CODEWITHSUNDEEP
c#linq
markpirvine
markpirvine

Reputation: 1592

Format Data using Linq

I have a data set something like this:

2,Black
2,Blue
2,Red
1,Small
1,Medium

I need to convert this into the following:

2_0
2_1
2_2
1_0
1_1

The LINQ query I have at the moment uses an index for the second number, however it doesn't reset to 0 when changing from 2_ to 1_. I've tried using a GroupBy, but I can't get the results I need - can anyone help?

Upvotes: 0

Views: 104

Answers (2)

Risky Martin
Risky Martin

Reputation: 2521

You can group by the number and use the version of Select() that provides the index:

var result = data.GroupBy(x => x.Number,
                          (key, g) => g.Select((_, i) => string.Format("{0}_{1}", key, i)))
                 .SelectMany(x => x);

Note that this might behave differently than you'd expect if the same numbers aren't contiguous: e.g, 2, 2, 2, 1, 1, 2, 2.

Upvotes: 1

Lee
Lee

Reputation: 144136

IEnumerable<string> output = input
    .GroupBy(i => i.Num)
    .SelectMany(grp => grp.Select((item, idx) => string.Format("{0}_{1}", grp.Key, idx)));

Upvotes: 3

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