Question

我正在尝试学习PyQt5并在GUI上显示Matplotlib图。现在，我尝试使用CSV文件中的Menubar加载按钮加载数据。我能成功地做到这一点。我的问题是现在在图表上显示这些数据。这是我的代码：

import sys
from PyQt5.QtWidgets import (QMainWindow, QAction, qApp, QApplication, QPushButton, QDesktopWidget,
                            QLabel, QFileDialog, QWidget, QGridLayout, QMenu, QSizePolicy, QMessageBox, QWidget)
from PyQt5.QtGui import QIcon
from PyQt5.QtCore import QCoreApplication, Qt
from win32api import GetSystemMetrics

from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.figure import Figure
import matplotlib.pyplot as plt

import numpy as np

import random

CURRENT_VERSION = 0.1

class Example(QMainWindow):

    def __init__(self):
        super().__init__()

        self.initUI()

    def initUI(self):
        self.setWindowTitle('test')

        window_width = GetSystemMetrics(0)
        window_height = GetSystemMetrics(1)

        self.resize(0.6 * window_width, 0.6 * window_height)
        self.center()

        self.setWindowIcon(QIcon('Icon.png'))

        #inits
        self.openDirectoryDialog = ""
        self.data = np.empty(shape=(1,2), dtype=np.float)

        #Exit on menubar
        exitAct = QAction('&Exit', self)
        exitAct.setShortcut('Ctrl+Q')
        exitAct.setStatusTip('Exit applicatiion')
        exitAct.triggered.connect(qApp.quit)

        #Open on menubar
        openAct = QAction('&Open', self)
        openAct.setShortcut('Ctrl+O')
        openAct.setStatusTip('Open Directory')
        openAct.triggered.connect(self.openFile)

        #menubar
        menubar = self.menuBar()
        fileMenu = menubar.addMenu('&File')
        fileMenu.addAction(exitAct)
        fileMenu.addAction(openAct)

        #Central
        centralwidget = QWidget(self)
        self.setCentralWidget(centralwidget)

        #Grid
        grid = QGridLayout(centralwidget)
        self.setLayout(grid)

        #Plot
        plotCan = PlotCanvas(self, width=5, height=4)
        grid.addWidget(plotCan , 0,1)

        #button
        btn = QPushButton("Load Data", centralwidget)
        btn.resize(btn.sizeHint())
        grid.addWidget(btn, 0,0)

        btn.clicked.connect(plotCan .plot(self.data))

        self.show()

    def center(self):
        qr = self.frameGeometry()
        cp = QDesktopWidget().availableGeometry().center()
        qr.moveCenter(cp)
        self.move(qr.topLeft())

    def openFile(self):
        self.csvFile = QFileDialog.getOpenFileName(self, "Get Dir Path")[0]
        self.data = np.loadtxt(self.csvFile, delimiter=',', dtype='S')[2:].astype(np.float)

    def buttonpress(self):
        self.plot(self.data)

class PlotCanvas(FigureCanvas):

    def __init__(self, parent=None, width=5, height=4, dpi=100):
        fig = Figure(figsize=(width, height), dpi=dpi)
        self.axes = fig.add_subplot(111)

        FigureCanvas.__init__(self, fig)
        self.setParent(parent)

        FigureCanvas.setSizePolicy(self,
                QSizePolicy.Expanding,
                QSizePolicy.Expanding)
        FigureCanvas.updateGeometry(self)

    def plot(self, data = np.empty(shape=(1,2))):
        ax = self.figure.add_subplot(111)
        ax.plot(data[:,0],data[:,1], 'r-')
        ax.set_title('PyQt Matplotlib Example')
        self.draw()

if __name__ == '__main__':

    app = QApplication(sys.argv)
    w = Example()
    sys.exit(app.exec_())

在OpenFile我有一个非常具体的案例，我稍后会概括，但我使用的是CSV文件，前两行是标题。目前，当我启动程序时，我收到错误

Traceback (most recent call last):
  File "Plotter.py", line 115, in <module>
    w = Example()
  File "Plotter.py", line 23, in __init__
    self.initUI()
  File "Plotter.py", line 75, in initUI
    btn.clicked.connect(plotCav.plot(self.data))
TypeError: argument 1 has unexpected type 'NoneType'

我不明白，因为我已经初始化了数据。

Answer 1

QObject.connect()函数需要一个可调用的参数。在编写btn.clicked.connect(plotCan.plot(self.data))时，您将调用的结果传递给plotCan.plot(self.data)（默认为None，因为未指定return），因此您收到的错误消息

由于您希望将self.data变量与调用一起传递，因此一种简单的方法是使用lambda

btn.clicked.connect(lambda: plotCan.plot(self.data))

这满足connect()功能，并将调用推迟到plotCan.plot()

在PyQt5中使用Matplotlib绘制CSV文件

1 个答案: