Python Dictionary and Set Methods

about Dictionary and Set that Python bulit-in types

Dictionary

• methods

    d.values()
    d.keys()
    d.items()
  

• basic

    key in d # if key in d, return True
  
    list(d) # return d keys
  
    d[key] = value # set d[key] to value
  
    d.pop(key[,default]) #if default set, when key not in dic, return default
    d.popitem()
  
    setdefault(key[,default]) #if key return value, else return default
  
    for k,v in d.items(): 
  
  

• sort

    #sorted by key
    sorted(dic.keys()[,reverse = False]) #return keys list
    sorted(dic.items()) #return items list
  
    #vsorted by lambda
    sorted(dic.items(), key = lambda x:x[1])
  
    #sorted by key's length
    sorted(dic.items(), key = lamda x:len(x[0])
  

• defaultdict

    from collections import defaultdict
  
    dic = defaultdict(int)
  
    dic['a'] -> dic['a'] = 0
  

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Set

• methods

    set.add(x)
  
    set.remove(x)
    set.discard(x) #remove method is if not in x , return ValueError
  

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