Data, Variables, and Operators

CS 110

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Announcements

1. Keep an eye out for Tutorial Team assignments tomorrow afternoon
1. Reminder: Tutorial 1 is on Wednesday!
2. Make sure to watch the pre-recorded lecture BEFORE coming to class on Wed. In order to get attendance credit you need BOTH watch the video AND attend.
2. Office hours schedule available via Canvas this evening
3. Overview of this Week
1. Monday - Operators and Variables in Python
2. Wednesday - Functions in Python (Pre-Recorded - Out-of-Class MQ 1) + Tutorial 1
3. Friday - Writing our Own Functions + In-Class MQ 2
• Ex 1 - Due at 11:59pm on Canvas

A typical week…

Monday - Attend lecture, take a look at tutorial, and homework

Tuesday - Watch the pre-recorded lecture for Wednesday; peruse the tutorial

Wednesday - Come to the tutorial session, try your best to iron out all of your questions; see if you can do any of the HW

Thursday - by now, you should have a strong sense of how long it will take you to complete HW Exercise; if you need more time, apply for late penalty waiver

Friday - come to class, participate in MQ activities; finish up HW

Sat/Sun - take the weekend off

Resources available throughout the week: Canvas, Class, Office Hours, and edSTEM

Understanding the Words / Atoms of Programming

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Python is made up of different kinds of “words”, which can be used to construct sentences and paragraphs (statements and code blocks). Some types of ‘words’ in Python include:

• pieces of data like numbers, words, images, etc.
• operators are symbols that perform actions
• variables are containers that can hold data
• functions are blocks of code encased inside a function name
• reserved words (special words in python)
• modules

The first rule of programming!

Python will only do something you ask it to.

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Data Representation

How we represent pieces of data in Python

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two

2.0

Data Types

data come in different flavors we call data types

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two

2.0

2

two

2.0

Data Types

integer (int)

2

two

2.0

Data Types

integer (int)

2

"two"

2.0

Data Types

string (str)

integer (int)

2

"two"

2.0

Data Types

string (str)

float (float)

Variables

Named containers that allow us to store and access data in Python.

Variables

• Variables are named containers for storing and/or referencing data
• You assign values to variables using the assignment operator (equal sign)

variable_name = piece_of_data

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Variables

Turn the following statement into a sentence:

�favorite_cookie = "oreo"�

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Variables

Turn the following statement into a sentence:

�favorite_cookie = "oreo"�

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Variables

Turn the following statement into a sentence:

�favorite_cookie = "oreo"�

Assign the text "oreo" to a container called favorite_cookie.

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Variables

Turn the following statement into a sentence:

�favorite_cookie = "oreo"�

Assign the text "oreo" to a container called favorite_cookie.

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Big Idea: Our goal for any line of Python we write is to be able to explain what it does in plain english.

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Naming Variables

• Variable names in Python can be any length and can consist of:
• uppercase and lowercase letters (A-Z, a-z)
• digits (0-9)
• and the underscore character (_).
• The first character of a variable name cannot be a digit.

Example 1:

favorite_cookie = "oreo"

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Example 2:

1st_cookie = "oreo"

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Operators

Symbols that perform operations on inputs which we call operands.

Arithmetic Operators

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Example: Evaluate this expression (operator)

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4 * 6

operand

operand

operator

Example: Evaluate this expression (operator)

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4 * 6

4

operand

6

operand

*

operator

Example: Evaluate this expression (operator)

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4 * 6

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4

operand

6

operand

*

operator

Arithmetic Operators

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Operator Precedence

Python evaluates expressions as is done in mathematics. After precedence rules, expressions are evaluated left to right.

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Order of Operations

16 - 2 * 5 // 3 + 1

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Order of Operations

16 - 2 * 5 // 3 + 1

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Order of Operations

16 - 2 * 5 // 3 + 1

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10

16 - 10 // 3 + 1

�

Order of Operations

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16 - 10 // 3 + 1

�

Order of Operations

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16 - 10 // 3 + 1

�

Order of Operations

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3

16 - 3 + 1

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Order of Operations

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16 - 3 + 1

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Order of Operations

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16 - 3 + 1

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Order of Operations

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13

13 + 1

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Order of Operations

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14

�

Order of Operations

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Examples

Example 02_arithmetic_operators.py

String Operators

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