Dictionary Comprehension in Python

Problem

• Need to create a Python dictionary by pairing elements from two lists (keys and values).
• Unsure if list comprehension syntax can be used directly for dictionaries in Python.

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Solutions

• Correct way: Use dictionary comprehension:

d = {k: v for k, v in zip(keys, values)}

• Alternative: Use the built-in dict constructor with zip:

d = dict(zip(keys, values))

• List comprehension alone ([... for ... in ...]) creates a list, not a dict.

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Things to Consider

• Both lists (keys and values) should be the same length. Extra elements are ignored.
• If keys are not unique, later values will overwrite earlier ones.
• Works in all modern Python versions (3.x).

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Gotchas

• Don’t use list comprehension syntax ([...]) when you want a dictionary; use {k: v ...}.
• If lists differ in length, zip stops at the shortest.
• Duplicate keys in your list will silently overwrite values.

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Sources

• StackOverflow: Create a dictionary with comprehension
• Python Official Docs: Dictionary Comprehensions
• StackOverflow: How to create dictionary from two lists?
• Real Python: Python Dictionary Comprehension

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Further Investigation

• Explore dict comprehensions with conditions:

{k: v for k, v in zip(keys, values) if v is not None}

• Learn about dictionary methods: .get(), .items(), .update()
• Guide: More Python Dictionary Comprehension Examples

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TL;DR

• Use {k: v for k, v in zip(keys, values)} to create a dict from two lists in Python.