Pyton 객체와 데이터 구조 기초

<Python Object and Data Structure Basics>

Test your knowledge.

** Answer the following questions **

Write (or just say out loud to yourself) a brief description of all the following Object Types and Data Structures we've learned about. You can edit the cell below by double clicking on it. Really this is just to test if you know the difference between these, so feel free to just think about it, since your answers are self-graded.

 

Numbers: 기본적으로 저장할 수 있는 숫자 정보에는 두 가지 유형이 있습니다.

○ Integers - Whole Numbers(정수)

○ Floating Point - Numbers with a decimal(부동 소수점)

Strings: 문자열은 글자를 대상으로 순서를 지니는 시퀀스를 말합니다.

Lists: 리스트(배열)은 객체를 대상으로 순서를 지니는 시퀀스를 말합니다. 리스트는 가변적 입니다. 그 말은, 리스트에 있는 항목을 바꿀 수 있다는 뜻입니다.

Tuples: 튜플은 리스트와 상당히 비슷한 객체를 대상으로 순서를 지니는 시퀀스이지만, 불가변적 입니다.

Dictionaries: 딕셔너리는 key-value pair입니다. 딕셔너리는 순서가 없습니다. 따로 정렬도 불가 합니다.

 

Numbers

Write an equation that uses multiplication, division, an exponent, addition, and subtraction that is equal to 100.25.

Hint: This is just to test your memory of the basic arithmetic commands, work backwards from 100.25

 

In [1]:

# Your answer is probably different
(60 + (10 ** 2) / 4 * 7) - 134.75

 

Out[1]:

100.25

Answer these 3 questions without typing code. Then type code to check your answer.

What is the value of the expression 4 * (6 + 5)

What is the value of the expression 4 * 6 + 5 

What is the value of the expression 4 + 6 * 5 

 

In [2]:

4 * (6 + 5)

 

Out[2]:

44

 

In [3]:

4 * 6 + 5 

 

Out[3]:

29

 

In [4]:

4 + 6 * 5 

 

Out[4]:

34

What is the type of the result of the expression 3 + 1.5 + 4?

Answer: Floating Point Number

What would you use to find a number’s square root, as well as its square?//숫자의 제곱근과 제곱을 구히려고 할때 무엇을 사용하겠습니까?

In [5]:

# Square root:
100 ** 0.5

 

Out[5]:

10.0

 

In [6]:

# Square:
10 ** 2

 

Out[6]:

100

Strings

Given the string 'hello' give an index command that returns 'e'. Enter your code in the cell below:

In [7]:

s = 'hello'
# Print out 'e' using indexing

s[1]

 

Out[7]:

'e'

Reverse the string 'hello' using slicing:

In [8]:

s ='hello'
# Reverse the string using slicing

s[::-1]

 

Out[8]:

'olleh'

Given the string 'hello', give two methods of producing the letter 'o' using indexing.

In [9]:

s ='hello'
# Print out the 'o'

# Method 1:

s[-1]

 

Out[9]:

'o'

 

In [10]:

# Method 2:

s[4]

 

Out[10]:

'o'

Lists

Build this list [0,0,0] two separate ways.

In [11]:

# Method 1:
[0]*3

 

Out[11]:

[0, 0, 0]

 

In [12]:

# Method 2:
list2 = [0,0,0]
list2

 

Out[12]:

[0, 0, 0]

Reassign 'hello' in this nested list to say 'goodbye' instead:

In [13]:

list3 = [1,2,[3,4,'hello']]

 

In [14]:

list3[2][2] = 'goodbye'

 

In [15]:

list3

 

Out[15]:

[1, 2, [3, 4, 'goodbye']]

Sort the list below:

In [16]:

list4 = [5,3,4,6,1]

 

In [17]:

# Method 1:
sorted(list4)

 

Out[17]:

[1, 3, 4, 5, 6]

 

In [18]:

# Method 2:
list4.sort()
list4

 

Out[18]:

[1, 3, 4, 5, 6]

Dictionaries

Using keys and indexing, grab the 'hello' from the following dictionaries:

In [19]:

d = {'simple_key':'hello'}
# Grab 'hello'

d['simple_key']

 

Out[19]:

'hello'

 

In [20]:

d = {'k1':{'k2':'hello'}}
# Grab 'hello'

d['k1']['k2']

 

Out[20]:

'hello'

 

In [21]:

# Getting a little tricker
d = {'k1':[{'nest_key':['this is deep',['hello']]}]}

 

In [22]:

# This was harder than I expected...
d['k1'][0]['nest_key'][1][0]

 

Out[22]:

'hello'

 

In [23]:

# This will be hard and annoying!
d = {'k1':[1,2,{'k2':['this is tricky',{'tough':[1,2,['hello']]}]}]}

 

In [24]:

# Phew!
d['k1'][2]['k2'][1]['tough'][2][0]

 

Out[24]:

'hello'

Can you sort a dictionary? Why or why not?// 딕셔너리는 정렬이 가능합니까?

Answer: No! Because normal dictionaries are mappings not a sequence.

// 아니요, 기본 딕셔너리는 맵핑으로 이루어져있습니다. 순서를 지닌 시퀀스가 아닙니다.

Tuples

What is the major difference between tuples and lists?// 튜플과 리스트의 차이점이 무엇인가요?

Tuples are immutable!// Tuple은 불변입니다.

How do you create a tuple?

In [25]:

t = (1,2,3)

Sets

What is unique about a set?

Answer: They don't allow for duplicate items! // Sets은 중복 항목을 허용하지 않습니다.

Use a set to find the unique values of the list below:

In [26]:

list5 = [1,2,2,33,4,4,11,22,3,3,2]

 

In [27]:

set(list5)

 

Out[27]:

{1, 2, 3, 4, 11, 22, 33}

Booleans

For the following quiz questions, we will get a preview of comparison operators. In the table below, a=3 and b=4.

OperatorDescriptionExample

==	If the values of two operands are equal, then the condition becomes true.	(a == b) is not true.
!=	If values of two operands are not equal, then condition becomes true.	(a != b) is true.
>	If the value of left operand is greater than the value of right operand, then condition becomes true.	(a > b) is not true.
<	If the value of left operand is less than the value of right operand, then condition becomes true.	(a < b) is true.
>=	If the value of left operand is greater than or equal to the value of right operand, then condition becomes true.	(a >= b) is not true.
<=	If the value of left operand is less than or equal to the value of right operand, then condition becomes true.	(a <= b) is true.

What will be the resulting Boolean of the following pieces of code (answer fist then check by typing it in!)

In [28]:

# Answer before running cell
2 > 3

 

Out[28]:

False

 

In [29]:

# Answer before running cell
3 <= 2

 

Out[29]:

False

 

In [30]:

# Answer before running cell
3 == 2.0

 

Out[30]:

False

 

In [31]:

# Answer before running cell
3.0 == 3

 

Out[31]:

True

 

In [32]:

# Answer before running cell
4**0.5 != 2

 

Out[32]:

False

Final Question: What is the boolean output of the cell block below?

In [33]:

# two nested lists
l_one = [1,2,[3,4]]
l_two = [1,2,{'k1':4}]

# True or False?
l_one[2][0] >= l_two[2]['k1']

 

Out[33]:

False