手写识别数字（画板计算器，python，最简单的三层神经网络）

含有五个类，神经网络类、两个类用于实现画板、两个类用于实现计算器。
画板识别需要先训练网络后，导出两权重，才能使用。

神经网络类

import numpy
import scipy.special
import matplotlib.pyplot
import pylab
from tensorflow.examples.tutorials.mnist import input_data
from PIL import Image

class neuralNetwork:
    def __init__(self, inputnodes, hiddennodes, outputnodes, learningrate):
        # inputnodes输入节点数目，即图像的宽*高=28*28=784
        self.inodes = inputnodes
        self.hnodes = hiddennodes
        self.onodes = outputnodes

        # 初始化权重服从正态分布
        self.wih = numpy.random.normal(0.0, pow(self.hnodes, -0.5), (self.hnodes, self.inodes))
        self.who = numpy.random.normal(0.0, pow(self.onodes, -0.5), (self.onodes, self.hnodes))

        self.lr = learningrate;

        # 激活函数
        self.activation_function = lambda x: scipy.special.expit(x)
        pass

    def  set_wih_who(self):
        self.wih = numpy.loadtxt('MNIST_data/wih.txt')
        self.who = numpy.loadtxt('MNIST_data/who.txt')

    def train(self, inputs_list, targets_list):
        inputs = numpy.array(inputs_list, ndmin=2).T
        targets = numpy.array(targets_list, ndmin=2).T

        # 正向推算
        hidden_inputs = numpy.dot(self.wih, inputs)
        hidden_outputs = self.activation_function(hidden_inputs)

        final_inputs = numpy.dot(self.who, hidden_outputs)
        final_outputs = self.activation_function(final_inputs)

        # 误差反向推算
        output_errors = targets - final_outputs
        self.who += self.lr * numpy.dot((output_errors * final_outputs * (1.0 - final_outputs)),
                                        numpy.transpose(hidden_outputs))

        hidden_errors = numpy.dot(self.who.T, output_errors)
        self.wih += self.lr * numpy.dot((hidden_errors * hidden_outputs * (1.0 - hidden_outputs)),
                                        numpy.transpose(inputs))
        pass

    def query(self, inputs_list):
        inputs = numpy.array(inputs_list, ndmin=2).T
        hidden_inputs = numpy.dot(self.wih, inputs)
        hidden_outputs = self.activation_function(hidden_inputs)

        final_inputs = numpy.dot(self.who, hidden_outputs)
        final_outputs = self.activation_function(final_inputs)

        return final_outputs

    def mytest(self, fname):
        im = Image.open(fname).convert('L')
        im = im.resize((28, 28))
        tmp = numpy.array(im)
        vec = tmp.ravel()
        for i in range(len(vec)):
            if vec[i] == 0:
                vec[i] = 255
            else:
                vec[i] = 0
        myinputs = (numpy.asfarray(vec[0:]) / 255.0 * 0.99) + 0.01
        # print(myinputs)
        myoutputs = self.query(myinputs)
        label = numpy.argmax(myoutputs)
        print(label)
        pass

    def mytest_image(self, img):
        im = img
        im = im.resize((28, 28))
        tmp = numpy.array(im)
        vec = tmp.ravel()
        for i in range(len(vec)):
            if vec[i] == 0:
                vec[i] = 255
            else:
                vec[i] = 0
        myinputs = (numpy.asfarray(vec[0:]) / 255.0 * 0.99) + 0.01
        # print(myinputs)
        myoutputs = self.query(myinputs)
        label = numpy.argmax(myoutputs)
        return label

if __name__ == "__main__":
    # 训练神经网络
    input_nodes = 784
    hidden_nodes = 100
    output_nodes = 10

    learning_rate = 0.1

    n = neuralNetwork(input_nodes, hidden_nodes, output_nodes, learning_rate)

    mnist = input_data.read_data_sets('MNIST_data/', one_hot=True)
    epochs = 20

    for e in range(epochs):
        for i in range(10000):

            inputs = mnist.train.images[i]

            targets = numpy.zeros(output_nodes) + 0.01
            targets[numpy.argmax(mnist.train.labels[i])] = 0.99

            n.train(inputs, targets)
            pass
        pass

# 测试神经网络

    scorecard = []

    for i in range(100):


        # image_array = numpy.asfarray(record_value[1:]).reshape(28, 28)
        # matplotlib.pyplot.imshow(image_array, cmap="Greys", interpolation='None')
        # pylab.show()

        if i==1:

            numpy.savetxt('wih.txt',n.wih)#(100,784)
            numpy.savetxt('who.txt',n.who)#(10,100)

        inputs = mnist.test.images[i]
        correct_label = numpy.argmax(mnist.test.labels[i])

        outputs = n.query(inputs)
        label = numpy.argmax(outputs)

        if (label == correct_label):
            print("right:", label)
            scorecard.append(1)
        else:
            print("wrong:", label, "v", correct_label)
            scorecard.append(0)
            pass
        pass

    scorecard_array = numpy.asarray(scorecard)
    print("performance= ", scorecard_array.sum() / scorecard_array.size)

两个画板类

from PyQt5.Qt import QWidget, QColor, QPixmap, QIcon, QSize, QCheckBox
from PyQt5.QtWidgets import QHBoxLayout, QVBoxLayout, QPushButton, QSplitter,\
    QComboBox, QLabel, QSpinBox, QFileDialog
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PaintBoard import PaintBoard
from my_neuralNetwork import *
import os
os.environ["CUDA_VISIBLE_DEVICES"] = "-1"

#画板类
class MainWidget(QWidget):

    Signal_parp = pyqtSignal(str)
    def __init__(self, Parent=None):
        super().__init__(Parent)
        
        self.__InitData() #先初始化数据，再初始化界面

        self.__InitView()


    def __InitData(self):
        '''
                  初始化成员变量
        '''
        self.__paintBoard = PaintBoard(self)
        #获取颜色列表(字符串类型)
        self.__colorList = QColor.colorNames()

        
    def __InitView(self):
        '''
                  初始化界面
        '''
        self.setFixedSize(740,480)
        self.setWindowTitle("PaintBoard Example PyQt5")

        #新建一个水平布局作为本窗体的主布局
        self.main_layout = QHBoxLayout(self)
        #设置主布局内边距以及控件间距为10px
        self.main_layout.setSpacing(10)
    
        #在主界面左侧放置画板
        self.main_layout.addWidget(self.__paintBoard)
        
        #新建垂直子布局用于放置按键
        self.sub_layout = QVBoxLayout()
        
        #设置此子布局和内部控件的间距为10px
        self.sub_layout.setContentsMargins(10, 10, 10, 10)

        self.__btn_Clear = QPushButton("清空画板")
        self.__btn_Clear.setParent(self) #设置父对象为本界面
       
        #将按键按下信号与画板清空函数相关联
        self.__btn_Clear.clicked.connect(self.__paintBoard.Clear) 
        self.sub_layout.addWidget(self.__btn_Clear)
        
        self.__btn_Quit = QPushButton("退出")
        self.__btn_Quit.setParent(self) #设置父对象为本界面
        self.__btn_Quit.clicked.connect(self.Quit)
        self.sub_layout.addWidget(self.__btn_Quit)
        
        self.__btn_Save = QPushButton("保存作品")
        self.__btn_Save.setParent(self)
        self.__btn_Save.clicked.connect(self.on_btn_Save_Clicked)
        self.sub_layout.addWidget(self.__btn_Save)

        self.__btn_Test = QPushButton("识别")
        self.__btn_Test.setParent(self)
        self.__btn_Test.clicked.connect(self.on_btn_Test_Clicked)
        self.sub_layout.addWidget(self.__btn_Test)

        
        self.__cbtn_Eraser = QCheckBox("  使用橡皮擦")
        self.__cbtn_Eraser.setParent(self)
        self.__cbtn_Eraser.clicked.connect(self.on_cbtn_Eraser_clicked)
        self.sub_layout.addWidget(self.__cbtn_Eraser)
        
        self.splitter = QSplitter(self) #占位符
        self.sub_layout.addWidget(self.splitter)
        
        self.__label_penThickness = QLabel(self)
        self.__label_penThickness.setText("画笔粗细")
        self.__label_penThickness.setFixedHeight(30)
        self.sub_layout.addWidget(self.__label_penThickness)
        
        self.__spinBox_penThickness = QSpinBox(self)
        self.__spinBox_penThickness.setMaximum(20)
        self.__spinBox_penThickness.setMinimum(2)
        self.__spinBox_penThickness.setValue(20) #默认粗细为10
        self.__spinBox_penThickness.setSingleStep(2) #最小变化值为2
        self.__spinBox_penThickness.valueChanged.connect(self.on_PenThicknessChange)#关联spinBox值变化信号和函数on_PenThicknessChange
        self.sub_layout.addWidget(self.__spinBox_penThickness)
        
        self.__label_penColor = QLabel(self)
        self.__label_penColor.setText("画笔颜色")
        self.__label_penColor.setFixedHeight(20)
        self.sub_layout.addWidget(self.__label_penColor)
        
        self.__comboBox_penColor = QComboBox(self)
        self.__fillColorList(self.__comboBox_penColor) #用各种颜色填充下拉列表
        self.__comboBox_penColor.currentIndexChanged.connect(self.on_PenColorChange) #关联下拉列表的当前索引变更信号与函数on_PenColorChange
        self.sub_layout.addWidget(self.__comboBox_penColor)

        self.main_layout.addLayout(self.sub_layout) #将子布局加入主布局



    def __fillColorList(self, comboBox):

        index_black = 0
        index = 0
        for color in self.__colorList: 
            if color == "black":
                index_black = index
            index += 1
            pix = QPixmap(70,20)
            pix.fill(QColor(color))
            comboBox.addItem(QIcon(pix),None)
            comboBox.setIconSize(QSize(70,20))
            comboBox.setSizeAdjustPolicy(QComboBox.AdjustToContents)

        comboBox.setCurrentIndex(index_black)

        
    def on_PenColorChange(self):
        color_index = self.__comboBox_penColor.currentIndex()
        color_str = self.__colorList[color_index]
        self.__paintBoard.ChangePenColor(color_str)


    def on_PenThicknessChange(self):
        penThickness = self.__spinBox_penThickness.value()
        self.__paintBoard.ChangePenThickness(penThickness)

    
    def on_btn_Save_Clicked(self):
        savePath = QFileDialog.getSaveFileName(self, 'Save Your Paint', '.\\', '*.png')
        print(savePath)
        if savePath[0] == "":
            print("Save cancel")
            return
        image = self.__paintBoard.GetContentAsQImage()
        image.save(savePath[0])


    def on_btn_Test_Clicked(self):
        image = self.__paintBoard.GetContentAsQImage()
        image.save("qaq1.png","PNG")
        im = Image.open('qaq1.png').convert('L')
        input_nodes = 784
        hidden_nodes = 100
        output_nodes = 10
        learning_rate = 0.05
        n = neuralNetwork(input_nodes, hidden_nodes, output_nodes, learning_rate)
        n.set_wih_who()
        data_str = str(n.mytest_image(im))
        self.Signal_parp.emit(data_str)
        # return data_str

    def on_cbtn_Eraser_clicked(self):
        if self.__cbtn_Eraser.isChecked():
            self.__paintBoard.EraserMode = True #进入橡皮擦模式
        else:
            self.__paintBoard.EraserMode = False #退出橡皮擦模式

        

    def Quit(self):
        self.close()

from PyQt5.QtWidgets import QWidget
from PyQt5.Qt import QPixmap, QPainter, QPoint, QPaintEvent, QMouseEvent, QPen,QColor, QSize
from PyQt5.QtCore import Qt

#画板类
class PaintBoard(QWidget):


    def __init__(self, Parent=None):

        super().__init__(Parent)

        self.__InitData() #先初始化数据，再初始化界面
        self.__InitView()

    def __InitData(self):
        
        self.__size = QSize(480,460)
        
        #新建QPixmap作为画板，尺寸为__size
        self.__board = QPixmap(self.__size)
        self.__board.fill(Qt.white) #用白色填充画板
        
        self.__IsEmpty = True #默认为空画板 
        self.EraserMode = False #默认为禁用橡皮擦模式
        
        self.__lastPos = QPoint(0,0)#上一次鼠标位置
        self.__currentPos = QPoint(0,0)#当前的鼠标位置
        
        self.__painter = QPainter()#新建绘图工具
        
        self.__thickness = 20       #默认画笔粗细为10px
        self.__penColor = QColor("black")#设置默认画笔颜色为黑色
        self.__colorList = QColor.colorNames() #获取颜色列表

    def __InitView(self):
        #设置界面的尺寸为__size
        self.setFixedSize(self.__size)

    def Clear(self):
        #清空画板
        self.__board.fill(Qt.white)
        self.update()
        self.__IsEmpty = True
        
    def ChangePenColor(self, color="black"):
        #改变画笔颜色
        self.__penColor = QColor(color)
        
    def ChangePenThickness(self, thickness=20):
        #改变画笔粗细
        self.__thickness = thickness
        
    def IsEmpty(self):
        #返回画板是否为空
        return self.__IsEmpty
    
    def GetContentAsQImage(self):
        #获取画板内容（返回QImage）
        image = self.__board.toImage()
        return image
        
    def paintEvent(self, paintEvent):
        #绘图事件
        #绘图时必须使用QPainter的实例，此处为__painter
        #绘图在begin()函数与end()函数间进行
        #begin(param)的参数要指定绘图设备，即把图画在哪里
        #drawPixmap用于绘制QPixmap类型的对象
        self.__painter.begin(self)
        # 0,0为绘图的左上角起点的坐标，__board即要绘制的图
        self.__painter.drawPixmap(0,0,self.__board)
        self.__painter.end()
        
    def mousePressEvent(self, mouseEvent):
        #鼠标按下时，获取鼠标的当前位置保存为上一次位置
        self.__currentPos =  mouseEvent.pos()
        self.__lastPos = self.__currentPos
        
        
    def mouseMoveEvent(self, mouseEvent):
        #鼠标移动时，更新当前位置，并在上一个位置和当前位置间画线
        self.__currentPos =  mouseEvent.pos()
        self.__painter.begin(self.__board)
        
        if self.EraserMode == False:
            #非橡皮擦模式
            self.__painter.setPen(QPen(self.__penColor,self.__thickness)) #设置画笔颜色，粗细
        else:
            #橡皮擦模式下画笔为纯白色，粗细为10
            self.__painter.setPen(QPen(Qt.white,10))
            
        #画线    
        self.__painter.drawLine(self.__lastPos, self.__currentPos)
        self.__painter.end()
        self.__lastPos = self.__currentPos
                
        self.update() #更新显示
        
    def mouseReleaseEvent(self, mouseEvent):
        self.__IsEmpty = False #画板不再为空

两个计算器类

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(647, 675)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.b_1 = QtWidgets.QPushButton(self.centralwidget)
        self.b_1.setGeometry(QtCore.QRect(10, 330, 71, 71))
        self.b_1.setObjectName("b_1")
        self.b_2 = QtWidgets.QPushButton(self.centralwidget)
        self.b_2.setGeometry(QtCore.QRect(80, 330, 71, 71))
        self.b_2.setObjectName("b_2")
        self.b_3 = QtWidgets.QPushButton(self.centralwidget)
        self.b_3.setGeometry(QtCore.QRect(150, 330, 71, 71))
        self.b_3.setObjectName("b_3")
        self.b_6 = QtWidgets.QPushButton(self.centralwidget)
        self.b_6.setGeometry(QtCore.QRect(150, 400, 71, 71))
        self.b_6.setObjectName("b_6")
        self.b_4 = QtWidgets.QPushButton(self.centralwidget)
        self.b_4.setGeometry(QtCore.QRect(10, 400, 71, 71))
        self.b_4.setObjectName("b_4")
        self.b_5 = QtWidgets.QPushButton(self.centralwidget)
        self.b_5.setGeometry(QtCore.QRect(80, 400, 71, 71))
        self.b_5.setObjectName("b_5")
        self.b_8 = QtWidgets.QPushButton(self.centralwidget)
        self.b_8.setGeometry(QtCore.QRect(80, 470, 71, 71))
        self.b_8.setObjectName("b_8")
        self.b_9 = QtWidgets.QPushButton(self.centralwidget)
        self.b_9.setGeometry(QtCore.QRect(150, 470, 71, 71))
        self.b_9.setObjectName("b_9")
        self.b_7 = QtWidgets.QPushButton(self.centralwidget)
        self.b_7.setGeometry(QtCore.QRect(10, 470, 71, 71))
        self.b_7.setObjectName("b_7")
        self.b_eq = QtWidgets.QPushButton(self.centralwidget)
        self.b_eq.setGeometry(QtCore.QRect(220, 540, 141, 71))
        self.b_eq.setObjectName("b_eq")

        self.b_net = QtWidgets.QPushButton(self.centralwidget)
        self.b_net.setGeometry(QtCore.QRect(150, 540, 71, 71))
        self.b_net.setObjectName("b_net")

        self.b_mod = QtWidgets.QPushButton(self.centralwidget)
        self.b_mod.setGeometry(QtCore.QRect(220, 400, 71, 71))
        self.b_mod.setObjectName("b_mod")
        self.b_bra_l = QtWidgets.QPushButton(self.centralwidget)
        self.b_bra_l.setGeometry(QtCore.QRect(220, 330, 71, 71))
        self.b_bra_l.setObjectName("b_bra_l")
        self.b_div = QtWidgets.QPushButton(self.centralwidget)
        self.b_div.setGeometry(QtCore.QRect(220, 260, 71, 71))
        self.b_div.setObjectName("b_div")
        self.b_add = QtWidgets.QPushButton(self.centralwidget)
        self.b_add.setGeometry(QtCore.QRect(10, 260, 71, 71))
        self.b_add.setObjectName("b_add")
        self.b_sub = QtWidgets.QPushButton(self.centralwidget)
        self.b_sub.setGeometry(QtCore.QRect(80, 260, 71, 71))
        self.b_sub.setObjectName("b_sub")
        self.b_mul = QtWidgets.QPushButton(self.centralwidget)
        self.b_mul.setGeometry(QtCore.QRect(150, 260, 71, 71))
        self.b_mul.setObjectName("b_mul")
        self.b_pow = QtWidgets.QPushButton(self.centralwidget)
        self.b_pow.setGeometry(QtCore.QRect(290, 260, 71, 71))
        self.b_pow.setObjectName("b_pow")
        self.b_pai = QtWidgets.QPushButton(self.centralwidget)
        self.b_pai.setGeometry(QtCore.QRect(290, 400, 71, 71))
        self.b_pai.setObjectName("b_pai")
        self.b_bra_r = QtWidgets.QPushButton(self.centralwidget)
        self.b_bra_r.setGeometry(QtCore.QRect(290, 330, 71, 71))
        self.b_bra_r.setObjectName("b_bra_r")
        self.l_hist = QtWidgets.QListWidget(self.centralwidget)
        self.l_hist.setGeometry(QtCore.QRect(380, 10, 256, 601))
        self.l_hist.setObjectName("l_hist")
        self.e_view = QtWidgets.QTextEdit(self.centralwidget)
        self.e_view.setGeometry(QtCore.QRect(10, 10, 351, 231))
        font = QtGui.QFont()
        font.setFamily("Adobe Caslon Pro Bold")
        font.setPointSize(22)
        font.setBold(True)
        font.setWeight(75)
        self.e_view.setFont(font)
        self.e_view.setObjectName("e_view")
        self.b_0 = QtWidgets.QPushButton(self.centralwidget)
        self.b_0.setGeometry(QtCore.QRect(80, 540, 71, 71))
        self.b_0.setObjectName("b_0")
        self.b_pt = QtWidgets.QPushButton(self.centralwidget)
        self.b_pt.setGeometry(QtCore.QRect(10, 540, 71, 71))
        self.b_pt.setObjectName("b_pt")
        self.b_del = QtWidgets.QPushButton(self.centralwidget)
        self.b_del.setGeometry(QtCore.QRect(220, 470, 71, 71))
        self.b_del.setObjectName("b_del")
        self.b_clc = QtWidgets.QPushButton(self.centralwidget)
        self.b_clc.setGeometry(QtCore.QRect(290, 470, 71, 71))
        self.b_clc.setObjectName("b_clc")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 647, 30))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.b_1.setText(_translate("MainWindow", "1"))
        self.b_2.setText(_translate("MainWindow", "2"))
        self.b_3.setText(_translate("MainWindow", "3"))
        self.b_6.setText(_translate("MainWindow", "6"))
        self.b_4.setText(_translate("MainWindow", "4"))
        self.b_5.setText(_translate("MainWindow", "5"))
        self.b_8.setText(_translate("MainWindow", "8"))
        self.b_9.setText(_translate("MainWindow", "9"))
        self.b_7.setText(_translate("MainWindow", "7"))
        self.b_eq.setText(_translate("MainWindow", "="))
        self.b_mod.setText(_translate("MainWindow", "%"))
        self.b_bra_l.setText(_translate("MainWindow", "("))
        self.b_div.setText(_translate("MainWindow", "/"))
        self.b_add.setText(_translate("MainWindow", "+"))
        self.b_sub.setText(_translate("MainWindow", "-"))
        self.b_mul.setText(_translate("MainWindow", "*"))
        self.b_pow.setText(_translate("MainWindow", "^"))
        self.b_pai.setText(_translate("MainWindow", "π"))
        self.b_bra_r.setText(_translate("MainWindow", ")"))
        self.b_0.setText(_translate("MainWindow", "0"))
        self.b_pt.setText(_translate("MainWindow", "."))
        self.b_del.setText(_translate("MainWindow", "删除"))
        self.b_clc.setText(_translate("MainWindow", "清空"))
        self.b_net.setText(_translate("MainWindow", "识别"))

from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from calc_interface import Ui_MainWindow
import os,sys

from MainWidget import *

global e_view

pluginsPath='PyQt5/Qt/plugins'
if os.path.exists(pluginsPath):
    QApplication.addLibraryPath(pluginsPath)

class MyMainWindow(QMainWindow, Ui_MainWindow):

    def forge_link(self):
        self.b_0.clicked.connect(self.button_event(0))
        self.b_1.clicked.connect(self.button_event(1))
        self.b_2.clicked.connect(self.button_event(2))
        self.b_3.clicked.connect(self.button_event(3))
        self.b_4.clicked.connect(self.button_event(4))
        self.b_5.clicked.connect(self.button_event(5))
        self.b_6.clicked.connect(self.button_event(6))
        self.b_7.clicked.connect(self.button_event(7))
        self.b_8.clicked.connect(self.button_event(8))
        self.b_9.clicked.connect(self.button_event(9))
        self.b_add.clicked.connect(self.button_event('+'))
        self.b_sub.clicked.connect(self.button_event('-'))
        self.b_mul.clicked.connect(self.button_event('*'))
        self.b_div.clicked.connect(self.button_event('/'))
        self.b_pow.clicked.connect(self.button_event('**'))
        self.b_bra_l.clicked.connect(self.button_event('('))
        self.b_bra_r.clicked.connect(self.button_event(')'))
        self.b_mod.clicked.connect(self.button_event('%'))
        self.b_pai.clicked.connect(self.button_event('3.1415926'))
        self.b_pt.clicked.connect(self.button_event('.'))
        self.b_del.clicked.connect(self.delete_event)
        self.b_clc.clicked.connect(self.clear_event)
        self.b_eq.clicked.connect(self.calc_complish)
        self.b_net.clicked.connect(self.net)

    def __init__(self, parent=None):
        super(MyMainWindow, self).__init__(parent)
        self.setupUi(self)
        self.forge_link()   #连接槽函数

    def button_event(self,arg):
        # print(dir(self.e_view))
        global e_view
        e_view=self.e_view
        def fun():      #返回一个自定义的槽函数
            global e_view
            txt = e_view.toPlainText()
            e_view.setText(txt + str(arg))
        return fun

    def calc_complish(self):
        txt=self.e_view.toPlainText()
        ans=''
        try:
            ans=str(eval(txt))
        except BaseException:
            ans='MathError'
        # print(ans)
        self.clear_event()
        self.e_view.setText(ans)
        self.l_hist.addItem(txt+'='+ans)

    def clear_event(self):
        self.e_view.setText('')

    def delete_event(self):
        txt = self.e_view.toPlainText()
        txt=txt[:len(txt)-1]
        self.e_view.setText(txt)

    def net(self):
        # app = QApplication(sys.argv)
        # mainWidget = MainWidget()  # 新建一个主界面


        mainWidget.Signal_parp.connect(self.deal_emit_slot)
        mainWidget.show()  # 显示主界面
        # mainWidget.Signal_OneParameter.connect(self.deal_emit_slot)
        # sys.exit(app.exec_())  # 进入消息循环


    def deal_emit_slot(self, data_str):
        txt = e_view.toPlainText()
        e_view.setText(txt + data_str)

if __name__ == '__main__':
    app=QApplication(sys.argv)
    myWin=MyMainWindow()
    mainWidget = MainWidget()  # 新建一个主界面

    myWin.show()
    sys.exit(app.exec())