Getting Started with PyCharm

PyCharm can be installed from here.

This tutorial assumes you are familiar with the process of building Mantid (with separate source and build directories inside a root directory), and that you have built a working version. If you are unclear about this see here.

Setting up PyCharm on Windows

PyCharm should be opened using pycharm.bat which can be found in the build directory (this sets some additional environment variables compared with simply opening PyCharm directly).

  1. Once PyCharm is open, set up the project. Go to File->Open and select the root directory in which both your source and build directories reside.

    Go to File->Settings, then under Project you will set two sub-menus Project Interpreter and Project Structure. The interpreter defines the python executable that will be used to run your code, and the structure menu allows you to decide which folders within the project to include and index.

  2. In the Project Interpreter sub menu, at the top select the options button and click Add..., a new window should appear titled “Add Python Interpreter”. In the menu on the left, select “System Interpreter” (a version of Python with all the correct variables set already exists within Mantid). Click on the ... to open a file browser, and navigate to;

    <Mantid Source Directory>/external/src/ThirdParty/lib/python2.7/python.exe

    This is the interpreter, so select “Ok” and apply the changes. This should bring up a list of all the packages associated to the interpreter. There should be many packages, however you should not see PyQt (but instead QtPy).

  3. In the Project Structure sub menu you should see your root directory with the source/build directories both visible (if not, add them). The folder structure should be present in the centre of the window allowing you to mark folders orange (excluded) or blue (source). Source directories will be searched for python code.

    Within the source directory add the following to your sources;

    <Mantid Source Directory>/scripts
    <Mantid Source Directory>/external/src/ThirdParty/lib

    The first folder can be replaced with the folder that contains your code, if you aren’t writing code in scripts/. In the Mantid build directory add the following as source folders;

    <Mantid Build Directory>/bin/Debug

    here we are setting up PyCharm for the Debug build, you would use /bin/Release instead if you are building mantid in release mode.

NOTE : In some cases, imports in the code will still be highlighted red when they come from folders within the script/ folder, or from other folders entirely. To fix this simply add the relevant folder that contains the module you are importing in the same fashion as step 3 above.

Running Files in the Debugger

Running python code from within PyCharm which depends on the python API, or PyQt for example requires one extra step. Because the source root labelling from the previous section only affects PyCharm searching and not the run configuration, before running the file we must set up the run configuration correctly.

As an example, create a new file in <Mantid Source Directory>/scripts/ called Copy into it the Python code below.

  1. To edit the configurations go to Run->Run... and select Edit Configurations. This should open up a sub window. Hit the green + in the top left to create a new configuration and name it. In order to tell PyCharm where to look for python modules and libraries we need to add some folders to the PATH environment variable. Click on the ... next to the Environment Variables box, and hit the + icon. In the Name column enter “PATH”, in the value column enter the following;

    <Mantid Build Directory>\bin\Debug;
    <Mantid Source Directory>\external\src\ThirdParty\bin;
    <Mantid Source Directory>\external\src\ThirdParty\lib\qt4\bin;
    <Mantid Source Directory>\external\src\ThirdParty\lib\qt5\bin;

    The semi-colon delimited list of paths should end in ;%PATH% so that we prepend to the existing list of paths rather than overwriting them. The last two lines will allow imports of PyQt4 and PyQt5 modules.

You should now be able to run and debug the scripts using the newly created configuration, by adding the full path of the file in the Script path box at the top of the configuration window.

Testing using PyQt

To test that the above instructions have worked, you can simply create a new Python file with the following content (for PyQt5)

# Check that PyQt imports
from qtpy import QtCore, QtGui, QtWidgets
# Check that the Mantid python API imports
import mantid.simpleapi

class DummyView(QtWidgets.QWidget):

    def __init__(self, name, parent=None):
        super(DummyView, self).__init__(parent)
        self.grid = QtWidgets.QGridLayout(self)
        btn = QtWidgets.QPushButton(name, self)

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    ui = DummyView("Hello")

Setting up PyCharm on Linux

On Linux the instructions are identical to Windows except that :

  • In step 1, the file is rather than pycharm.bat
  • In step 2, use the native python interpreter (/usr/bin/python2.7/python.exe) rather than from <Mantid Source Directory>/external/src/ThirdParty/lib/python2.7/python.exe
  • In step 4, add <Mantid Build Directory>/bin; to the PATH environment variable in the new configuration (rather than <Mantid Build Directory>/bin/Debug;), and remove the other three file paths.

Useful Plugins

You can install non-default plugins by pressing Ctrl+Alt+S to open the Settings/Preferences dialog and then going to Plugins. From here you can manage plugins, or add new ones by clicking Browse repositories.

The following non-default plugins are things our team has found useful for Mantid development:

  • Markdown support - Side by side rendering of markdown documents such as``.md`` , .rst (requires Graphviz to show graphs in preview)
  • dotplugin - Syntax highlighting for DOT
  • BashSupport - Syntax highlighting for BASH scripts
  • CMD Support - Syntax highlighting for .BAT ~scripts

Please add to this list if you find a useful plugin of your own