This document discusses Python variables, data types, and basic operations. It includes: 1) An introduction to variables and data types in Python, including integers, strings, and floats. 2) Details on assigning values to variables through assignment statements and how variables store copies of values. 3) An example program that takes a user-input number and performs a personality analysis based on that number. 4) A challenge to write a Fahrenheit to Celsius temperature converter program in Python.

1. Python 2
Variables, Assignment and
Types

2. Personality Tester
yournumber = input("Please enter a number between 1 and 99: ")
print "You entered " , yournumber
print "Performing personality analysis on your number choice …"
if yournumber < 49:
print "You are truly inadequate"
else:
print "You have delusions of grandeur"
print "That's all folks"

3. Values
• A basic thing – a letter or a number
• Values have TYPES
• Integers 1, 29485
• Strings “Hello world”
• Float – floating point 3.14159

4. Variables
• A variable has a value
mynumber

5. Variable names
• Can’t begin with a number
• Can’t contain spaces or other funnies
• Can’t be a keyword
– Type help() and press return
– Then type keywords in the box.

6. Assignment
Putting a Value ‘into’ a Variable
• myVariable = 23
• myLongVariable = “Hello how’s it going”
Sometimes written with an arrow
• myVariable 23
Assignment is really a sort of COPY
Why?

7. Assignment quiz
• What’s the value of myVariable
myVariable = 22
mySecondVariable = 13
myVariable = mySecondVariable
myVariable = str(myVariable)

8. Statements
• A statement is a piece of code that
Python can execute.
• Lots of statements make a script
• Scripts are the same as programs

9. Operators
• Operators ‘do things’ to operands
• The simplest operators are the math
+ addition 5+2
- subtraction 5-2
* multiplication 5*2
/ division 5/2
** exponentiation 5**2
% modulo 5%2
Now we can do the first part of the Python Challenge!

10. A useful program
• Write a Fahrenheit to Celsius converter
• The formula for the conversion is: F = 1.8 * C + 32
• To make this program work you will need to do the
following:
Get the user input using input(“your prompt here”)
Assign the result to a variable.
• That will give you a number, but it will be in a string type.
You’ll need to convert it to an integer type using
int(variablename).
• Now you have an integer, multiply it by 1.8 and add 32
• Print the result – your answer, to the screen with
print variablename

11. Challenge
• Write a script/program that allows you to
input two numbers and calculates their:
– Product
– Sum
– Difference
– Quotient (one number divided by the other
without any remainder)
– Remainder (remainder when one is divided by
the other)
– Exponent (one number to the power of the other)

12. Challenge 2
• Create an object
• Find its type
– Print (type(myobject))
• Find its id
– Print (id(myobject))
• What is that?