Introduction to Python III

Text Editor

Geany
sudo apt-get install geany
Open geany and then open a .py file you've created before in this class
Build > Set Build Commands
- Compile command: python3 -m py_compile "%f"
- Execute command: python3 "%f"
Execute your Python scripts with F5

Review

Conditional statements
Loops
Blocks of code
Input

Review Exercise

If you have $100 saved in your bank account, and they pay you 3% interest every year, how much money will you have for each year, up to 10 years?

Hint: Use a for-loop. Don't forget to add the interest to the total

Functions

Functions allow you to write code just once, then reuse that code in your programs multiple times
Functions take in parameters, which is a variable you give it that is only available in the body of the function (the block of code inside of it)

def function(parameter):
    # block of code

Example of a Function

def printName(name):
       print("Hello, %s!" % name)

You define (make) the function like this:

And call it like this:

printName("John")

Which will return:

Hello, John!

Remember input()?

Example of a Function

def savings(chores, paper, spending):
    return chores + paper - spending
    # or return(chores +paper - sending)

Another example, except with return() instead of print:

And call it like this:

print(savings(10, 10, 5))

Which will return:

What does return() do? What's the different between return() and print()?

# comments the code

Scope

Not all variables are accessible from all parts of our program.
Where a variable is accessible depends on how it is defined.
We call the part of a program where a variable is accessible its scope.
A variable which is defined in the main body of a file is called a global variable.
- It will be visible throughout the file, and also inside any file which imports that file.
A variable which is defined inside a function is local to that function.
- It is accessible from the point at which it is defined until the end of the function

# This is a global variable
a = 0

if a == 0:
    # This is still a global variable
    b = 1

def my_function(c):
    # this is a local variable
    d = 3
    print(c)
    print(d)

# Now we call the function, passing the value 7
# as the first and only parameter
my_function(7)

# a and b still exist
print(a)
print(b)

# c and d don't exist anymore -- these statements
# will give us name errors!
print(c)
print(d)

SSH

Remotely access your Pis with Secure Shell
On your Pi: ifconfig
- Look for the IPv4 (inet) address uner eth0
On your laptop: ssh pi@IP
Type in your password
- First 3 letters of Pi name reversed, pi183
- The first letter of your pi name is capitalized in the password
  - ex Pi name: awesomepi
  - Password: ewApi183