Question

我有一个二维散点图，对应于图像。当你将鼠标悬停在每个点上时，我想知道是否有一种简单的方法来显示相应的图像（作为弹出窗口或工具提示）？我尝试了一下，但发现你需要手动编辑javascript才能让悬停事件发挥作用。是否只有matplotlib或其他常见软件包有一个简单的解决方案？

Answer 1

在此处找到有关如何在悬停事件中显示图像的完整解决方案。它使用'motion_notify_event'来检测鼠标何时在散点（悬停）上。如果是这种情况，它会显示image annotation，并在悬停的散点旁边显示相应的图像。

import matplotlib.pyplot as plt
from matplotlib.offsetbox import OffsetImage, AnnotationBbox
import numpy as np; np.random.seed(42)

# Generate data x, y for scatter and an array of images.
x = np.arange(20)
y = np.random.rand(len(x))
arr = np.empty((len(x),10,10))
for i in range(len(x)):
    f = np.random.rand(5,5)
    arr[i, 0:5,0:5] = f
    arr[i, 5:,0:5] =np.flipud(f)
    arr[i, 5:,5:] =np.fliplr(np.flipud(f))
    arr[i, 0:5:,5:] = np.fliplr(f)

# create figure and plot scatter
fig = plt.figure()
ax = fig.add_subplot(111)
line, = ax.plot(x,y, ls="", marker="o")

# create the annotations box
im = OffsetImage(arr[0,:,:], zoom=5)
xybox=(50., 50.)
ab = AnnotationBbox(im, (0,0), xybox=xybox, xycoords='data',
        boxcoords="offset points",  pad=0.3,  arrowprops=dict(arrowstyle="->"))
# add it to the axes and make it invisible
ax.add_artist(ab)
ab.set_visible(False)

def hover(event):
    # if the mouse is over the scatter points
    if line.contains(event)[0]:
        # find out the index within the array from the event
        ind, = line.contains(event)[1]["ind"]
        # get the figure size
        w,h = fig.get_size_inches()*fig.dpi
        ws = (event.x > w/2.)*-1 + (event.x <= w/2.) 
        hs = (event.y > h/2.)*-1 + (event.y <= h/2.)
        # if event occurs in the top or right quadrant of the figure,
        # change the annotation box position relative to mouse.
        ab.xybox = (xybox[0]*ws, xybox[1]*hs)
        # make annotation box visible
        ab.set_visible(True)
        # place it at the position of the hovered scatter point
        ab.xy =(x[ind], y[ind])
        # set the image corresponding to that point
        im.set_data(arr[ind,:,:])
    else:
        #if the mouse is not over a scatter point
        ab.set_visible(False)
    fig.canvas.draw_idle()

# add callback for mouse moves
fig.canvas.mpl_connect('motion_notify_event', hover)           
plt.show()

Answer 2

如果要以RGB显示图像，则必须稍微调整代码。对于此示例，映像需要位于磁盘上。不用在第一个维度仅表示索引的图像上使用3darray，而是需要使用plt.imread读取图像，然后将set_data设置到包含图像名称的数组中的相应位置。

import matplotlib.pyplot as plt
from matplotlib.offsetbox import OffsetImage, AnnotationBbox
import numpy as np; np.random.seed(42)
import os

os.chdir('Path/to/your/images')

# Generate data x, y for scatter and an array of images.
x = np.arange(3)
y = np.random.rand(len(x))
jpg_name_np = np.array(['904646.jpg', '903825.jpg', '905722.jpg']).astype('<U12') # names of your images files

cmap = plt.cm.RdYlGn

# create figure and plot scatter
fig = plt.figure()
ax = fig.add_subplot(111)
#line, = ax.plot(x,y, ls="", marker="o")
line = plt.scatter(x,y,c=heat, s=10, cmap=cmap)
image_path = np.asarray(jpg_name_np)

# create the annotations box
image = plt.imread(image_path[0])
im = OffsetImage(image, zoom=0.1)
xybox=(50., 50.)
ab = AnnotationBbox(im, (0,0), xybox=xybox, xycoords='data',
        boxcoords="offset points",  pad=0.3,  arrowprops=dict(arrowstyle="->"))
# add it to the axes and make it invisible
ax.add_artist(ab)
ab.set_visible(False)

def hover(event):
    # if the mouse is over the scatter points
    if line.contains(event)[0]:
        # find out the index within the array from the event
        ind, = line.contains(event)[1]["ind"]
        # get the figure size
        w,h = fig.get_size_inches()*fig.dpi
        ws = (event.x > w/2.)*-1 + (event.x <= w/2.) 
        hs = (event.y > h/2.)*-1 + (event.y <= h/2.)
        # if event occurs in the top or right quadrant of the figure,
        # change the annotation box position relative to mouse.
        ab.xybox = (xybox[0]*ws, xybox[1]*hs)
        # make annotation box visible
        ab.set_visible(True)
        # place it at the position of the hovered scatter point
        ab.xy =(x[ind], y[ind])
        # set the image corresponding to that point
        im.set_data(plt.imread(image_path[ind]))
    else:
        #if the mouse is not over a scatter point
        ab.set_visible(False)
    fig.canvas.draw_idle()

# add callback for mouse moves
fig.canvas.mpl_connect('motion_notify_event', hover)  

fig = plt.gcf()
fig.set_size_inches(10.5, 9.5)

plt.show()

Plot when hovering over scatterpoint

Python在鼠标悬停在一个点上时显示图像

2 个答案: