In Ubuntu 20.04 and later the commands to install the latest version of Sypder 3 are: sudo apt install python3-pip python3-pyqt5 python3-pyqt5.qtsvg python3-pyqt5.qtwebkit Sudo python3 -m pip install -upgrade spyder If for you want to install the latest version of Sypder 3 instead of the Ubuntu package maintainer's version in Ubuntu 18.04 and earlier, the commands to do so are as follows: sudo apt install python3-pip python3-pyqt4 python3-pyqt5 python3-pyqt5.qtsvg python3-pyqt5.qtwebkit Spyder is a free open-source Python development environment providing MATLAB-like features in a simple and lightweight application. Another approach that could work in some cases is adding a validation for a QApplication instance with the method instance().Spyder can be installed with the following commands: In the code above you can see that we make a function for the creation of the QApplication instance (to make it local and prevent it to get into the namespace of the kernel). Trying to remove that instance will probably cause your program to get stuck in a blocking while-loop, as suggested here, and using sys.exit() doesn't help since it's the same as trying to exit Python (and hence the IPython console). In other words, when you try to re-run your application, you already have a QApplication instance initialized. The most common problem when running a PyQt application multiple times inside Spyder is that a QApplication instance remains in the namespace of the IPython console kernel after the first run. Title = QLabel( "Hello World from PyQt", self)
QtCore import QSize class HelloWindow( QMainWindow): QtGui import QMainWindow, QLabel, QGridLayout, QWidget, QApplication from PyQt4.
Import sys from PyQt4 import QtCore from PyQt4.
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