Split multiple strings into a list of objects in C#

Question

I have the following code:

public class Info
{
  public string Name;
  public string Num;
}

string s1 = "a,b";
string s2 = "1,2";

IEnumerable<Info> InfoSrc =
    from name in s1.Split(',')
    from num in s2.Split(',')
    select new Info()
    {
        Name = name,
        Num = num
    };

List<Info> listSrc = InfoSrc.ToList();

I would like my listSrc result to contain two Info items whose Name and Num properties are:

a, 1
b, 2

However, the code I show above results in four items:

a, 1
a, 2
b, 1
b, 2

will the splits always be the same length?

Johan
– Johan

2015-11-12 15:45:21 +00:00
Commented Nov 12, 2015 at 15:45 — Johan
– Johan, Commented Nov 12, 2015 at 15:45
Look into Enumerable.Zip.

Kvam
– Kvam

2015-11-12 15:48:04 +00:00
Commented Nov 12, 2015 at 15:48 — Kvam
– Kvam, Commented Nov 12, 2015 at 15:48

Tim Schmelter · Accepted Answer · 2015-11-12 17:07:21Z

6

You can use Enumerable.Zip:

IEnumerable<Info> InfoSrc = s1.Split(',')
    .Zip(s2.Split(','), (name, num) => new Info(){ Name = name, Num = num });

If you need to map more than two collections to properties you could chain multiple Zip together with an anonymous type holding the second and third:

IEnumerable<Info> InfoSrc = s1.Split(',')
    .Zip(s2.Split(',').Zip(s3.Split(','), (second, third) => new { second, third }),
        (first, x) => new Info { Name = first, Num = x.second, Prop3 = x.third });

Here is a hopefully more readable version:

var arrays = new List<string[]> { s1.Split(','), s2.Split(','), s3.Split(',') };
int minLength = arrays.Min(arr => arr.Length);  // to be safe, same behaviour as Zip
IEnumerable<Info> InfoSrc = Enumerable.Range(0, minLength)
 .Select(i => new Info
 {
     Name = arrays[0][i],
     Num = arrays[1][i],
     Prop3 = arrays[2][i]
 });

edited Nov 12, 2015 at 17:07

answered Nov 12, 2015 at 15:50

Tim Schmelter

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6 Comments

sab669 Over a year ago

Just to make sure I understand what's going on, basically you split s1 into an array of strings, then Zip that array with another array created from s2. This creates a collection of elements in accordance to whatever the third argument is-- which in this case is the constructor for the Info object. So basically you just get a collection of Info items?

Tim Schmelter Over a year ago

@sab669: yes, but not a collection. Currently it's just a query. If you want a collection you need to append ToList or ToArray. Enumerable.Zip enumerates two sequences simultaneously and returns the items which are at the same index.

user3716892 Over a year ago

What happens when I need three split strings of equal size? Info now has 3 fields. string s1 = "a,b"; string s2 = "1,2"; string s3 = "G,J";

sab669 Over a year ago

I more so meant collection is just the "generic" English term that you have a bunch of objects. But technically speaking, I guess I'm not 100% certain on the differences between the Collection / ICollection class + interface versus IEnumerable. Not sure when to use one or the other.

sab669 Over a year ago

@user3716892 You should just be able to zip InfoSrc and s3 together again and then assign that third property? I'm sure Tim has a better solution though. Zip says that the first and second arguments don't have to be of the same type so it shouldn't be an issue.

|

spender · Accepted Answer · 2015-11-12 15:52:56Z

5

Assuming that the number of items in each list is equal, it looks like you're trying to Zip them together...

s1.Split(',').Zip(s2.Split(','), (name, num) => new Info{Name = name, Num = num})

edited Nov 12, 2015 at 15:52

answered Nov 12, 2015 at 15:48

spender

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1 Comment

Amir Popovich Over a year ago

Should be: IEnumerable<Info> InfoSrc = s1.Split(',').Zip(s2.Split(','), (a, b) => new Info { Name = a, Num = b });

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