python - Matplotlib 和 PyQt5 绘图图

Question

尝试在 PyQt5 和 Matplotlib 中使用 python 绘制饼图，但我遇到了一些问题。我可以有一个饼图和我想在其中显示的数据，但如果我在调用某个函数时向它提供新数据，我会尝试更新图表。

mplvl 是我要将图形添加到的小部件名称。

每次我调用这个函数时，它只会添加另一个子图。我试过清除情节，清除图形，但我不能只删除并重新绘制图形。我想我对 Matplotlib 的真正工作方式感到困惑，但我们将不胜感激。

import datetime
import calendar as cal
import sys

from PyQt5 import QtCore
from PyQt5.QtWidgets import QApplication, QDialog, QMainWindow, QMessageBox, QTableWidgetItem
from PyQt5.uic import loadUi

from matplotlib.figure import Figure
from matplotlib.backends.backend_qt5agg import (FigureCanvasQTAgg as FigureCanvas)


class MainWindow(QMainWindow):
    def __init__(self):
        super(MainWindow, self).__init__()
        loadUi('main.ui', self)

        self.date_from.setDate(QtCore.QDate(c_date.year, c_date.month, 1))
        self.date_to.setDate(QtCore.QDate(c_date.year, c_date.month, cal.monthrange(c_date.year, c_date.month)[1]))

        self.date_from.dateChanged.connect(self.fcn_date_changed)
        self.date_to.dateChanged.connect(self.fcn_date_changed)


    def fcn_date_changed(self):
        print("from: " + self.date_from.text() + " to: " + self.date_to.text())

        labels = 'Frogs', 'Hogs', 'Dogs', 'Logs'
        sizes = [15, 30, 45, 10]

        fig = Figure()
        ax1 = fig.add_subplot(111)
        ax1.set_title('Percentage Spending by Category')
        ax1.pie(sizes, labels=labels, autopct='%1.1f%%', shadow=False, startangle=90)
        main.canvas = FigureCanvas(fig)
        main.mplvl.addWidget(main.canvas)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    main_window = MainWindow()
    main_window.show()
    sys.exit(app.exec_())

下面是main.ui:

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>861</width>
    <height>611</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QPushButton" name="btn_add_item">
    <property name="geometry">
     <rect>
      <x>10</x>
      <y>10</y>
      <width>71</width>
      <height>41</height>
     </rect>
    </property>
    <property name="text">
     <string>Add Item</string>
    </property>
   </widget>
   <widget class="QPushButton" name="btn_edit_item">
    <property name="geometry">
     <rect>
      <x>190</x>
      <y>540</y>
      <width>81</width>
      <height>23</height>
     </rect>
    </property>
    <property name="text">
     <string>Edit Item</string>
    </property>
   </widget>
   <widget class="QListWidget" name="recent_items">
    <property name="geometry">
     <rect>
      <x>10</x>
      <y>130</y>
      <width>351</width>
      <height>401</height>
     </rect>
    </property>
   </widget>
   <widget class="QLabel" name="lbl_recent_items">
    <property name="geometry">
     <rect>
      <x>10</x>
      <y>110</y>
      <width>251</width>
      <height>16</height>
     </rect>
    </property>
    <property name="text">
     <string>Recent Items</string>
    </property>
   </widget>
   <widget class="QPushButton" name="btn_delete_item">
    <property name="geometry">
     <rect>
      <x>280</x>
      <y>540</y>
      <width>81</width>
      <height>23</height>
     </rect>
    </property>
    <property name="text">
     <string>Delete Item</string>
    </property>
   </widget>
   <widget class="QWidget" name="mplwindow" native="true">
    <property name="geometry">
     <rect>
      <x>380</x>
      <y>130</y>
      <width>471</width>
      <height>401</height>
     </rect>
    </property>
    <property name="sizePolicy">
     <sizepolicy hsizetype="Preferred" vsizetype="Preferred">
      <horstretch>0</horstretch>
      <verstretch>0</verstretch>
     </sizepolicy>
    </property>
    <layout class="QVBoxLayout" name="mplvl"/>
   </widget>
   <widget class="QPushButton" name="btn_view_items">
    <property name="geometry">
     <rect>
      <x>280</x>
      <y>100</y>
      <width>81</width>
      <height>23</height>
     </rect>
    </property>
    <property name="text">
     <string>View Items</string>
    </property>
   </widget>
   <widget class="QDateEdit" name="date_from">
    <property name="geometry">
     <rect>
      <x>110</x>
      <y>60</y>
      <width>110</width>
      <height>21</height>
     </rect>
    </property>
    <property name="calendarPopup">
     <bool>true</bool>
    </property>
   </widget>
   <widget class="QDateEdit" name="date_to">
    <property name="geometry">
     <rect>
      <x>250</x>
      <y>60</y>
      <width>110</width>
      <height>21</height>
     </rect>
    </property>
    <property name="calendarPopup">
     <bool>true</bool>
    </property>
   </widget>
   <widget class="QLabel" name="lbl_showing_items1">
    <property name="geometry">
     <rect>
      <x>10</x>
      <y>60</y>
      <width>101</width>
      <height>21</height>
     </rect>
    </property>
    <property name="text">
     <string>Showing items from: </string>
    </property>
   </widget>
   <widget class="QLabel" name="lbl_showing_items1_2">
    <property name="geometry">
     <rect>
      <x>230</x>
      <y>60</y>
      <width>21</width>
      <height>21</height>
     </rect>
    </property>
    <property name="text">
     <string>to:</string>
    </property>
   </widget>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>861</width>
     <height>21</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

Answer 1

逻辑是:

• 创建一个AxesSubplot，
• 清理它，
• 调用实现绘图的函数(在您的例子中是pie())和
• 调用draw()绘制它。

    # ...
    self.date_to.dateChanged.connect(self.fcn_date_changed)

    fig = Figure()
    self.canvas = FigureCanvas(fig)
    self.mplvl.addWidget(self.canvas)
    self.ax1 = fig.add_subplot(111)
    self.ax1.pie([])

def fcn_date_changed(self):
    self.ax1.clear()
    self.ax1.set_title("Percentage Spending by Category")
    print("from: " + self.date_from.text() + " to: " + self.date_to.text())
    labels = "Frogs", "Hogs", "Dogs", "Logs"
    sizes = [15, 30, 45, 10]
    self.ax1.pie(
        sizes, labels=labels, autopct="%1.1f%%", shadow=False, startangle=90
    )
    self.ax1.figure.canvas.draw()