How to Extract Values from a Python Dictionary Using a List of Keys?

Retrieving Dictionary Values for a List of Keys

In Python, extracting corresponding values from a dictionary given a set of keys is a common task. This article explores a straightforward method to achieve this using list comprehension.

Question:

How can we leverage a list of keys to obtain the corresponding values from a dictionary as a new list?

Example:

Consider the following dictionary:

<code class="python">mydict = {'one': 1, 'two': 2, 'three': 3}</code>

And a list of keys:

<code class="python">mykeys = ['three', 'one']</code>

Our objective is to generate a list containing the values [3, 1].

Answer:

A concise and elegant way to accomplish this task is through list comprehension:

<code class="python">[mydict[x] for x in mykeys]</code>

The list comprehension iterates over the mykeys list and accesses the corresponding values in the dictionary mydict. The result is a new list containing the extracted values.

Explanation:

Each element in the list comprehension has the following structure:

<code class="python">mydict[x]</code>

Where x represents the current key from the mykeys list. This syntax retrieves the value associated with that key in the mydict dictionary.

By combining these values using list comprehension, we obtain a new list containing the desired values in the same order as the original mykeys list.

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