How Can LINQ Be Used to Remove Duplicate Items from a List?

Efficiently Removing Duplicates from Lists with LINQ

Data lists often contain duplicate entries, causing complications in data processing and analysis, especially with large datasets or data from multiple sources. LINQ (Language Integrated Query) provides an elegant solution for eliminating these duplicates.

The Challenge:

Consider a list of items, each with properties like Id, Name, Code, and Price. Duplicates can easily arise:

<code>• Item1, IT00001, 0
• Item2, IT00002, 0
• Item3, IT00003, 0
• Item1, IT00001, 0
• Item3, IT00003, 0</code>

The LINQ Approach:

LINQ's GroupBy and Select methods offer a concise way to remove duplicates. The following code snippet demonstrates this:

<code class="language-csharp">var uniqueItems = items.GroupBy(x => x.Id).Select(y => y.First());</code>

Step-by-Step Explanation:

1. GroupBy(x => x.Id): This groups the items list based on the Id property. Items with the same Id are placed into the same group.
2. Select(y => y.First()): This selects the first item from each group. Because each group contains items with identical Id values, this effectively selects only one instance of each unique item.

This method efficiently generates a new list containing only unique items, simplifying subsequent data manipulation.

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