Getting started with Python

Transcription

1 Getting started with Python (i.e. installing and testing it) 2018 From original slides by Tony Cahill

2 What is Python? Python is a free computer language that was created in 1991 It has many add-ons (called packages) which enable it to do many tasks It needs a Python interpreter installed on your computer You will want an Integrated Development Environment (IDE) to make programming easier You will want a package manager to make installation easy

3 Helping software choices We will use an IDE called PyCharm We will also use a package manager called Anaconda Good news Anaconda comes with a Python interpreter This Anaconda Not this Anaconda

4 IMPORTANT Order of Installation FIRST install Anaconda (this also installs Python) THEN install PyCharm (If you do this in the opposite order, then PyCharm will not find the Python installation when it is installed, requiring more work to get it configured)

5 Getting Anaconda Go to Select your Operating System

6 Getting Anaconda And Download the Python 3.6 version Click the main Download button

7 Downloading and Running Different browsers work in different ways When you download, you might have the option to Run If so, go ahead and run it. Otherwise, you might need to Save the file that is downloaded, and then run it The file should be in your default Download directory

8 Installing Anaconda The default options should all work

9 Installing Anaconda Make sure you install for Just Me You can install for All Users but some might face some issues later

10 Installing Anaconda Also make sure that it installs to the root of your home folder This should be the default already selected

11 This is fine, everything is fine (You might not get this) Installing Anaconda

12 Installing Anaconda You can add Anaconda to the PATH if you want, but it's not necessary

13 Now wait It will take a while for the files to be extracted and installed. Finally, Anaconda should finish installing. Don t install Microsoft VSCode or anything you can skip the learn about etc. options. Now it s time to install the PyCharm IDE

14 Getting PyCharm Go to You might need to accept cookies Click on Download Now

15 Click on Community download button (Free, open source)

16 Run the downloaded file (it s called something like pycharm-community )

17 You ll see a Next button. Click it.

18 You may need to allow the program to make changes, and to allow it to run (if an antivirus program gives a warning). You will need to set the folder for installation. The default is fine. You can accept the standard options. Choose the correct bit launcher. And do create an association with.py

19 If you see this you re done. Click the Run box, and then press Finish

20 Setting up PyCharm will now start. Since this is the first time, you will have to configure it. You won t have any settings to import (so choose Do not import settings. You can stick with the defaults but you do have to choose the Dark Side or the Light Side. After you choose, click Skip Remaining and Set Defaults. You can choose whether you want to share data or not.

21 Writing a Python program Your next window will ask if you want to Create a new Python project or Open an existing one. You don t have any projects yet, so Create a New Project

22 New Project You need to name the project. Don t worry about Project Interpreter yet. Click Create

23 You should see this screen Close the tip window, and the Virtual Environment should be created

24 Setting the Interpreter Settings for New Projects For later in the course, we want to make sure Python is using a good interpreter. The easiest thing to do is make sure the Anaconda interpreter is being used in all projects. If you do this now, you should not have problems later. Go to the File menu, and select Settings for New Projects Then, select Project Interpreter

25 Selecting the Right Interpreter There should be a project interpreter listed there. If it is not the Anaconda interpreter (the Python interpreter in the location where you installed Anaconda), then there will be problems. First, see if the interpreter is listed when you use the dropdown box. If the Anaconda installation is available, select it, and hit OK. You will see processes at the bottom that are updating indices and updating skeletons at the bottom of the PyCharm window. Wait for them to finish. You should now have the correct interpreter for every new project you create If the Anaconda installation is not listed, then click on the gear button and select Add. (Continued on next slide)

26 Selecting the Right Interpreter At the left there will be several environment tabs. You should be able to look at one of the Base Interpreter link under Virtualenv Python version under Conda Environment Interpreter under System Interpreter Base Interpreter under Pipev Environment You should see the most recent Python version (3.6, which should have been installed with Anaconda) available from the dropdown menu. If not, you can click on the at the right to browse to the file location where Anaconda was installed. From there, you can select the python.exe file that is in the Anaconda directory. You can check Make available to all projects. Finally, click OK.

27 Opening a new Python file in your project Select the project root (whatever you named your project) to open the New File menu. Either rightclick and select New, or press Alt+Insert, or go to the File menu at the top and select New. This brings up the new file menu. Select Python File (note your options may look different than this.) Give your new Python file a name.

28 Writing Your project should now look something like this. In the test0002.py (or whatever you named it) window to the right, type what is shown here. (Ignore the lightbulb the interpreter placed it there) You will now need to wait until the indexing and updating skeletons processes are finished (there will be a small progress bar at the bottom of the PyCharm window).

29 Running Under the Run menu, you should see a Run option. Click it to run your code. Congratulations! You have written your first Python program! A window may pop up select the name of your Python File. Then, at the bottom of the IDE you should see this new window with your results.

30 Troubleshooting If you did not change the Settings for New Projects, or are in a project opened before you set those settings, then sometimes PyCharm will have difficulty finding the correct Python interpreter. This usually happens if you had a prior version of Python installed somewhere on your system, and it finds that version before finding the newer Anaconda installation. You will most likely notice this when trying to run the program to import numpy and import matplotlib. If that program does not run, and you get an error that the module is not found, then you may need to ensure you are using the correct Python interpreter for this project. Under the File menu, select Settings Under the Project area, select Project Interpreter Then, follow the instructions as above for Settings for New Projects