Data Science

Qualititative Data

Can be divided into different categories

Ex. What’s your favorite type of coffee?

Quantitative Data

Is a numerical data that can be counted or measured

Ex. How many cups of coffee did you drink today?

Variable

A name that stores a piece of data

Ex. greeting = “Hello, World!”

print(greeting)

Output: Hello, World!

var name = greeting

data type = string

value = “Hello, World!”

Naming Rules 

Basic Guidelines 

• Use descriptive names

• Underscores take the place of spaces

• Only lower case letters

• Cannot start with a number

Integer 

A number can be positive, negative or zero w/o a decimal component 

Ex. -5;  500; ;0

Float

A number can be positive, negative or zero w/ a decimal component

Ex. 3.2; 0.0; 4.5623 

String

Contains sequence of letters, numbers, punctuations, spaces, etc.

Ex.”abcdehj”; “Hello, World!”

Character

Contains single character or punctuation

Ex. a; z; 1; !; #;

Boolean

Binary and evaluate to either true or false

Ex. True or false

==

equal to → 6 == 6

!= / ≠

not equal to → 6 != 7

>

greater than → 6 > 7

<

less than → 6 < 7

>=

greater than or equal to → 6 >= 7

<=

less than or equal to → 6 <= 7

and

is only true if both conditions are true

Ex. 6 > 7 and 6 > 3

* Print false because 6 is not greater than 7, only one statement is true not both

or

is only true if either condition is true

Ex. 6 > 7 or 6 > 3

* Print true because 6 is greater than 3. One statement is true, doesn’t require both statements to be true 

not

negates the truth value of the condition

Ex. not (6 > 7)

* print true because 6 isn’t greater than seven, the statement is false

List

a collection of ordered items

Built in functions

Python modules

• Can be imported into your code

• Contains predefined functions, variables and more

• Helps build programs faster and w/ less difficulty

• A package is a collection of related modules

• A library is a collection of modules and packages

Series

One-dimensional labeled array or list that is formatted for like a single column of a data table. 

Mean

Use when points aren’t too spread out and there aren’t any outliers.

• Use to avoid outliers from negatively affecting data

Median

Use when there are extreme outliers or the data isn’t balanced well.

Mode

Use when there is only a few different data values 

Documentation

A written set of instructions for using the python module or library.

• Lists functions that are included

• Directs how to use each function

• Offers examples 

Measures of Spread

Indices

Assigns names to elements in the list 

Dataframe

A data structure that stores and aligns data in a table using rows and columns

• Essentially a collection of more than one series. 

table.dtypes

Lists the datatypes used in each column in the Data Frame. 

This one for examples print integers as a datatype because positive whole numbers are being used in the column.

table.shape

• Displays the # of rows and columns within the table

table.describe

• Lists and describes all the specific statistics for each column

the round command rounds the decimal to whatever place the user inputs in this case, the decimal is rounded to 1 place. 

Rows Commands

Determine which rows of the table are displayed, instead of displaying the entire table, useful for using big data tables. 

table.head / table.tail

displays the first or last few rows depending on which number is placed in the parentheses

* if there isn’t any number in the parentheses, the function will display the first / last five rows as a default.

table[a:b]

Choose a specific section of the table to display using brackets.

will list the rows using the indices from the first # to the last # EXCLUSIVELY

* Will not include the last #

Module

A python module:

• Can be imported into your code

• Contains predefined functions, variables, and more.

• helps to build programs faster with less difficulty.

Package

• A collection of related modules

Library

Is a collection of modules and packages that can be imported into a program