How can I do the Ruby method "Flatten" Ruby Method in C#. This method flattens a jagged array into a single-dimensional array.
For example:
s = [ 1, 2, 3 ] #=> [1, 2, 3]
t = [ 4, 5, 6, [7, 8] ] #=> [4, 5, 6, [7, 8]]
a = [ s, t, 9, 10 ] #=> [[1, 2, 3], [4, 5, 6, [7, 8]], 9, 10]
a.flatten #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Recursive solution:
IEnumerable Flatten(IEnumerable array)
{
foreach(var item in array)
{
if(item is IEnumerable)
{
foreach(var subitem in Flatten((IEnumerable)item))
{
yield return subitem;
}
}
else
{
yield return item;
}
}
}
EDIT 1:
Jon explains in the comments why it cannot be a generic method, take a look!
EDIT 2:
Matt suggested making it an extension method. Here you go, just replace the first line with:
public static IEnumerable Flatten(this IEnumerable array)
and you can use it like this:
foreach(var item in myArray.Flatten()) { ... }
I would have responded in a comment, but I need more than 300 characters.
@Alexander's solution is awesome, but it runs into a problem with arrays of strings. Since string implements IEnumerable, I think it will end up returning each character in every string. You can use a generic parameter to tell it what kind of thing you are hoping to have returned in these cases, e.g.:
public static IEnumerable Flatten<T>(IEnumerable e)
{
if (e == null) yield break;
foreach (var item in e)
{
if (item is T)
yield return (T)item;
else if (item is IEnumerable)
{
foreach (var subitem in Flatten<T>((IEnumerable)item))
yield return subitem;
}
else
yield return item;
}
}
Couldn't you just use IEnumerable#SelectMany?
I would also agree that SelectMany does this.
var s = new[] { 1, 2, 3 };
var t = new[] { 4, 5, 6 };
var a = new[] { s, t, new[] {7, 8} };
a.SelectMany(e => e);
// IEnumerable<int> {1,2,3,4,5,6,7,8}
I normalized the array. s and t are arrays of int. a is an array of arrays. You don't have mixed arrays with int and arrays, like you can do in ruby.
But vice-versa. flatten is the ruby equivalent I was looking for SelectMany in C#
