Python 使用 matplotlib 存储鼠标点击事件坐标
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Store mouse click event coordinates with matplotlib
提问by smashbro
I am trying to implement a simple mouse click event in matplotlib. I wish to plot a figure then use the mouse to select the lower and upper limits for integration. So far I am able to print the coordinates to screen but not store them for later use in the program. I would also like to exit the connection to the figure after the second mouse click.
我正在尝试在 matplotlib 中实现一个简单的鼠标点击事件。我想绘制一个图形，然后使用鼠标选择积分的下限和上限。到目前为止，我能够将坐标打印到屏幕上，但不能存储它们以供以后在程序中使用。我还想在第二次单击鼠标后退出与图形的连接。
Below is the code which currently plots and then prints the coordinates.
下面是当前绘制然后打印坐标的代码。
My Question(s):
我的问题：
How can I store coordinates from the figure to list? i.e. click = [xpos, ypos]
如何将图形中的坐标存储到列表中？即点击 = [xpos, ypos]
Is it possible to get two sets of x coordinates in order to do a simple integration over that section of line?
是否有可能获得两组 x 坐标以便对该线段进行简单的积分？
import numpy as np
import matplotlib.pyplot as plt
x = np.arange(-10,10)
y = x**2
fig = plt.figure()
ax = fig.add_subplot(111)
ax.plot(x,y)
def onclick(event):
global ix, iy
ix, iy = event.xdata, event.ydata
print 'x = %d, y = %d'%(
ix, iy)
global coords
coords = [ix, iy]
return coords
for i in xrange(0,1):
cid = fig.canvas.mpl_connect('button_press_event', onclick)
plt.show()
采纳答案by otterb
mpl_connect needs to be called just once to connect the event to event handler. It will start listening to click event until you disconnect. And you can use
mpl_connect 只需调用一次即可将事件连接到事件处理程序。它将开始侦听单击事件，直到您断开连接。你可以使用
fig.canvas.mpl_disconnect(cid)
to disconnect the event hook.
断开事件挂钩。
What you want to do is something like:
你想要做的是：
import numpy as np
import matplotlib.pyplot as plt
x = np.arange(-10,10)
y = x**2
fig = plt.figure()
ax = fig.add_subplot(111)
ax.plot(x,y)
coords = []
def onclick(event):
global ix, iy
ix, iy = event.xdata, event.ydata
print 'x = %d, y = %d'%(
ix, iy)
global coords
coords.append((ix, iy))
if len(coords) == 2:
fig.canvas.mpl_disconnect(cid)
return coords
cid = fig.canvas.mpl_connect('button_press_event', onclick)
回答by smashbro
Thanks to otterb for providing the answer! I've added in a little function taken from here... Find nearest value in numpy array
感谢 otterb 提供答案！我添加了一个从这里获取的小函数...... 在 numpy 数组中找到最近的值
In all this code will plot, wait for selection of x points and then return the indices of the x array needed for any integration, summations etc.
在所有这些代码中，等待选择 x 点，然后返回任何积分、求和等所需的 x 数组的索引。
Ta,
塔，
import numpy as np
import matplotlib.pyplot as plt
from scipy.integrate import trapz
def find_nearest(array,value):
idx = (np.abs(array-value)).argmin()
return array[idx]
# Simple mouse click function to store coordinates
def onclick(event):
global ix, iy
ix, iy = event.xdata, event.ydata
# print 'x = %d, y = %d'%(
# ix, iy)
# assign global variable to access outside of function
global coords
coords.append((ix, iy))
# Disconnect after 2 clicks
if len(coords) == 2:
fig.canvas.mpl_disconnect(cid)
plt.close(1)
return
x = np.arange(-10,10)
y = x**2
fig = plt.figure(1)
ax = fig.add_subplot(111)
ax.plot(x,y)
coords = []
# Call click func
cid = fig.canvas.mpl_connect('button_press_event', onclick)
plt.show(1)
# limits for integration
ch1 = np.where(x == (find_nearest(x, coords[0][0])))
ch2 = np.where(x == (find_nearest(x, coords[1][0])))
# Calculate integral
y_int = trapz(y[ch1[0][0]:ch2[0][0]], x = x[ch1[0][0]:ch2[0][0]])
print ''
print 'Integral between '+str(coords[0][0])+ ' & ' +str(coords[1][0])
print y_int
