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This article introduces the knowledge of "what are the common methods of python dictionaries". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

1. The concept of dictionary

Like a list, a dictionary is also a variable sequence, but unlike a list, it is an unordered variable sequence. The contents saved are stored in the form of key-value pairs (key:value). Each key-value of the dictionary is separated by a colon: separated, separated by each key-value pair, and the whole dictionary is contained in {}.

Dict = {key1:value1,key2:value2} 2. The main features of dictionaries

1: read by key rather than by index

2: a dictionary is an unordered collection of arbitrary objects

3: dictionaries are variable and can be nested at will

4: dictionary keys must be unique

5: the keys of the dictionary must be immutable

3. Three ways to create a dictionary # the first method dic1 = {'name':'hacker','age':'18'} # the second method dic2 = dict (name='hacker',age='18') # the third method dic3 = dict ([(' name','hacker'), ('age','18')]) 4. The common method of dictionary 1.clear ()

Define the clear () method to clear all elements in the dictionary (return empty dictionary). Give me a chestnut. Clear all elements in the car dictionary

Car = {"brand": "Porsche", "model": "911", "year": 1963} car.clear () print (car)

The running results are as follows:

{}

2.copy ()

Define the copy () method to return a copy of the dictionary (copy dictionary). Give me a chestnut. Copy car dictionary

Car = {"brand": "Porsche", "model": "911", "year": 1963} res = car.copy () print (res)

The running result is as follows

{'brand':' Porsche', 'model':' 911, 'year': 1963}

3.get ()

Define the get () method that returns the value of the specified key. Give me a chestnut. Use the get method to return the value of "model"

Car = {"brand": "Porsche", "model": "911", "year": 1963} x = car.get ("model") print (x)

The running results are as follows:

nine hundred and eleven

4.keys ()

Define all keys that return to the dictionary. Give me a chestnut. Returns all keys of the car dictionary

Car = {"brand": "Porsche", "model": "911", "year": 1963} res = car.keys () print (res)

The running results are as follows:

Dict_keys (['brand',' model', 'year'])

5.values ()

Define all the values that return the dictionary. Give me a chestnut. Returns all values of the car dictionary

Car = {"brand": "Porsche", "model": "911", "year": 1963} res = car.values () print (res)

The running results are as follows:

Dict_values (['Porsche',' 911, 1963]) 6.items ()

Define all key-value pairs that return to the dictionary. Give me a chestnut. Returns all key-value pairs of car dictionaries

Car = {"brand": "Porsche", "model": "911", "year": 1963} res = car.items () print (res)

The running results are as follows:

Dict_items ([('brand',' Porsche'), ('model',' 911'), ('year', 1963)])

7.del ()

Define delete dictionary elements? Give me a chestnut. Delete the key "model" of the car dictionary

Car = {"brand": "Porsche", "model": "911", "year": 1963} del car ["model"] print (car)

The running results are as follows:

{'brand':' Porsche', 'year': 1963}

8.zip ()

Define the zip () method to package the key values into a dictionary

Li1 = ["name", "age"] li2 = ["hacker", "18"] print (dict (zip (li1,li2)

The running results are as follows:

{'name':' hacker', 'age':' 18'}

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