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POBuilding lists by selecting one item from each group of an IGrouping
 

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  1. POBuilding lists by selecting one item from each group of an IGrouping
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    <p>Lets say I have a list of movies with a set of start times</p> <pre><code>public class Show { public string Name { get; set; } public DateTime Start { get; set; } } </code></pre> <p>Movie 1 - 8:00<br> Movie 1 - 10:00<br> Movie 1 - 12:00<br> Movie 2 - 9:00<br> Movie 2 - 11:30<br> Movie 2 - 15:00<br> Movie 3 - 12:00<br> Movie 3 - 13:00</p> <p>I end up with a grouped list, with the name of the movie being the key. I want to take one time from each group and create a <code>List&lt;DateTime&gt;</code>.</p> <p>Now since there are 3 items with 8 times, I should have 18 different lists.</p> <p>8:00 - 9:00 - 12:00<br> 8:00 - 9:00 - 13:00<br> 10:00 - 9:00 - 12:00<br> etc.</p> <p>I tried just looping through the groups</p> <pre><code>foreach (var movie in movies) { foreach (var time in movie) { // Start looping through other groups and movies } } </code></pre> <p>Anyways, this is either a bad solution or I wasn't doing something right because I ended up with Lists of <code>List&lt;DateTime&gt;</code> and I had to start looping through those lists to build more lists by only taking one item from each... It was just horrible. A regular nested <code>foreach</code> won't work because then I end up with my 8:00 Movie 1 having all instances of Movie 2 &amp; 3, so I had to keep the lists separate and that just became too messy.</p> <p>Any suggestions of a better way to approach this?</p> <p><strong>Summary:</strong></p> <p>An easier way to understand it would be like this, you want to see 3 movies in a single day. You know which 3 you want to see, you don't know what times you want to see them at.</p> <p>I need a list that would present all the options. You can see this movie at this time, this one at this time...</p> <p>e.g. </p> <p>List 1 - Movie 1 - 8:00, Movie 2 - 9:00, Movie 3 - 12:00<br> List 2 - Movie 1 - 8:00, Movie 2 - 9:00, Movie 3 - 13:00<br> List 3 - Movie 1 - 8:00, Movie 2 - 11:30, Movie 3 - 12:00<br> etc.</p> <p>Order of the list does not matter.</p>
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    1. USBrandon
    1. USBrandon
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      1. VTModeratorReview
    1. COSo what is your end goal... a list of the first time of the showing for each movie? It sounds like you're making a much more complex query when you don't need to be.
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      1. USTejs
    2. COHow are you deciding which time to take from each grouping? Is it the first in the list? earliest? latest?
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      1. USAdam Flanagan
    3. CO@Adam, since I require every possible combination, it doesn't matter which gets taken. They all need to be included at some point. @Tejs, the goal is to show every possible combination of times from all movies.
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