如何通过将光标悬停在热图元素上来显示它的值？

Question

当我将鼠标悬停在热图上时，我想显示热图中特定元素的值。

我让它显示热图的值，但它显示的信息我也不想要，当我第一次运行程序时，有很多错误，我不知道为什么。

我尝试过各种方法来显示我在网上看到的价值，比如datacursor(hover=True)，但是mplcursors.cursor(hover=True)是唯一一个“有效”的方法。

import tkinter as tk                                                    
from tkinter import ttk
from tkinter import messagebox
import numpy as np
from math import pi
import random
import matplotlib.pyplot as plt

from mpldatacursor import datacursor
import mplcursors

from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg


import pandas as pd
from openpyxl import load_workbook
from tkinter import filedialog

root = tk.Tk()                                                          
root.title("Stage 2 GUI")                                               
root.geometry("1270x590")  

mapArr = np.zeros([2,2],dtype=float)

mapArr=([113,62,31,63],
        [50,101,72,47],
        [92,10,40,12],
        [83,21,128,16])

xy=(['A','B','C','D','E','F'])


figure, axis = plt.subplots(figsize=(8,7))                              
heatmap = axis.imshow(
    mapArr,cmap="gray",interpolation='nearest',vmin=0, vmax=128)        

heatmap.axes.get_xaxis().set_visible(False)                             
heatmap.axes.get_yaxis().set_visible(False)

cb = figure.colorbar(heatmap)                                           

canvas = FigureCanvasTkAgg(figure, root)                                
canvas.get_tk_widget().place(x=-60,y=-60)                               

mplcursors.cursor(hover=True)

plt.show()

我想显示heatmap元素的值，但不显示x和y坐标，但我不知道如何删除/自定义显示的信息，如果每当我运行程序时没有错误(即使它在技术上确实有效)，我也希望这样做。

Answer 1

您需要决定是否要在tk中使用pyplot或。下面假设您希望嵌入(在这种情况下，不要使用pyplot!!)。

使用mplcur标

mplcursors文档解释了如何自定义输出。本质上，它由连接到一个名为"add"的事件组成。

import numpy as np
import matplotlib
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
import tkinter as tk
import mplcursors

root = tk.Tk()
root.geometry("1270x590")  

mapArr=np.array(([113,62,31,63],
                 [50,101,72,47],
                 [92,10,40,12],
                 [83,21,128,16]))

xy=(['A','B','C','D','E','F'])


fig = matplotlib.figure.Figure() 
ax = fig.add_subplot()

heatmap = ax.imshow(mapArr,cmap="gray",interpolation='nearest',vmin=0, vmax=128)        

cb = fig.colorbar(heatmap)                                           

canvas = FigureCanvasTkAgg(fig, root)                                
canvas.get_tk_widget().place(x=60,y=60)                               

cursor = mplcursors.cursor(heatmap, hover=True)

@cursor.connect("add")
def on_add(sel):
    i,j = sel.target.index
    sel.annotation.set_text(mapArr[i,j])

tk.mainloop()

手动弹夹悬停箱

您可以在不使用mplcur标的情况下执行上述操作。这将通过创建注释并根据鼠标位置更改其位置和文本来完成。

import numpy as np
import matplotlib
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
import tkinter as tk

root = tk.Tk()
root.geometry("1270x590")  

mapArr=np.array(([113,62,31,63],
                 [50,101,72,47],
                 [92,10,40,12],
                 [83,21,128,16]))

xy=(['A','B','C','D','E','F'])


fig = matplotlib.figure.Figure() 
ax = fig.add_subplot()

heatmap = ax.imshow(mapArr,cmap="gray",interpolation='nearest',vmin=0, vmax=128)        

cb = fig.colorbar(heatmap)                                           

canvas = FigureCanvasTkAgg(fig, root)                                
canvas.get_tk_widget().place(x=60,y=60)                               

annot = ax.annotate("", xy=(0,0), xytext=(20,20), textcoords="offset points",
                    arrowprops=dict(arrowstyle="->"), visible=False,
                    bbox=dict(boxstyle="round", fc="w"))

def hover(event):
    if event.inaxes == ax:
        x,y = event.xdata, event.ydata
        j,i = np.round(np.array((x,y))).astype(int)
        annot.xy = (x,y)
        annot.set_text(str(mapArr[i,j]))
        annot.set_visible(True)
    else:
        annot.set_visible(False)
    fig.canvas.draw_idle()

canvas.mpl_connect("motion_notify_event", hover)

tk.mainloop()

Answer 2

您可以连接到coursor函数，它将更改注释中的文本。

cursor = mplcursors.cursor(hover=True)

@cursor.connect("add")
def on_mouse_move(sel):
    x = sel.target[0]
    y = sel.target[1]

    value = sel.artist.get_cursor_data(_Event(x, y))

    sel.annotation.set_text("value {} at ({:1.2f}, {:1.2f})".format(value, x,y))

为了获得价值，它需要namedtuple (我在游标的源代码中找到了它)

from collections import namedtuple

_Event = namedtuple('_Event', 'xdata ydata')

完整的工作示例(只需要代码，因此没有错误)

import tkinter as tk                                                    
import matplotlib.pyplot as plt
import mplcursors
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg

# --- data ---

mapArr = (
    [113, 62, 31, 63],
    [50, 101, 72, 47],
    [92, 10, 40, 12],
    [83, 21, 128, 16]
)

xy = ('A','B','C','D','E','F')

# --- main ---

root = tk.Tk()                                                          

figure, axis = plt.subplots(figsize=(8, 7))

canvas = FigureCanvasTkAgg(figure, root)                                
canvas.get_tk_widget().pack(fill='both', expand=True)

heatmap = axis.imshow(mapArr, cmap="gray", interpolation='nearest', vmin=0, vmax=128)        
heatmap.axes.get_xaxis().set_visible(False)                             
heatmap.axes.get_yaxis().set_visible(False)

colorbar = figure.colorbar(heatmap)                                           

#--- connect function to cursor

from collections import namedtuple
_Event = namedtuple('_Event', 'xdata ydata')

cursor = mplcursors.cursor(hover=True)

@cursor.connect("add")
def on_mouse_move(sel):
    x = sel.target[0]
    y = sel.target[1]

    value = sel.artist.get_cursor_data(_Event(x, y))

    sel.annotation.set_text("value {} at ({:1.2f}, {:1.2f})".format(value, x,y))

#--- 

root.mainloop()

编辑：使用@ImportanceOfBeingErnest示例，我在canvas.mpl_connect()版本中发现了我的错误所在，现在它起作用了。

此示例演示如何使用Checkbutton打开/关闭注释。

import tkinter as tk                                                    
import matplotlib.pyplot as plt
import mplcursors
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg

# --- data ---

mapArr = (
    [113, 62, 31, 63],
    [50, 101, 72, 47],
    [92, 10, 40, 12],
    [83, 21, 128, 16]
)

xy = ('A','B','C','D','E','F')

# --- functions ---

def on_mouse_move(event):
    if checkbuttonvariable.get() == 0:
        return

    if event.inaxes == axis:
        annotation.xy = (event.xdata, event.ydata)
        row = int(round(event.ydata))
        col = int(round(event.xdata))
        value = mapArr[row][col]
        annotation.set_text(str(value))
        annotation.set_visible(True)
    else:
        annotation.set_visible(False)
    canvas.draw()

# --- main ---

root = tk.Tk()                                                          

figure, axis = plt.subplots(figsize=(8, 7))

canvas = FigureCanvasTkAgg(figure, root)                                
canvas.get_tk_widget().pack(fill='both', expand=True)

heatmap = axis.imshow(mapArr, cmap="gray", interpolation='nearest', vmin=0, vmax=128)        
heatmap.axes.get_xaxis().set_visible(False)                             
heatmap.axes.get_yaxis().set_visible(False)

colorbar = figure.colorbar(heatmap)

# ---

annotation = axis.annotate("", xy=(0,0), xytext=(20,20), textcoords="offset points",
                    arrowprops=dict(arrowstyle="->"), visible=False,
                    bbox=dict(boxstyle="round", fc="w"))

canvas.mpl_connect('motion_notify_event', on_mouse_move)

# ---

checkbuttonvariable = tk.IntVar(value=1)
button = tk.Checkbutton(root, text='visible', variable=checkbuttonvariable)
button.pack()


root.mainloop()

Answer 3

您可以始终使用袖扣链接，我相信它们的功能已经内置在：https://plot.ly/ipython-notebooks/cufflinks/中。