C#•2y ago

❔ Return groups of results using LINQ?

I'm iterating through a set of data with LINQ. The data's broken up into sections, where there's a "1" in the "NewSection" column on the first row of a new section, otherwise there's a "0" in that column. I want to make a function that returns an Enumerable of Enumerables of my data rows, where the inner enumerable is all the entries in each section. How would I construct my loop for this?

11 Replies

BenMcLeanOP•2y ago

The specific application is actually chapter and verse divisions in the text of a book. So there's a row for each verse, a "1" in the "IsABook" column at the start of each book, a "1" in the "IsAChapter" column at the start of each chapter, etc. Here's what I figured out:

public IEnumerable<IEnumerable<Row>> Chapters(IEnumerable<Row> book)
{
    bool first = true;
    List<Row> verses = new List<Row>();
    foreach (Row verse in book)
    {
        if (!first && verse.IsChapter())
        {
            yield return verses;
            verses.Clear();
        }
        verses.Add(verse);
        first = false;
    }
    yield return verses;
}

public IEnumerable<IEnumerable<Row>> Chapters(IEnumerable<Row> book)
{
    bool first = true;
    List<Row> verses = new List<Row>();
    foreach (Row verse in book)
    {
        if (!first && verse.IsChapter())
        {
            yield return verses;
            verses.Clear();
        }
        verses.Add(verse);
        first = false;
    }
    yield return verses;
}

Servator•2y ago

.GroupBy() maybe ?

BenMcLeanOP•2y ago

How would that work? I edited the code I think GroupBy would work if I had the name of each chapter or a chapter number in a column of my data, but not if I just have a "1" for the start of a new chapter

Servator•2y ago

let me write an example

Saber•2y ago

doubt groupby would work here

MODiX•2y ago

Samarichitane#3472

REPL Result: Success

var collection = Enumerable.Range(1, 10);

        var groups = collection.GroupBy(i => i % 2 == 0).ToList();

        var evens = groups.First(ints => ints.Key);
        var odds = groups.First(ints => !ints.Key);

        Console.WriteLine(string.Join(", ", evens));
        Console.WriteLine(string.Join(", ", odds));

var collection = Enumerable.Range(1, 10);

        var groups = collection.GroupBy(i => i % 2 == 0).ToList();

        var evens = groups.First(ints => ints.Key);
        var odds = groups.First(ints => !ints.Key);

        Console.WriteLine(string.Join(", ", evens));
        Console.WriteLine(string.Join(", ", odds));

Console Output

2, 4, 6, 8, 10
1, 3, 5, 7, 9

2, 4, 6, 8, 10
1, 3, 5, 7, 9

Compile: 605.878ms | Execution: 106.237ms | React with ❌ to remove this embed.

Saber•2y ago

lol

Servator•2y ago

Just pass chapter number there you go

BenMcLeanOP•2y ago

But my source data doesn't have chapter number, hence the question Yeah if I had the chapter number in a column, that would make this real easy I didn't make this and I'm trying to convert this data into something that's nicer for computers to read for the future.

Servator•2y ago

Still you can pass as a value tuple (IsABook, IsAChapter)

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Return groups of results using LINQ?