How do you iterate through a list in a dictionary Python?

Iterate through list of dictionaries in Python

In this article, we will learn how to iterate through a list of dictionaries.

List of dictionaries in use:

[{‘Python’: ‘Machine Learning’, ‘R’: ‘Machine learning’},

{‘Python’: ‘Web development’, ‘Java Script’: ‘Web Development’, ‘HTML’: ‘Web Development’},

{‘C++’: ‘Game Development’, ‘Python’: ‘Game Development’}, {‘Java’: ‘App Development’, ‘Kotlin’: ‘App Development’}]

Iterate over a dictionary with list values using nested for loop

First, we will iterate over all the items (key-value pairs) of dictionary by applying a for loop over the sequence returned by items() function. As value field of a key-value pair can be a list, so we will check the type of value for each pair. If value is list then iterate over all its items using an another for loop and print it, otherwise just print the value. For example,

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Output:

We iterated over all the key value pairs of dictionary and if any value field from the pair is a list object, then we printed each item of that list too. In our case, except one key, all other keys had the list values. Therefore, for each pair, we first checked if the type of value is list or not. If it is list, then only iterated over all the values from list, otherwise printed the value only.

How to Iterate Through List of Dictionaries in Python

There are multiple ways to iterate through list of dictionaries in python.

Basically, you need to use a loop inside another loop. The outer loop, iterates through each dictionary, while the inner loop iterates through the individual elements of each dictionary. There are different ways to do this.

You can simply iterate over the range of length of list.

In the outer loop, we use range and length function to create a list that we can iterate through. We use the index value to get each dictionary. In the inner loop, we use key variable to iterate through the current dictionary.

Alternatively, you can lop using while loop with an index.

In the above code, we modify the outer loop to use while condition instead of for statement. We use len function to get the length of list of dictionaries and use the index counter to increment from 0 as long as it is less than the length of dictionary list.

You can also directly loop through the dictionary elements.

You can even use a shortcut that directly loops through the dict, without using len or range functions, in the outer loop. In the inner loop too, there is no need for any lookup.

If you don’t want to do any lookups, you can use the following method.

Finally, you can also use list comprehensions as shown below to loop through list of dictionaries.

In this article, we have looked at different ways to loop through list of dictionaries in Python. You can use any of them as per your requirement.

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Using Keys() Method

You can use the keys() method provided by the dictionary to iterate through the keys of the dictionary.

It returns an iterable of the keys available in the dictionary. Then using for loop, you can iterate through the keys as shown below.

Snippet

Output

Snippet 2

If you want to access the value of the key, then you can use the get() method to get the value of the specific key during each iteration as shown below.

Output

This is how you can iterate through the dictionary keys using for loop and the keys() method provided by the python dictionaries.

Using Values() Method

You can use the values() method provided by the dictionary to iterate through the values of the dictionary items.

It returns an iterable of the values of each item available in the dictionary. Then using for loop, you can iterate through the values as shown below.

Snippet

You’ll see the value of each item in the dictionary printed as below.

Output

Using this method will not give access to the dictionary keys() which is not necessary in most cases. This makes this method the fastest method to iterate through the dictionary.

This is how you can iterate through the dictionary values using for loop and the values() method provided by the python dictionaries.

Using Items() method

You can iterate through the dictionary items using the items() method provided by the python dictionary.

items() method returns a tuple of key-value pair during each iteration.

Then using for loop, you can iterate through the key-value pair and access both the keys and values in the same iteration as shown below.

Snippet

You’ll see the below output. Keys and values will be printed for each iteration and no additional access to the dictionary is necessary to fetch the value of the key.

Output

This is how you can access the items of the dictionary using for loop and the items() method provided by the dictionaries.

Examples Iterate list of dictionaries in Python

Simple example code.

Iterate over the indices of the range of the len of the list:

Using range() and len() funcitons.

Output:

Using while loop with an index counter:

Output:

1
3
5

Iterate over the elements in the list directly

Output:

1
3
5

List Comprehension

Iterations inside a list-comprehension or a generator and unpack them later:

Output: [1, 3, 5]

Source: stackoverflow.com

Do comment if you have any doubts and suggestions on this Python List dictionary topic.

Note: IDE:PyCharm2021.3 (Community Edition)

Windows 10

Python 3.10.1

AllPython Examplesare inPython3, so Maybe its different from python 2 or upgraded versions.

Degree in Computer Science and Engineer: App Developer and has multiple Programming languages experience. Enthusiasm for technology & like learning technical.

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Related

Python Loop Through a Dictionary

❮ Python Glossary

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:

for x in thisdict:
print(x)

Example

Print all values in the dictionary, one by one:

for x in thisdict:
print(thisdict[x])

Example

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

for x in thisdict.values():
print(x)

Example

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

for x, y in thisdict.items():
print(x, y)