
x = np.linspace(0, 1.0, 1000)
ax.plot(x, 1.0-x,zorder = 0)
ax.set_xlabel('cat')
ax.set_ylabel('dog')
plt.title("Set of 2 animals")
p0 = 0.5
p1 = 0.5
color = "blue"
textd =0.05
ax.scatter([p0],[p1], color = color,zorder=1)
ax.text(p0+textd, p1+textd, 'tiger',color = color,zorder =2)
plt.show()
What I'm looking for is things like in the first code chunk
import math
import matplotlib.pyplot as plt
import numpy as np
%matplotlib inline
fig = plt.figure(figsize=(5,5))
ax = plt.axes()
ax.set_xlabel('cat')
ax.set_ylabel('dog')
plt.title("Set of 2 animals")
plt.show()
then in the second code chunk
add line directly without duplicating the code for making axes
plt.show()
then in the third code chunk
add point directly without duplicating the code for making axes and lines
plt.show()

Update: I actually figured out the answer.
def plot(step):
fig = plt.figure(figsize=(5,5))
ax = plt.axes()
ax.set_xlabel('cat')
ax.set_ylabel('dog')
plt.title("Set of 2 animals")
if step>=1:
x = np.linspace(0, 1.0, 1000)
ax.plot(x, 1.0-x,zorder = 0)
if step>=2:
p0 = 0.5
p1 = 0.5
color = "blue"
textd =0.05
ax.scatter([p0],[p1], color = color,zorder=1)
ax.text(p0+textd, p1+textd, 'tiger',color = color,zorder =2)
plot.show()
should be able to solve the problem.

Matplotlib - How to show coordinates in scatterplot? [duplicate]

I am using matplotlib to make scatter plots. Each point on the scatter plot is associated with a named object. I would like to be able to see the name of an object when I hover my cursor over the point on the scatter plot associated with that object. In particular, it would be nice to be able to quickly see the names of the points that are outliers. The closest thing I have been able to find while searching here is the annotate command, but that appears to create a fixed label on the plot. Unfortunately, with the number of points that I have, the scatter plot would be unreadable if I labeled each point. Does anyone know of a way to create labels that only appear when the cursor hovers in the vicinity of that point?

It seems none of the other answers here actually answer the question. So here is a code that uses a scatter and shows an annotation upon hovering over the scatter points.
import matplotlib.pyplot as plt
import numpy as np; np.random.seed(1)
x = np.random.rand(15)
y = np.random.rand(15)
names = np.array(list("ABCDEFGHIJKLMNO"))
c = np.random.randint(1,5,size=15)
norm = plt.Normalize(1,4)
cmap = plt.cm.RdYlGn
fig,ax = plt.subplots()
sc = plt.scatter(x,y,c=c, s=100, cmap=cmap, norm=norm)
annot = ax.annotate("", xy=(0,0), xytext=(20,20),textcoords="offset points",
bbox=dict(boxstyle="round", fc="w"),
arrowprops=dict(arrowstyle="->"))
annot.set_visible(False)
def update_annot(ind):
pos = sc.get_offsets()[ind["ind"][0]]
annot.xy = pos
text = "{}, {}".format(" ".join(list(map(str,ind["ind"]))),
" ".join([names[n] for n in ind["ind"]]))
annot.set_text(text)
annot.get_bbox_patch().set_facecolor(cmap(norm(c[ind["ind"][0]])))
annot.get_bbox_patch().set_alpha(0.4)
def hover(event):
vis = annot.get_visible()
if event.inaxes == ax:
cont, ind = sc.contains(event)
if cont:
update_annot(ind)
annot.set_visible(True)
fig.canvas.draw_idle()
else:
if vis:
annot.set_visible(False)
fig.canvas.draw_idle()
fig.canvas.mpl_connect("motion_notify_event", hover)
plt.show()
Because people also want to use this solution for a line plot instead of a scatter, the following would be the same solution for plot (which works slightly differently).
import matplotlib.pyplot as plt
import numpy as np; np.random.seed(1)
x = np.sort(np.random.rand(15))
y = np.sort(np.random.rand(15))
names = np.array(list("ABCDEFGHIJKLMNO"))
norm = plt.Normalize(1,4)
cmap = plt.cm.RdYlGn
fig,ax = plt.subplots()
line, = plt.plot(x,y, marker="o")
annot = ax.annotate("", xy=(0,0), xytext=(-20,20),textcoords="offset points",
bbox=dict(boxstyle="round", fc="w"),
arrowprops=dict(arrowstyle="->"))
annot.set_visible(False)
def update_annot(ind):
x,y = line.get_data()
annot.xy = (x[ind["ind"][0]], y[ind["ind"][0]])
text = "{}, {}".format(" ".join(list(map(str,ind["ind"]))),
" ".join([names[n] for n in ind["ind"]]))
annot.set_text(text)
annot.get_bbox_patch().set_alpha(0.4)
def hover(event):
vis = annot.get_visible()
if event.inaxes == ax:
cont, ind = line.contains(event)
if cont:
update_annot(ind)
annot.set_visible(True)
fig.canvas.draw_idle()
else:
if vis:
annot.set_visible(False)
fig.canvas.draw_idle()
fig.canvas.mpl_connect("motion_notify_event", hover)
plt.show()
In case someone is looking for a solution for lines in twin axes, refer to How to make labels appear when hovering over a point in multiple axis?
In case someone is looking for a solution for bar plots, please refer to e.g. this answer.

This solution works when hovering a line without the need to click it:
import matplotlib.pyplot as plt
# Need to create as global variable so our callback(on_plot_hover) can access
fig = plt.figure()
plot = fig.add_subplot(111)
# create some curves
for i in range(4):
# Giving unique ids to each data member
plot.plot(
[i*1,i*2,i*3,i*4],
gid=i)
def on_plot_hover(event):
# Iterating over each data member plotted
for curve in plot.get_lines():
# Searching which data member corresponds to current mouse position
if curve.contains(event)[0]:
print("over %s" % curve.get_gid())
fig.canvas.mpl_connect('motion_notify_event', on_plot_hover)
plt.show()

From http://matplotlib.sourceforge.net/examples/event_handling/pick_event_demo.html :
from matplotlib.pyplot import figure, show
import numpy as npy
from numpy.random import rand
if 1: # picking on a scatter plot (matplotlib.collections.RegularPolyCollection)
x, y, c, s = rand(4, 100)
def onpick3(event):
ind = event.ind
print('onpick3 scatter:', ind, npy.take(x, ind), npy.take(y, ind))
fig = figure()
ax1 = fig.add_subplot(111)
col = ax1.scatter(x, y, 100*s, c, picker=True)
#fig.savefig('pscoll.eps')
fig.canvas.mpl_connect('pick_event', onpick3)
show()
This recipe draws an annotation on picking a data point: http://scipy-cookbook.readthedocs.io/items/Matplotlib_Interactive_Plotting.html .
This recipe draws a tooltip, but it requires wxPython:
Point and line tooltips in matplotlib?

The easiest option is to use the mplcursors package.
mplcursors: read the docs
mplcursors: github
If using Anaconda, install with these instructions, otherwise use these instructions for pip.
This must be plotted in an interactive window, not inline.
For jupyter, executing something like %matplotlib qt in a cell will turn on interactive plotting. See How can I open the interactive matplotlib window in IPython notebook?
Tested in python 3.10, pandas 1.4.2, matplotlib 3.5.1, seaborn 0.11.2
import matplotlib.pyplot as plt
import pandas_datareader as web # only for test data; must be installed with conda or pip
from mplcursors import cursor # separate package must be installed
# reproducible sample data as a pandas dataframe
df = web.DataReader('aapl', data_source='yahoo', start='2021-03-09', end='2022-06-13')
plt.figure(figsize=(12, 7))
plt.plot(df.index, df.Close)
cursor(hover=True)
plt.show()
Pandas
ax = df.plot(y='Close', figsize=(10, 7))
cursor(hover=True)
plt.show()
Seaborn
Works with axes-level plots like sns.lineplot, and figure-level plots like sns.relplot.
import seaborn as sns
# load sample data
tips = sns.load_dataset('tips')
sns.relplot(data=tips, x="total_bill", y="tip", hue="day", col="time")
cursor(hover=True)
plt.show()

The other answers did not address my need for properly showing tooltips in a recent version of Jupyter inline matplotlib figure. This one works though:
import matplotlib.pyplot as plt
import numpy as np
import mplcursors
np.random.seed(42)
fig, ax = plt.subplots()
ax.scatter(*np.random.random((2, 26)))
ax.set_title("Mouse over a point")
crs = mplcursors.cursor(ax,hover=True)
crs.connect("add", lambda sel: sel.annotation.set_text(
'Point {},{}'.format(sel.target[0], sel.target[1])))
plt.show()
Leading to something like the following picture when going over a point with mouse:

A slight edit on an example provided in http://matplotlib.org/users/shell.html:
import numpy as np
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(111)
ax.set_title('click on points')
line, = ax.plot(np.random.rand(100), '-', picker=5) # 5 points tolerance
def onpick(event):
thisline = event.artist
xdata = thisline.get_xdata()
ydata = thisline.get_ydata()
ind = event.ind
print('onpick points:', *zip(xdata[ind], ydata[ind]))
fig.canvas.mpl_connect('pick_event', onpick)
plt.show()
This plots a straight line plot, as Sohaib was asking

mpld3 solve it for me.
EDIT (CODE ADDED):
import matplotlib.pyplot as plt
import numpy as np
import mpld3
fig, ax = plt.subplots(subplot_kw=dict(axisbg='#EEEEEE'))
N = 100
scatter = ax.scatter(np.random.normal(size=N),
np.random.normal(size=N),
c=np.random.random(size=N),
s=1000 * np.random.random(size=N),
alpha=0.3,
cmap=plt.cm.jet)
ax.grid(color='white', linestyle='solid')
ax.set_title("Scatter Plot (with tooltips!)", size=20)
labels = ['point {0}'.format(i + 1) for i in range(N)]
tooltip = mpld3.plugins.PointLabelTooltip(scatter, labels=labels)
mpld3.plugins.connect(fig, tooltip)
mpld3.show()
You can check this example

mplcursors worked for me. mplcursors provides clickable annotation for matplotlib. It is heavily inspired from mpldatacursor (https://github.com/joferkington/mpldatacursor), with a much simplified API
import matplotlib.pyplot as plt
import numpy as np
import mplcursors
data = np.outer(range(10), range(1, 5))
fig, ax = plt.subplots()
lines = ax.plot(data)
ax.set_title("Click somewhere on a line.\nRight-click to deselect.\n"
"Annotations can be dragged.")
mplcursors.cursor(lines) # or just mplcursors.cursor()
plt.show()

showing object information in matplotlib statusbar
Features
no extra libraries needed
clean plot
no overlap of labels and artists
supports multi artist labeling
can handle artists from different plotting calls (like scatter, plot, add_patch)
code in library style
Code
### imports
import matplotlib as mpl
import matplotlib.pylab as plt
import numpy as np
# https://stackoverflow.com/a/47166787/7128154
# https://matplotlib.org/3.3.3/api/collections_api.html#matplotlib.collections.PathCollection
# https://matplotlib.org/3.3.3/api/path_api.html#matplotlib.path.Path
# https://stackoverflow.com/questions/15876011/add-information-to-matplotlib-navigation-toolbar-status-bar
# https://stackoverflow.com/questions/36730261/matplotlib-path-contains-point
# https://stackoverflow.com/a/36335048/7128154
class StatusbarHoverManager:
"""
Manage hover information for mpl.axes.Axes object based on appearing
artists.
Attributes
----------
ax : mpl.axes.Axes
subplot to show status information
artists : list of mpl.artist.Artist
elements on the subplot, which react to mouse over
labels : list (list of strings) or strings
each element on the top level corresponds to an artist.
if the artist has items
(i.e. second return value of contains() has key 'ind'),
the element has to be of type list.
otherwise the element if of type string
cid : to reconnect motion_notify_event
"""
def __init__(self, ax):
assert isinstance(ax, mpl.axes.Axes)
def hover(event):
if event.inaxes != ax:
return
info = 'x={:.2f}, y={:.2f}'.format(event.xdata, event.ydata)
ax.format_coord = lambda x, y: info
cid = ax.figure.canvas.mpl_connect("motion_notify_event", hover)
self.ax = ax
self.cid = cid
self.artists = []
self.labels = []
def add_artist_labels(self, artist, label):
if isinstance(artist, list):
assert len(artist) == 1
artist = artist[0]
self.artists += [artist]
self.labels += [label]
def hover(event):
if event.inaxes != self.ax:
return
info = 'x={:.2f}, y={:.2f}'.format(event.xdata, event.ydata)
for aa, artist in enumerate(self.artists):
cont, dct = artist.contains(event)
if not cont:
continue
inds = dct.get('ind')
if inds is not None: # artist contains items
for ii in inds:
lbl = self.labels[aa][ii]
info += '; artist [{:d}, {:d}]: {:}'.format(
aa, ii, lbl)
else:
lbl = self.labels[aa]
info += '; artist [{:d}]: {:}'.format(aa, lbl)
self.ax.format_coord = lambda x, y: info
self.ax.figure.canvas.mpl_disconnect(self.cid)
self.cid = self.ax.figure.canvas.mpl_connect(
"motion_notify_event", hover)
def demo_StatusbarHoverManager():
fig, ax = plt.subplots()
shm = StatusbarHoverManager(ax)
poly = mpl.patches.Polygon(
[[0,0], [3, 5], [5, 4], [6,1]], closed=True, color='green', zorder=0)
artist = ax.add_patch(poly)
shm.add_artist_labels(artist, 'polygon')
artist = ax.scatter([2.5, 1, 2, 3], [6, 1, 1, 7], c='blue', s=10**2)
lbls = ['point ' + str(ii) for ii in range(4)]
shm.add_artist_labels(artist, lbls)
artist = ax.plot(
[0, 0, 1, 5, 3], [0, 1, 1, 0, 2], marker='o', color='red')
lbls = ['segment ' + str(ii) for ii in range(5)]
shm.add_artist_labels(artist, lbls)
plt.show()
# --- main
if __name__== "__main__":
demo_StatusbarHoverManager()

I have made a multi-line annotation system to add to: https://stackoverflow.com/a/47166787/10302020.
for the most up to date version:
https://github.com/AidenBurgess/MultiAnnotationLineGraph
Simply change the data in the bottom section.
import matplotlib.pyplot as plt
def update_annot(ind, line, annot, ydata):
x, y = line.get_data()
annot.xy = (x[ind["ind"][0]], y[ind["ind"][0]])
# Get x and y values, then format them to be displayed
x_values = " ".join(list(map(str, ind["ind"])))
y_values = " ".join(str(ydata[n]) for n in ind["ind"])
text = "{}, {}".format(x_values, y_values)
annot.set_text(text)
annot.get_bbox_patch().set_alpha(0.4)
def hover(event, line_info):
line, annot, ydata = line_info
vis = annot.get_visible()
if event.inaxes == ax:
# Draw annotations if cursor in right position
cont, ind = line.contains(event)
if cont:
update_annot(ind, line, annot, ydata)
annot.set_visible(True)
fig.canvas.draw_idle()
else:
# Don't draw annotations
if vis:
annot.set_visible(False)
fig.canvas.draw_idle()
def plot_line(x, y):
line, = plt.plot(x, y, marker="o")
# Annotation style may be changed here
annot = ax.annotate("", xy=(0, 0), xytext=(-20, 20), textcoords="offset points",
bbox=dict(boxstyle="round", fc="w"),
arrowprops=dict(arrowstyle="->"))
annot.set_visible(False)
line_info = [line, annot, y]
fig.canvas.mpl_connect("motion_notify_event",
lambda event: hover(event, line_info))
# Your data values to plot
x1 = range(21)
y1 = range(0, 21)
x2 = range(21)
y2 = range(0, 42, 2)
# Plot line graphs
fig, ax = plt.subplots()
plot_line(x1, y1)
plot_line(x2, y2)
plt.show()

Based off Markus Dutschke" and "ImportanceOfBeingErnest", I (imo) simplified the code and made it more modular.
Also this doesn't require additional packages to be installed.
import matplotlib.pylab as plt
import numpy as np
plt.close('all')
fh, ax = plt.subplots()
#Generate some data
y,x = np.histogram(np.random.randn(10000), bins=500)
x = x[:-1]
colors = ['#0000ff', '#00ff00','#ff0000']
x2, y2 = x,y/10
x3, y3 = x, np.random.randn(500)*10+40
#Plot
h1 = ax.plot(x, y, color=colors[0])
h2 = ax.plot(x2, y2, color=colors[1])
h3 = ax.scatter(x3, y3, color=colors[2], s=1)
artists = h1 + h2 + [h3] #concatenating lists
labels = [list('ABCDE'*100),list('FGHIJ'*100),list('klmno'*100)] #define labels shown
#___ Initialize annotation arrow
annot = ax.annotate("", xy=(0,0), xytext=(20,20),textcoords="offset points",
bbox=dict(boxstyle="round", fc="w"),
arrowprops=dict(arrowstyle="->"))
annot.set_visible(False)
def on_plot_hover(event):
if event.inaxes != ax: #exit if mouse is not on figure
return
is_vis = annot.get_visible() #check if an annotation is visible
# x,y = event.xdata,event.ydata #coordinates of mouse in graph
for ii, artist in enumerate(artists):
is_contained, dct = artist.contains(event)
if(is_contained):
if('get_data' in dir(artist)): #for plot
data = list(zip(*artist.get_data()))
elif('get_offsets' in dir(artist)): #for scatter
data = artist.get_offsets().data
inds = dct['ind'] #get which data-index is under the mouse
#___ Set Annotation settings
xy = data[inds[0]] #get 1st position only
annot.xy = xy
annot.set_text(f'pos={xy},text={labels[ii][inds[0]]}')
annot.get_bbox_patch().set_edgecolor(colors[ii])
annot.get_bbox_patch().set_alpha(0.7)
annot.set_visible(True)
fh.canvas.draw_idle()
else:
if is_vis:
annot.set_visible(False) #disable when not hovering
fh.canvas.draw_idle()
fh.canvas.mpl_connect('motion_notify_event', on_plot_hover)
Giving the following result:

Maybe this helps anybody, but I have adapted the #ImportanceOfBeingErnest's answer to work with patches and classes. Features:
The entire framework is contained inside of a single class, so all of the used variables are only available within their relevant scopes.
Can create multiple distinct sets of patches
Hovering over a patch prints patch collection name and patch subname
Hovering over a patch highlights all patches of that collection by changing their edge color to black
Note: For my applications, the overlap is not relevant, thus only one object's name is displayed at a time. Feel free to extend to multiple objects if you wish, it is not too hard.
Usage
fig, ax = plt.subplots(tight_layout=True)
ap = annotated_patches(fig, ax)
ap.add_patches('Azure', 'circle', 'blue', np.random.uniform(0, 1, (4,2)), 'ABCD', 0.1)
ap.add_patches('Lava', 'rect', 'red', np.random.uniform(0, 1, (3,2)), 'EFG', 0.1, 0.05)
ap.add_patches('Emerald', 'rect', 'green', np.random.uniform(0, 1, (3,2)), 'HIJ', 0.05, 0.1)
plt.axis('equal')
plt.axis('off')
plt.show()
Implementation
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
from matplotlib.collections import PatchCollection
np.random.seed(1)
class annotated_patches:
def __init__(self, fig, ax):
self.fig = fig
self.ax = ax
self.annot = self.ax.annotate("", xy=(0,0),
xytext=(20,20),
textcoords="offset points",
bbox=dict(boxstyle="round", fc="w"),
arrowprops=dict(arrowstyle="->"))
self.annot.set_visible(False)
self.collectionsDict = {}
self.coordsDict = {}
self.namesDict = {}
self.isActiveDict = {}
self.motionCallbackID = self.fig.canvas.mpl_connect("motion_notify_event", self.hover)
def add_patches(self, groupName, kind, color, xyCoords, names, *params):
if kind=='circle':
circles = [mpatches.Circle(xy, *params, ec="none") for xy in xyCoords]
thisCollection = PatchCollection(circles, facecolor=color, alpha=0.5, edgecolor=None)
ax.add_collection(thisCollection)
elif kind == 'rect':
rectangles = [mpatches.Rectangle(xy, *params, ec="none") for xy in xyCoords]
thisCollection = PatchCollection(rectangles, facecolor=color, alpha=0.5, edgecolor=None)
ax.add_collection(thisCollection)
else:
raise ValueError('Unexpected kind', kind)
self.collectionsDict[groupName] = thisCollection
self.coordsDict[groupName] = xyCoords
self.namesDict[groupName] = names
self.isActiveDict[groupName] = False
def update_annot(self, groupName, patchIdxs):
self.annot.xy = self.coordsDict[groupName][patchIdxs[0]]
self.annot.set_text(groupName + ': ' + self.namesDict[groupName][patchIdxs[0]])
# Set edge color
self.collectionsDict[groupName].set_edgecolor('black')
self.isActiveDict[groupName] = True
def hover(self, event):
vis = self.annot.get_visible()
updatedAny = False
if event.inaxes == self.ax:
for groupName, collection in self.collectionsDict.items():
cont, ind = collection.contains(event)
if cont:
self.update_annot(groupName, ind["ind"])
self.annot.set_visible(True)
self.fig.canvas.draw_idle()
updatedAny = True
else:
if self.isActiveDict[groupName]:
collection.set_edgecolor(None)
self.isActiveDict[groupName] = True
if (not updatedAny) and vis:
self.annot.set_visible(False)
self.fig.canvas.draw_idle()