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• Dictionary Python For Loop
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Dictionary

A dictionary is a collection which is unordered, changeable and indexed. In Python dictionaries are written with curly brackets, and they have keys and values.

Example

Create and print a dictionary:

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Accessing Items

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

Example

Get the value of the 'model' key:

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There is also a method called get() that will give you the same result:

Example

Get the value of the 'model' key:

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Change Values

You can change the value of a specific item by referring to its key name:

Example

Change the 'year' to 2018:

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Loop Through a Dictionary

You can loop through a dictionary by using a for loop.

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

Example

Print all key names in the dictionary, one by one:

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Example

Print all values in the dictionary, one by one:

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Example

You can also use the values() function to return values of a dictionary:

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Example

Loop through both keys and values, by using the items() function:

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Check if Key Exists

To determine if a specified key is present in a dictionary use the in keyword:

Example

Check if 'model' is present in the dictionary:

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Dictionary Length

To determine how many items (key-value pairs) a dictionary has, use the len() method.

Example

Print the number of items in the dictionary:

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Adding Items

Adding an item to the dictionary is done by using a new index key and assigning a value to it:

Example

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Removing Items

There are several methods to remove items from a dictionary:

Example

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

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Example

The popitem() method removes the last inserted item (in versions before 3.7, a random item is removed instead):

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Example

The del keyword removes the item with the specified key name:

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Example

The del keyword can also delete the dictionary completely:

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Example

The clear() method empties the dictionary:

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Copy a Dictionary

You cannot copy a dictionary simply by typing dict2 = dict1, because: dict2 will only be a reference to dict1, and changes made in dict1 will automatically also be made in dict2.

There are ways to make a copy, one way is to use the built-in Dictionary method copy().

Example

Make a copy of a dictionary with the copy() method:

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Another way to make a copy is to use the built-in method dict().

Example

Python Dictionary For Loop Generate Keys In Word

Make a copy of a dictionary with the dict() method:

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Nested Dictionaries

A dictionary can also contain many dictionaries, this is called nested dictionaries.

Example

Dictionary Python For Loop

Create a dictionary that contain three dictionaries:

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Python Dictionary For Loop Generate Keys Pdf

Or, if you want to nest three dictionaries that already exists as dictionaries:

Example

Create three dictionaries, than create one dictionary that will contain the other three dictionaries:

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The dict() Constructor

It is also possible to use the dict() constructor to make a new dictionary:

Example

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Dictionary Methods

Python has a set of built-in methods that you can use on dictionaries.

Method	Description
clear()	Removes all the elements from the dictionary
copy()	Returns a copy of the dictionary
fromkeys()	Returns a dictionary with the specified keys and value
get()	Returns the value of the specified key
items()	Returns a list containing a tuple for each key value pair
keys()	Returns a list containing the dictionary's keys
pop()	Removes the element with the specified key
popitem()	Removes the last inserted key-value pair
setdefault()	Returns the value of the specified key. If the key does not exist: insert the key, with the specified value
update()	Updates the dictionary with the specified key-value pairs
values()	Returns a list of all the values in the dictionary