day07-Python development based operation and maintenance (deep / shallow copy, Dictionary / set / related operations)

 

1. deep copy and shallow copy

 

 

# ### deep and shallow copy copy 
"" " 
A. 7 = 
B = A 
A =. 8 
Print (B) 

LST1 = [l, 2,3] 
lst2 = LST1 
lst1.append (. 4) 
Print (lst2) Day 
" " " 
# shallow copy of a copy of the same name modules in this method is also called copy 
# method 1 (recommended) 
" "" 
Import copy 
LST1 = [l, 2,3] 
lst2 = copy.copy (LST1) 
lst1.append (. 4) 
Print ( lst2) 
"" " 
# method two 
# listing .copy 
LST1 = [l, 2,3 ] 
lst2 = lst1.copy () 
lst1.append ( . 5 )
 Print (LST1)
 Print (lst2) 

#Deep copy copy module has a method called DeepCopy 
"" " 
# shallow copy can copy all the elements in the list of one, two or more stages of elements can not be copied, so the lead deep copy 
lst1 = [1,2,3 , [4,5,6,7]] 
lst2 = lst1.copy () 
LST1 [-1] .append (. 7) 
Print (lst2) 
"" " 
Import Copy 
LST1 = [l, 2,3, [4,5 ,. 6 ]] 
lst2 = copy.deepcopy (LST1) 
LST1 [ -1] .append (. 9 )
 Print (lst2) 


# deep copy dictionary 
DIC1 = { " A " :. 1, " B " : [l, 2,3 ] } 
DIC2 = copy.deepcopy (DIC1) 
DIC1 [ " B " ].insert(2,4)
 Print (DIC2)
 Print (DIC1) 


# deep copy is larger than the space occupied by shallow copy, slower speed; 
# multistage deep copy container, a container with a shallow copy

Deep copy and shallow copy Sample Code

 

2. dictionaries correlation function

 

 

# ### 字典相关函数
dic = {}
# "top":"the shy","middle":"faker","bottom":"uzi","support":"rookie","jungle":"厂长"
# 增
dic["top"] = "the shy"
dic["middle"] = "faker"
dic["bottom"] = "uzi"
dic["support"] = "mata"
dic["jungle"] = "kakao"
Print (DIC) 

# fromkeys () using default values and a set of keys to create the dictionary (the initial value assigned to the current key is not recommended) 
LST = [ " Top " , " Middle " , " bottom " ] 
DIC = {} .fromkeys ( LST, None)
 Print (DIC) 

# attention point (list) 
LST = [ " Top " , " Middle " , " bottom " ] 
DIC = {} .fromkeys (LST, [])
 Print (DIC) 
DIC [ " Top " ] .append (. 1 )
Print (DIC) 

# puncturing 
DIC = { ' Top ' : ' The Shy ' , ' Middle ' : ' Simon ' , ' bottom ' : ' Uzi ' , ' Support ' : ' Mata ' , ' Jungle ' : ' Kakao ' }
 # POP () to delete the key to (if not the key to set the default value, error prevention) through key 
# RES = dic.pop ( "Middle") 
# Print (say)
# Print (RES) 

MyKey = " jungle123 " 
RES = dic.pop (MyKey, " the key does not exist " )
 Print (RES, dic) 

# popitem () to delete the last key-value pair 
RES = dic.popitem ()
 Print ( RES)
 Print (dic) 

# the Clear () clear the dictionary 
dic.clear ()
 Print (dic) 

# change 
# update () batch updates (there is the key to update, not the key is added) 
dic = { " LDB " : " Lu Tung-pin " , " LCH " : " blue and" , " TGL " : " Intuit deviation " , " ZGL " : " Zhang fruit old " , " xboyww " : " mysterious boy " } 
dicnew = { " HXG " : " Xiangu " , " xboyww " : " Wang " } 
dic.update (dicnew) 
Print (DIC) 

# check 
# GET () acquired by the key value (if the key can not set the default value,Error prevention) 
DIC = { "LDB " : " Lu Tung-pin " , " LCH " : " blue and " , " TGL " : " Intuit deviation " , " ZGL " : " Zhang fruit old " , " xboyww " : " mysterious boy " }
 # Print (dic [ "xboyww1111111"]) # normal if acquired, when the key is not given a direct 
Print (dic.get ( " xboyww1111111 " , "The key does not exist " )) #methods can get when this key does not exist, set a default value, no error 


DIC = { " LDB " : " Lu Dongbin " , " LCH " : " blue and " , " TGL " : " te deviation " , " ZGL " : " Zhang fruit old " , " xboyww " : " mysterious boy " }
 # keys () will form a new dictionary of key iterable 
RES = dic.
Keys () Print (RES) 

# values () values to form a new dictionary iterables 
res =dic.values ()
 Print (RES) 

# items () make up the keys of the dictionary for a tuple to form a new iteration may be subject 
RES = dic.items ()
 Print (RES)

Sample code correlation function Dictionary

 

 

 

 

 

Day07