Similar to sets, the dictionary data type in Python is a special data structure not commonly seen in other programming languages. In a dictionary, data is organized as key-value pairs. Values can be accessed using keys. Dictionaries are written inside curly braces.
# This program is an example of a dictionary in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
print(clothDict)
Result-
{'name': 'Shirt', 'size': 'Long', 'type': 'Casual'}Accessing a Specific Element
To access a specific value in a dictionary, you need the key.
# This program is an example of a dictionary in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
outputDict=clothDict["name"]
print(outputDict)
Result:
Shirt Similarly, to change a value, you use the key.
# This program is an example of a dictionary in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
clothDict["size"]="small"
print(clothDict)
Result:
{'type': 'Casual', 'size': 'small', 'name': 'Shirt'} Looping Through a Dictionary
Using a loop, you can get all the keys in a dictionary.
# This program is an example of loop in a dictionary in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
for i in clothDict:
print(i)
Result:
name
type
sizeSince the key is obtained through the loop, the value can also be extracted in the same way as before.
# This program is an example of a loop in a dictionary in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
for i in clothDict:
print(clothDict[i])
Result:
Shirt
Casual
LongDictionary Methods
Dictionaries have several built-in methods. Let’s look at some of them (in alphabetical order).
clear()
The clear() method removes all items from the dictionary.
# This program is an example of dictionary clear() method in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
clothDict.clear() # Clear() classmethod
print(clothDict)
Result:
{}copy()
The copy() method copies the dictionary to another dictionary.
# This program is an example of dictionary copy() method in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
outputDict=clothDict.copy() # copy() classmethod
print(outputDict)
Result:
{'name': 'Shirt', 'type': 'Casual', 'size': 'Long'}del()
The del statement deletes a specific element from the dictionary.
# This program is an example of dictionary del() method in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
del clothDict["size"] # del() method
print(clothDict)
Result:
{'name': 'Shirt', 'type': 'Casual'}You can also use del to delete the entire dictionary.
# This program is an example of dictionary del() method in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
del clothDict # del() method
print(clothDict)
Result:
Traceback (most recent call last):
File "main.py", line 10, in <module>
print(clothDict)
NameError: name 'clothDict' is not definedget()
The get() method accesses a specific element in the dictionary.
# This program is an example of dictionary get() method in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
outputValue=clothDict.get("name") # get() classmethod
print(outputValue)
Result-
Shirtkeys()
The keys() method returns all the keys in the dictionary.
# This program is an example of dictionary keys() method in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
outputValue=clothDict.keys() # keys() classmethod
print(outputValue)
Result:
dict_keys(['type', 'size', 'name'])len()
The len() method returns the number of items in the dictionary.
# This program is an example of dictionary len() method in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
dictLength=len(clothDict) # len() method
print(dictLength)
Result:
3pop()
The pop() method removes a specific item from the dictionary and returns its value.
# This program is an example of the dictionary pop() method in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
outputValue=clothDict.pop("type") # pop() method
print(outputValue) # popped value
print(clothDict)
Result:
Casual
{'name': 'Shirt', 'size': 'Long'} popitem()
The popitem() method removes a random item from the dictionary and returns it.
# This program is an example of dictionary popitem() method in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
outputValue=clothDict.popitem() # popitem() method
print(outputValue) # popped value
print(clothDict)
Result:
('size', 'Long')
{'type': 'Casual', 'name': 'Shirt'}setdefault()
The setdefault() method sets a default value if the specified key does not exist.
# This program is an example of dictionary setdefault() method in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
outputValue=clothDict.setdefault("size","short") # setdefault() method
print(outputValue)
print(clothDict)
outputValue2=clothDict.setdefault("color","white") # setdefault() method
print(outputValue2)
print(clothDict)
Result:
Long
{'size': 'Long', 'type': 'Casual', 'name': 'Shirt'}
white
{'size': 'Long', 'color': 'white', 'type': 'Casual', 'name': 'Shirt'}update()
The update() method updates the dictionary with the specified key-value pairs.
# This program is an example of dictionary update() method in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
clothDict.update({"color":"white"}) # update() method
print(clothDict)
Result:
{'type': 'Casual', 'name': 'Shirt', 'color': 'white', 'size': 'Long'}values()
The values() method returns all the values in the dictionary.
# This program is an example of dictionary values() method in python
clothDict={"name":"Shirt",
"size":"Long",
"type":"Casual"
} # Defining a dict
outputDict=clothDict.values() # values() method
print(outputDict)
Result:
dict_values(['Long', 'Shirt', 'Casual'])