Python Dictionary

Dictionary is unordered,changable and indexed collection of items.

Create a Dictionary

In Python,dictionaries are written with curly brackets and they have keys and values pair.

Example

  thisdict={
 "brand":"Ford",
  "model":"Mustang",
  "year":1964
    
    }
 print(thisdict) 
 
 Output
 {'brand','Ford','model','Mustang','year','1964'}

Access Dictionary Elements

We can access the items of a dictionary by referring to its key name,inside square brackets.

Example

  thisdict={
        "brand":"Ford",
        "model":"Mustang",
        "year":1964
    
    }
    print(thisdict["model"])   
 
 Output
 {'brand','Ford','model','Mustang','year','1964'}

Loop through Dictionary

We can loop through the dictionary items by using a for loop.

When looping through dictionary the return values are the keys of dictionary,but there are methods to return the values as well.

Example

  thisdict={
        "brand":"Ford",
        "model":"Mustang",
        "year":1964
    
    }
    for x in thisdict:
        print(x)   
 
 Output
 {'brand','Ford','model','Mustang','year','1964'}

We can also use the values() function to return values of a dictionary.

Example

 thisdict={
        "brand":"Ford",
        "model":"Mustang",
        "year":1964
    
    }
    for x in thisdict.values():
        print(x)   
 
 Output
 {'brand','Ford','model','Mustang','year','1964'}

Loop through both keys and values using the items() function.

Example

   thisdict={
        "brand":"Ford",
        "model":"Mustang",
        "year":1964
    
    }
    for x,y in thisdict.values():
        print(x,y) 
 
 Output
 {'brand','Ford','model','Mustang','year','1964'}

Dictionary Length

To determine how many items a dictionary has, use the len() function.

Example

  thisdict={
         "brand":"Ford",
         "model":"Mustang",
         "year":1964
    
    }
   print(len(thisdict))
 
 Output
 {'brand','Ford','model','Mustang','year','1964'}

Add Items in Dictionary

To add an item to the dictionary,we use a new index key and assigning a value to it.

Example

   thisdict={
         "brand":"Ford",
         "model":"Mustang",
         "year":1964
    
    }
     thisdict["color"]="Red"
     print(thisdict)
 
 Output
 {'brand','Ford','model','Mustang','year':1964 ,'color':'red'}

Remove Items in Dictionary

The pop() method removes the item with the specified key name.

Example

    thisdict={
        "brand":"Ford",
        "model":"Mustang",
        "year":1964
    }
     thisdict.pop("model")
     print(thisdict)
 
 Output
 {'brand','Ford','year':1964}

The popitem() method removes the last inserted item.

Example

    thisdict={
        "brand":"Ford",
        "model":"Mustang",
        "year":1964
    }
     thisdict.popitem()
     print(thisdict)
 
 Output
 {'brand','Ford','model','Mustang'}

Dictionary Constructor

Using dict() constructor,we can make a set.

Example

    thisdict=dict(brand="Ford",model="Mustang",year=1964)
     print(thisdict)
 
 Output
 {'brand','Ford','model','Mustang','year:1964}