찾으시는 정보가 있으시다면
주제별reference를 이용하시거나
우측 상단에 있는 검색기능을 이용해주세요

Number

Int : or integer, is a whole number, positive or negative, without decimals, of unlimited length

Float : or “floating point number” is a number, positive or negative, containing one or more decimals

Can also be scientific numbers with an “e” to indicate the power of 10

Complex : Are written with a “j” as the imaginary part, Can’t convert into another number type

String

Can assign a multiline string to a var by using three quotes

In the result, the line breaks are inserted at the same position as in the code

a = “””
I
am
Spongebob
”””
print(a)
# output
“I
am
Spongebob”

In python are arrays of bytes representing Unicode characters

However, Python doesn’t have a character data type

A single character is simply a string with a length of 1

Square brackets can be used to access elements of the string

a = “Hello, World!”
print(a[0])	# output “H”
# To check if a certain phrase or character is present in a string, can use “in”
print(“Hello” in a)	#output True

Slicing

Can return a range of characters by using the slice syntax

Specify the start index and the end index, separated by a colon, to return a part of the string

a = “Hello, World!”
print(a[2:5])	# output “llo”
# By leaving out the start or end index, the ragne will start or end, at the first or end character
print(a[:5])	# output “Hello”
# Use negative indexes to start the slice from the end of the string
print(a[-1])	# output “!”

Modify

Python has a set of built-in methods that you can use on strings

a = “ Sponge, Bob ”
print(a.upper())	# output “ SPONGE, BOB ”
print(a.lower())	# output “ sponge, bob ”
print(a.strip())		# output “Sponge, Bob”
print(a.replace(“S”, “s”))	# output “ sponge, Bob ”
print(a.split(“,”))	# output [‘ Sponge’, ‘ Bob ’]

Format

In python, can’t combine strings and numbers using +

But can combine strings and numbers by using the format()

It takes the passed arguments, formats them, and places them in the string where the placeholders {} are

It takes unlimited number of arguments, and are placed into the respective placeholders

age = 20
txt = “I am {}”
print(txt.format(age))		# output “I am 20”

# Can use index numbers {0} to be sure the arguments are placed in the correct placeholders
quantity = 3
itemno = 567
price = 49.95
order = “I wanna pay {2} dollars for {0} pieces of item {1}”
print(order.format(quantity, itemno, price))

Escape

To insert characters that are illegal in a string, use an escape character

An escape character is a backslash \ followed by the character you want to insert

txt = “We are the so-called \“Vikings\” from the north”

\’ : Single quote

\ : Backslash

\n : New Line

\r : Carriage Return

\t : Tab

\b : Backspace

\f : Form Feed

\ooo : Octal value

\xhh : Hex value

Boolean

Represent one of two values : True or False

Can evaluate any expression in Python, and get one of two answers

# Can compare two values
print(10 > 9)	# output True
print(10 == 9)	# output False

Almost any value is evaluated to True if it has some sort of content

Any string is True, except empty strings

Any number is True, except 0

Any list, tuple, set, and dict are True, except empty ones

Collection

List : Is ordered and changeable, allows duplicate members

Tuple : Is ordered and unchangeable, allows duplicate members

Set : Is unordered, unchangeable(but can remove or add item), and unindexed, no duplicate members

Dictionary : Is ordered(In python 3.6 and earlier, unordered) and changeable, no duplicate members

List

Are used to store multiple items in a single var

Are created using square brackets

list = [“apple”, “banana”]

List items are indexed, the first item has index[0]

Are ordered, changeable, and allow duplicate values

Ordered means that the items have a defined order, and that order will not change

• If add new items to a list, the new items will be placed at the end of the list

Changeable means that can change, add, and remove items in a list after it has been created

Allow duplicate means that can have items with same value

Items can be of any data type, also list can contain different data types

Tuple

Are used to store multiple items in a single var

Are written with round brackets

tuple = (“apple”, “banana”)

Are ordered, unchangeable, and allow duplicate values

Tuple items are indexed, the first item has index[0]

Ordered means that the items have a defined order, and that order will not change

Unchangeable means that we can’t change, add or remove items after the tuple has been created

Since tuples are indexed, they can have items with the same value

To create a tuple with only one item, you have to add a comma after the item, otherwise Python will not recognize it as a tuple

Items can be of any data type, also tuple can contain different data types

Set

Are used to store multiple items in a single var

Are unordered, unchangeable, and unindexed, don’t allow duplicate values

• Set items are unchangeable, but can remove items and add new items

• Can’t be sure in which order the items will appear

Unordered means that the items in a set don’t have a defined order

Unchangeable means that can’t change the items after the set has been created

Are written with curly brackets

set = {“apple”, “banana”}

Dictionary

Are used to store data values in key:value pairs

Is ordered, changeable and don’t allow duplicates

Are written with curly brackets, and have keys and values

dict = {“brand”: “Ford”, “model” : “Mustang”}

Dict items are ordered, changeable, and doesn’t allow duplicates

Ordered means that the items have a defined order, and that order will not change

Changeable means that we can change, add or remove items after the dict has been created

The values in dict items can be of any data type