[Python] 복사(copy)

일차배열, 이차배열

⭐️내용 보충 예정⭐️

얕은 복사 = swallow copy
동일한 주소값을 공유하기 때문에 서로 영향을 줌

깊은 복사 = deep copy
주소값을 공유하지 않기 때문에 서로 영향을 주지 않음

🌿 일차 배열 (List)

---

✔️ =

N = [3, 2, 5, 7, 1, 9]

swallowN = N

>> id(N)        =  2165412876872
>> id(swallowN) =  2165412876872   

>> id(N[0])        =  140736790688080
>> id(swallowN[0]) =  140736790688080

N[0] = 'a'

>> N        =  ['a', 2, 5, 7, 1, 9]  
>> swallowN =  ['a', 2, 5, 7, 1, 9]  

>> id(N[0])        =  2165413244016  
>> id(swallowN[0]) =  2165413244016 

✔️ copy

N = [3, 2, 5, 7, 1, 9]

swallowN = N.copy()

>> id(N)        =  3152113914440
>> id(swallowN) =  3152113914952     

>> id(N[0])        =  140736790688080
>> id(swallowN[0]) =  140736790688080

N[0] = 'a'

>> N        =  ['a', 2, 5, 7, 1, 9]  
>> swallowN =  [3, 2, 5, 7, 1, 9] 

>> id(N[0])        =  3152114281584  
>> id(swallowN[0]) =  140736790688080

✔️ 슬라이싱[:]

N = [3, 2, 5, 7, 1, 9]

swallowN = N[:]

>> id(N)        =  2408926892552
>> id(swallowN) =  2408926893064     

>> id(N[0])        =  140736790688080
>> id(swallowN[0]) =  140736790688080

N[0] = 'a'

>> N        =  ['a', 2, 5, 7, 1, 9]  
>> swallowN =  [3, 2, 5, 7, 1, 9]   

>> id(N[0])        =  2408931781744  
>> id(swallowN[0]) =  140736790688080

✔️ deepcopy

import copy

N = [3, 2, 5, 7, 1, 9]

deepN = copy.deepcopy(N)

print("id(N)     = ", id(N))
print("id(deepN) = ", id(deepN))

>> id(N)     =  1814854491144
>> id(deepN) =  1814854491208

import copy

N = [3, 2, 5, 7, 1, 9]

deepN = copy.deepcopy(N)

print("id(N[0])     = ", id(N[0]))
print("id(deepN[0]) = ", id(deepN[0]))

>> id(N[0])     =  140736790688080 
>> id(deepN[0]) =  140736790688080  	# WHY? -> mutable immutable 별표 꽝

N[0] = 'a'

print("id(N[0])     = ", id(N[0]))
print("id(deepN[0]) = ", id(deepN[0]))

>> id(N[0])     =  2940193926256
>> id(deepN[0]) =  140736790688080

🌿 이차 배열 (List)

---

✔️ 이차배열 deepcopy

import copy

N = [[3, 2], [5, 7], [1, 9]]

N_deep = copy.deepcopy(N)

print("N      = ", id(N))
print("N_deep = ", id(N_deep))

>> N      =  1846881730056
>> N_deep =  1846882392392   

print("N[0]      = ", id(N[0]))
print("N_deep[0] = ", id(N_deep[0]))

>> N[0]      =  1846881729928
>> N_deep[0] =  1846882392840