YouTipPython3 Dictionary
# Python3.x Python3 Dictionary
A dictionary is another mutable container model that can store objects of any type.
Each key-value pair in a dictionary is separated by a colon `:`, each pair is separated by a comma `,`, and the entire dictionary is enclosed in curly braces `{}`. The format is as follows:
d = {key1 : value1, key2 : value2, key3 : value3 }
**Note:** `dict` is a keyword and built-in function in Python, so it is not recommended to name your variable **dict**.
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Keys must be unique, but values do not need to be.
Values can be of any data type, but keys must be immutable, such as strings or numbers.
A simple dictionary example:
tinydict = {'name': 'tutorial', 'likes': 123, 'url': 'www.'}
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You can also create a dictionary like this:
tinydict1 = { 'abc': 456 } tinydict2 = { 'abc': 123, 98.6: 37 }
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## Creating an Empty Dictionary
Use curly braces `{ }` to create an empty dictionary:
## Example
# Use curly braces {} to create an empty dictionary
emptyDict ={}
# Print the dictionary
print(emptyDict)
# Check the length of the dictionary
print("Length:",len(emptyDict))
# Check the type
print(type(emptyDict))
The output of the above example is:
{}Length: 0
Use the built-in function `dict()` to create a dictionary:
## Example
emptyDict =dict()
# Print the dictionary
print(emptyDict)
# Check the length of the dictionary
print("Length:",len(emptyDict))
# Check the type
print(type(emptyDict))
The output of the above example is:
{}Length: 0
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## Accessing Values in a Dictionary
Place the corresponding key inside square brackets, as shown in the following example:
## Example
#!/usr/bin/python3 tinydict = {'Name': 'Tutorial', 'Age': 7, 'Class': 'First'} print("tinydict['Name']: ", tinydict['Name'])print("tinydict['Age']: ", tinydict['Age'])
The output of the above example is:
tinydict['Name']: Tutorial tinydict['Age']: 7
If you try to access data using a key that does not exist in the dictionary, you will get an error like this:
## Example
#!/usr/bin/python3 tinydict = {'Name': 'Tutorial', 'Age': 7, 'Class': 'First'} print("tinydict['Alice']: ", tinydict['Alice'])
The output of the above example is:
Traceback (most recent call last): File "test.py", line 5, in print ("tinydict['Alice']: ", tinydict['Alice'])KeyError: 'Alice'
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## Modifying a Dictionary
You can add new content to a dictionary by adding new key/value pairs, or modify or delete existing key/value pairs, as shown in the following example:
## Example
#!/usr/bin/python3 tinydict = {'Name': 'Tutorial', 'Age': 7, 'Class': 'First'} tinydict['Age'] = 8# Update Age tinydict['School'] = ""# Add information print("tinydict['Age']: ", tinydict['Age'])print("tinydict['School']: ", tinydict['School'])
The output of the above example is: tinydict['Age']: 8 tinydict['School']:
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## Deleting Dictionary Elements
You can delete a single element or clear the entire dictionary. Clearing requires only one operation.
To explicitly delete a dictionary, use the `del` command, as shown in the following example:
## Example
#!/usr/bin/python3 tinydict = {'Name': 'Tutorial', 'Age': 7, 'Class': 'First'} del tinydict['Name']# Delete key 'Name'tinydict.clear()# Clear the dictionary del tinydict# Delete the dictionary print("tinydict['Age']: ", tinydict['Age'