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From: Peter Duniho on 22 Jan 2010 00:25
Family Tree Mike wrote:
> [...]
> foreach (string UniquePlace in centers.OrderBy(c => c.Place).Select(c =>
> c.Place).Distinct())
> {
> Console.WriteLine(UniquePlace);
>
> foreach (string UniqueCenterInPlace in centers.OrderBy(c =>
> c.Name).Where(c => (c.Place == UniquePlace)).Select(c => c.Name))
>
> Console.WriteLine("\t{0}", UniqueCenterInPlace);
> }

Personally, were I to use something like the above (for this particular
question, it's inefficient) I would put the sort at the end of the
expression. Why sort more data than you have to?
From: Peter Duniho on 22 Jan 2010 00:30
shapper wrote:
> That Group approach is really great. I am just using it. [...]

Grouping is the best approach given your problem statement. It
specifically arranges the data in exactly the way you need it in a
single pass, rather than requiring a nested level of iteration.

But, for future reference�if you do find yourself having some other need
for which the Enumerable.Distinct() method is best, note the overload
for that method that takes an IEqualityComparer<T> argument. That can
allow you to find elements that are distinct without losing the actual
element instance to a project via Select().

Frankly, the frequency such an approach is useful is probably pretty
low. But it's handy to know about, for when you do need it. :)

Pete
From: Peter Duniho on 22 Jan 2010 00:37
Let me try that again, this time without such awkward phrasing. Instead of:

Peter Duniho wrote:
> [...] That can
> allow you to find elements that are distinct without losing the actual
> element instance to a project via Select().

I prefer:

"That can allow you to find elements that are distinct according to some
specific criteria without losing the actual element instance to a
projection via Select()."
From: Family Tree Mike on 22 Jan 2010 08:16


"Peter Duniho" wrote:

> Family Tree Mike wrote:
> > [...]
> > foreach (string UniquePlace in centers.OrderBy(c => c.Place).Select(c =>
> > c.Place).Distinct())
> > {
> > Console.WriteLine(UniquePlace);
> >
> > foreach (string UniqueCenterInPlace in centers.OrderBy(c =>
> > c.Name).Where(c => (c.Place == UniquePlace)).Select(c => c.Name))
> >
> > Console.WriteLine("\t{0}", UniqueCenterInPlace);
> > }
>
> Personally, were I to use something like the above (for this particular
> question, it's inefficient) I would put the sort at the end of the
> expression. Why sort more data than you have to?
> .
>

Good point!

Mike
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