IEnumerable.Select with index

Question

I have the following code:

 var accidents = text.Skip(NumberOfAccidentsLine + 1).Take(numberOfAccidentsInFile).ToArray();

where accidents is an array of strings.

I want to make a Linq transformation from the string array to an array of Accident objects as follows:

 return accidents.Select(t => new Accident() {Id = i, Name = t.Replace("\"", string.Empty)}).ToArray();

How do I retrieve the index i from the accidents array using Linq or do I have to go old school?

Do you want the index from the `accidents` array itself, or the index from the original `text` enumeration? If the former, then Marcin's answer is fine. If the latter, then you will need to do the `Skip()` and `Take()` _after_ the initial `Select()` where the index is introduced. — Peter Duniho, Dec 04 '14 at 02:12

score 24 · Accepted Answer · answered Dec 04 '14 at 02:08

24

I'm not sure what kind of index you're looking for, but if it's just set of consecutive numbers then you're lucky. There is Select overload that does exactly that:

return accidents.Select((t, i) => new Accident() {Id = i, Name = t.Replace("\"", string.Empty)}).ToArray();

It expects a delegate that takes two parameters - the item and its index.

answered Dec 04 '14 at 02:08

MarcinJuraszek

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Just a set of consecutive numbers is all I am looking for, thank you. – Klaus Nji Dec 04 '14 at 15:57

score 2 · Answer 2 · answered Dec 04 '14 at 02:25

2

Use Enumerable.Range to generate the ID values and then use the current value to index into your String Array:

Enumerable.Range(0, accidents.Length).Select(f => new Accident() { Id = f, Name = accidents[f] })

answered Dec 04 '14 at 02:25

Mike Burdick

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score 0 · Answer 3 · answered Dec 04 '14 at 03:39

May be this LINQ query will help you to find The formated name with Index:

var accidents=(from acc in accidents
    select new {
        id=accidents.IndexOf(acc),
        Name = acc.Replace("\"", string.Empty)
    }).ToArray()

or you can also use .ToList() for the case if you want result to be in IEnumerable format.

IEnumerable.Select with index

3 Answers3

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