Python-Practicals

Lab Practice - Implementation of Python Programs

We love Programming. Our aim with this course is to create a love for Programming.

⚡ Running A Python Program

Excellent, now you have all the tools required to run a Python program on the command line.

As an illustration, I will use my simple Python script export-kobo, which reads annotations and highlights from the database file of a Kobo eReader device (KoboReader.sqlite), and prints them on the prompt or exports them to an output file.

Step 1: Download The Source Code

First, download the source code of the Python program you want to run.

This usually implies downloading either a single Python source code file (with extension .py), or a ZIP file containing several Python source code files and other resource files that you need to uncompress somewhere on your disk.

The exact details depend on your Python program, hence be sure to carefully read its install documentation. You can download the prescribed files with your browser, and then copy/uncompress them using the Windows graphical file manager.

In our example, we download the raw file export-kobo.py from the GitHub repository.

Remember Safety Rule 3 ("copy your Python files into a separate folder")?

We put the downloaded export-kobo.py file in a new folder C:\export-kobo:

Note that we also copied the KoboReader.sqlite file (the input of our Python program) from our Kobo eReader to the same folder.

Step 2: Open A Command Prompt And cd There

Then, open a Command Prompt as explained above, and change the current working directory to the folder where you put your Python program source files.

In our example, cd C:\export-kobo:

A simpler alternative to using the cd command takes advantages of the Windows file explorer. Just navigate the file explorer to the folder where your Python code is:

and select the File > Open command prompt > Open command prompt menu:

you will get a new Command Prompt window, already located at the correct directory:

Step 3: Run The Python Program

At this point, we are ready to run our program.

Type python export-kobo.py KoboReader.sqlite --list and hit Enter/Return:

The Python interpreter will load our export-kobo.py program, and run it with arguments KoboReader.sqlite and --list.

Clearly, the semantics of the arguments vary from program to program, depending on what each program is supposed to do.

In our case, export-kobo.py will read the file whose name is passed as the first parameter (KoboReader.sqlite) and it will list (--list option) the titles of all the eBooks with annotations or highlights in the database.

If we specify different command arguments, for example python export-kobo.py KoboReader.sqlite --csv --output exported.csv, we will get a different behavior:

In particular, this second command exported all the information contained in the KoboReader.sqlite file into the newly created file named exported.csv in CSV format:

You must check the documentation of your Python program to know the semantics of its arguments.

Usually, if you run a Python program without arguments you will get a synopsis of the accepted arguments:

If a -h or --help argument is given, then a more verbose help message will be printed:

Congratulations, now you should be able to download and run a Python program on your own!

⚡ Lab Contents

• 1. Python program to swap two variables using third variable.
• 2. Write a python program to swap two numbers without using third variable.
• 3. Write a python program to read two numbers and find the sum of their cubes.
• 4. Write a python program to read three numbers and if any two variables are equal, print that number.
• 5. Write a python program to read three numbers and find the smallest among them.
• 6. Write a python program to read three numbers and print them in ascending order (without using sort function)
• 7. Write a python program to read radius of a circle and print the area.
• 8. Write a python program to read a number, if it is an even number, print the square of that number and if it is odd number print cube of that number.
• 9. Write a Python program to calculate the length of a string.
• 10. Write a Python program to count the number of characters (character frequency) in a string.
• 11. Write a Python script to add a key to a dictionary. Sample Dictionary : {0: 10, 1: 20} Expected Result : {0: 10, 1: 20, 2: 30}
• 12. Write a Python script to concatenate following dictionaries to create a new one. dic1={1:10, 2:20} dic2={3:30, 4:40} dic3={5:50,6:60} Expected Result : {1: 10, 2: 20, 3: 30, 4: 40, 5: 50, 6: 60}
• 13. Write a Python script to check if a given key already exists in a dictionary.
• 14. Write a Python script to generate and print a dictionary that contains a number (between 1 and n) in the form (x, x*x). Sample Dictionary ( n = 5) : Expected Output : {1: 1, 2: 4, 3: 9, 4: 16, 5: 25}.
• 15. Write a Python script to merge two Python dictionaries.
• 16. Write a recursive function to calculate the sum of numbers from 0 to 10.
• 17. Given a list slice it into 3 equal chunks and reverse each chunk . ''' Original list [11, 45, 8, 23, 14, 12, 78, 45, 89] Chunk 1 [11, 45, 8] After reversing it [8, 45, 11] Chunk 2 [23, 14, 12] After reversing it [12, 14, 23] Chunk 3 [78, 45, 89] After reversing it [89, 45, 78].
• 18. Write a Python script to display the various Date Time formats. ''' a) Current date and time b) Current year c) Month of year d) Week number of the year e) Weekday of the week f) Day of year g) Day of the month h) Day of week '''.
• 19. Write a Python program to read first n lines of a file.
• 20. Write a Python program to copy the contents of a file to another file.
• 21. Write a Python program to count the number of lines in a text file.

Usage

How do I run a Python script that I downloaded from GitHub? Download python installer from their official website here. After installing, open the folder where you have downloaded the script, press and hold shift and right click anywhere in the folder, in the popup there will be a option to open command prompt here (if you are using windows 8.1 or lower) or open powershell here (if you are using windows 10) click on it, a black window will appear, paste the below command in that where filename.py is name of the python file you have downloaded.

python filename.py

And now press enter. Voila your python script will now run.

A step-by-step guide on installing Python and using the Command Prompt for Windows

Interesting things to try

Make some changes in the code and observe the output.

Built by (A-Z)

• Shubham Sapkal

License

MIT © Realocity