Last Update: 2020-08-12
If you like to develop an EnMAP-Box application, or more general, a QGIS and Qt application, we recommend to use a state-of-the-art Integrated Development Environment (IDE) like PyCharm. It offers run-time debugging, code completion, spell-checking, syntax highlighting, SCM support, unit-testing and many other helpful things.
Furthermore, we recommend to install QGIS within a conda / anaconda environment. The installation is (almost) the same on macOS, windows or linux, it is much easier to install additional python packages and admin rights are not required, e.g. to update QGIS.
1. Have Git installed¶
If not, download and install Git from https://git-scm.com/downloads
Check if git is installed to your local shell, e.g. as:
C:\Windows\System32>git --version git version 2.26.0.windows.1
2. Clone this repository¶
Clone the EnMAP-Box repository (or a fork) to your local
cd my_repositories git clone https://bitbucket.org/hu-geomatics/enmap-box.git
Now you can use git pull to update your local copy of the EnMAP-Box repository:
cd my_repositories/enmap-box git pull
Replace the repo uri with that of your EnMAP-Box repo fork, if you like to provide code via pull requests.
3. Create a QGIS conda environment¶
Create a new conda environment qgis_stable and install qgis from the conda-forge channel
$>conda create -n qgis-stable -c conda-forge qgis
Activate the new environment
$>conda activate qgis_stable
Install other required packages, e.g. that listed in
(qgis_stable) $>conda install scikit-learn --channel=conda-forge (qgis_stable) $>conda install matplotlib --channel=conda-forge
Some python packages which are not available as conda package can be installed directly with pip.
(qgis_stable) $>pip install gitpython (qgis_stable) $>pip install git-lfs
Depending on the components and applications you like to use, it might be required to install more packages.
(qgis_stable) $>qgis (qgis_stable) $>designer (qgis_stable) $>assistant
If you are using macOS and calling qgis does not show any application window, it might be necessary to set:
This can be done permanently for the qgis_stable environment by:
`(qgis_stable) conda env config vars set QT_MAC_WANTS_LAYER=1`
Start python and check it’s version. It should be a Python >= 3.7. Calling
quit()will close the python interpreter and return you to the conda shell:
(qgis_stable) C:\>python Python 3.8.1 | packaged by conda-forge | (default, Jan 5 2020, 20:17:16) [MSC v.1916 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> quit() (qgis_stable) C:\>
4. Setup PyCharm¶
Start PyCharm and add my_repositories/enmap-box as new project via File > Open File or Project
If this is not already the case, tell PyCharm where to find your Git-executable. Open File > Settings > Version Control > Git to set Path to Git executable. Press Test to check the used Git version.
whereto return the path of a git-executable that is available in your DOS/Linux/macOS shell
(qgis_stable) C:\>where git C:\Users\geo_beja\AppData\Local\Programs\Git\cmd\git.exe
Switch to Project: enmap-box > Project Interpreter and add your conda qgis_stable python as project interpreter
Switch to Project Structure and add
<your conda installation>/envs/qgis_stable/Library/pythonas additional project content root.
<your conda installation>/envs/qgis_stable/QGIS.app/Contents/MacOS/../Resources/python
Right-click on the
pluginssubfolder and select Sources. Now the PyQGIS API is available to your Python installation.
The same way allows you to include other directories to your project’s PYTHONPATH, e.g. to make code available from other folder or repositories.
(Windows + macOS) set the QGIS_PREFIX_PATH variable
PyCharm and PyQGIS need the environmental variable
Typical paths are:
OS QGIS_PREFIX_PATH Windows <your conda installation>\envs\qgis_stable\Library Linux <your conda installation>/envs/qgis_stable/Library macOS <your conda installation>/envs/qgis_stable/QGIS.app/Contents/Resources
Open Run > Debug … > Edit Configurations and add the QGIS_PREFIX_PATH to the User environmental variables. This way PyCharm runs python files in a environment with QGIS_PREFIX_PATH defined.
Also define the Environment variables for the Python console. Go to File > Settings > Build, Execution, Deployment > Console > Python Console and add QGIS_PREFIX_PATH to the Environment variables.
You might also like to use the conda environment shell in your Pycharm terminal. Open Tools > Terminal and set the shell path to
cmd.exe "/K" <your conda installation>\Scripts\activate.bat qgis_stable
Test the Python environment
To check if the QGIS API is available, open a Python Console and import the QgsApplication object.
from qgis.core import QgsApplication QgsApplication.instance() is None
The output should return
True, as we have not initialized any QgsApplication.
Now check if we can use the EnMAP-Box API to start the EnMAP-Box
import enmapbox enmapbox.run()
This should initialize a new QgsApplication and start the EnMAP-Box. The outputs printed to the python shell should look like:
Application state: QGIS_PREFIX_PATH env var: D:\miniconda3\envs\qgis_stable\Library Prefix: D:\miniconda3\envs\qgis_stable\Library Plugin Path: D:\miniconda3\envs\qgis_stable\Library/plugins Package Data Path: D:\miniconda3\envs\qgis_stable\Library/. Active Theme Name: Active Theme Path: D:\miniconda3\envs\qgis_stable\Library/./resources/themes\\icons/ Default Theme Path: :/images/themes/default/ SVG Search Paths: D:\miniconda3\envs\qgis_stable\Library/./svg/ C:\Users\geo_beja\AppData\Local\Temp\QGIS-PythonTestConfigPathp1k7w_s_\profiles\default/svg/ User DB Path: D:\miniconda3\envs\qgis_stable\Library/./resources/qgis.db Auth DB Path: C:\Users\geo_beja\AppData\Local\Temp\QGIS-PythonTestConfigPathp1k7w_s_\profiles\default/qgis-auth.db
If the terminal environment was setup well, you can start the EnMAP-Box from the Terminal window as well by
(qgis_stable) ..\enmap-box>python enmapbox
The Qt company provides several tools to that help to create Qt applications and are useful for PyQt and PyQGIS users as well.
The Qt Assistant allows you to browse fast and offline through Qt help files (
*.qch). These files exists for
all Qt classes and the QGIS API. They can be generated event with Sphinx, which allows you to provide your
own source-code documentation as
.qch file as well.
Start the Qt Assistant, e.g. from your PyCharm terminal:
*.qch*files which contain:
Go to Preferences > Add and add the follwing
File Documentation qgis.qch qgis.core, qgis.gui qtcore.qch Qt5.QtCore qtgui.qch Qt5.QtGui qtwidgets.qch Qt5.QtWidgets
Now you can explore the Qt (
Q...) and QGIS (
The Qt Designer is a powerful tool to create GUI frontends by drawing, drag and drop.
Created GUI form files are saved in a XML file ending with
*.ui. These can be called from
python to automatically create the entire GUI backend, e.g. windows and buttons defined with the Qt Designer.
You can start the Qt Designer from your PyCharm terminal by:
Qt Creator is the one-in-all IDE to develop Qt C++ applications. It includes the functionality covered by Qt Assistant (here called Help) and Qt Designer (here called form designer) and helps to browse C++ code. It is the preferred tool to explore the QGIS C++ source code, for example if you like to better understand what it does behind the QGIS python API.
Qt and the Qt Creator are available at https://www.qt.io/download. Ensure to install the code documentation for the same Qt version used by QGIS.