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matplotlib 矩形选区 matplotlib部件之矩形选区(RectangleSelector)的实现

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想了解matplotlib部件之矩形选区(RectangleSelector)的实现的相关内容吗,mighty13在本文为您仔细讲解matplotlib 矩形选区的相关知识和一些Code实例,欢迎阅读和指正,我们先划重点:matplotlib,矩形选区,下面大家一起来学习吧。

矩形选区概述

矩形选区是一种常见的对象选择方式,这个名词最常见于Photoshop中,用于在一个子图选择鼠标拖动的矩形区域中的元素,在matplotlib中的矩形选区属于部件(widgets),matplotlib中的部件都是中性(neutral )的,即与具体后端实现无关。

矩形选区具体实现定义为matplotlib.widgets.RectangleSelector类,继承关系为:Widget->AxesWidget->_SelectorWidget->RectangleSelector。

RectangleSelector类的签名为class matplotlib.widgets.RectangleSelector(ax, onselect, drawtype='box', minspanx=0, minspany=0, useblit=False, lineprops=None, rectprops=None, spancoords='data', button=None, maxdist=10, marker_props=None, interactive=False, state_modifier_keys=None)

RectangleSelector类构造函数的参数为:

案例

官方案例,https://matplotlib.org/gallery/widgets/rectangle_selector.html

案例说明

拖动鼠标画出矩形选区,默认为交互模式,显示选区框,按esc键取消选区,控制台显示选区的坐标和使用的鼠标键。按t键切换矩形选区功能的激活状态,非激活状态矩形选区功能不生效。


控制台输出:

(0.74, -0.38) --> (8.90, 0.75)
 The buttons you used were: 1 1

代码分析

from matplotlib.widgets import RectangleSelector
import numpy as np
import matplotlib.pyplot as plt

# 矩形选区选择时的回调函数
def line_select_callback(eclick, erelease):
  """
  Callback for line selection.

  *eclick* and *erelease* are the press and release events.
  """
  x1, y1 = eclick.xdata, eclick.ydata
  x2, y2 = erelease.xdata, erelease.ydata
  print(f"({x1:3.2f}, {y1:3.2f}) --> ({x2:3.2f}, {y2:3.2f})")
  print(f" The buttons you used were: {eclick.button} {erelease.button}")

# 激活状态快捷键回调函数,active属性和set_active方法继承自_SelectorWidget类
def toggle_selector(event):
  print(' Key pressed.')
  if event.key == 't':
    if RS.active:
      print(' RectangleSelector deactivated.')
      RS.set_active(False)
    else:
      print(' RectangleSelector activated.')
      RS.set_active(True)

# 绘图
fig, ax = plt.subplots()
N = 100000 # If N is large one can see improvement by using blitting.
x = np.linspace(0, 10, N)

ax.plot(x, np.sin(2*np.pi*x)) # plot something
ax.set_title(
  "Click and drag to draw a rectangle.\n"
  "Press 't' to toggle the selector on and off.")

# 构造矩形选区实例,选取外观为矩形框,鼠标键为左键右键有效,允许保留选区
# drawtype is 'box' or 'line' or 'none'
RS = RectangleSelector(ax, line_select_callback,
                    drawtype='box', useblit=True,
                    button=[1, 3], # disable middle button
                    minspanx=5, minspany=5,
                    spancoords='pixels',
                    interactive=True)
# 绑定键盘事件,实现切换矩形选区激活状态功能
fig.canvas.mpl_connect('key_press_event', toggle_selector)
plt.show()

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