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No, I wrote a follow up message today, however the first message the one I am replying to seems to have been on a trip around the matrix 
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Here.
I'm mulling over an idea that requires merging multiple lists. At some point in their history, the lists diverge and I need to make sure that when they combine, lists contain all the items.
The sizes of the lists are in the thousands and are persisted. I just need to work out a way to merge them efficiently.
Ideas? Name for the concept?
veni bibi saltavi
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Nagy Vilmos wrote: The sizes of the lists are in the thousands and are persisted. I just need to work out a way to merge them efficiently.
Similar to a JOIN in SQL?
Bastard Programmer from Hell 
If you can't read my code, try converting it here[^]
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It's a join except at the end the merged list is shared. Makes sense?
L0 = 0, 1, 2
L1 = 1, 3, 4
L2 = 2, 5, 6
first two merge:
L0 = 0, 1, 2, 3, 4
L1 = 0, 1, 2, 3, 4
L2 = 2, 5, 6
Then L2 merges with L1:
L0 = 0, 1, 2, 3, 4
L1 = 0, 1, 2, 3, 4, 5, 6
L2 = 0, 1, 2, 3, 4, 5, 6
Sort of. At some point L0 will merge again and all will be happy.
I think.
veni bibi saltavi
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I have a similar hell, myself. The company is spinning off a subsidiary and employees are being transferred to the subsidiary. The management hierarchy, during the transition, is such that a manage in one 'company' may be managing employees from the other or both. There's also a third 'company' which, except for a list of employees, is still a mystery to me.
Meanwhile, people get privileges based upon their department and their group. If you picture these as Venn diagrams, they don't necessarily fully overlap - and the can cross over boundaries.
Spread across multiple locations.
Essentially, it's mapping an every changing number of many-to-many lists.
The obvious answer is, of course, a view that lets you find all of each employees relationships. A long list, each employee (by uid, for example) occurring many times, mapping them to an ever changing state.
The key to this is that the view, itself, needs to be modified as the management changes the rules and shuffles people about. Partly, it's manipulating/adding to UNION's - but also, how selections are made, and creating/destroying columns as nuances erupt.
It's a game of whack-a-mole, but, once in place - and one bites the bullet that the solution will break - the logic of the view (views?) does the deed without causing damage.
| Ravings en masse^ |
|---|
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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I like it when they reorganize the company. The managers are so busy creating chaos and fighting each other that they find no time to harass me.
I have lived with several Zen masters - all of them were cats.
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OT but sounds a lot like something I did a long time ago in uni using prolog, don't laugh but that is prolog's forte, figuring out complex relationships in "data webs" (i.e. more complicated than trees, think overlapping trees joined at arbitrary points).
,
I remember prolog as one of those things like stereograms (those hidden 3-d images) that you can stare at for hours with no clue what/how it does anything - suck at 0%, and then in an instant it just makes sense (really was 0% to 100% with no in-between). I can understand how prolog has a place in AI - but back in those old days it was mostly just a novelty.
I said twas long ago, wouldn't even know where to start.
Signature ready for installation. Please Reboot now.
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That's a great response to a question that should have been asked in another forum !
«While I complain of being able to see only a shadow of the past, I may be insensitive to reality as it is now, since I'm not at a stage of development where I'm capable of seeing it.» Claude Levi-Strauss (Tristes Tropiques, 1955)
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You could use a HashSet and feed it with each of your original list. Redundant items will be discarded if item is already present. You can even provide your own equality comparer.
If you want to check whether you caught all original items, you can call the IsSupersetOf(IEnumerable) method for all of original lists; it should return true for all of them.
"I'm neither for nor against, on the contrary." John Middle
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- No programming questions in the lounge, and that is what is being asked for despite the wording.
- Dump the data into a single list and select back only distinct items - the platform, tools, etc. are your choice.
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Tim Carmichael wrote: No programming questions in the lounge, and that is what is being asked for despite the wording.
That rule does not apply to members above a certain point level. 
There are two kinds of people in the world: those who can extrapolate from incomplete data.
There are only 10 types of people in the world, those who understand binary and those who don't.
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HappyFestivus wrote: That rule does not apply to members above a certain point level.
Wrong !
«While I complain of being able to see only a shadow of the past, I may be insensitive to reality as it is now, since I'm not at a stage of development where I'm capable of seeing it.» Claude Levi-Strauss (Tristes Tropiques, 1955)
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BillWoodruff wrote: Wrong !
He meant to say reputation, and no I don't mean the numerical thing in our profiles. I get away with lots of things that are supposedly against the rules. Nothing to do with Maunder twice leaving a drinking session before it had really even begun.
Michael Martin
Australia
"I controlled my laughter and simple said "No,I am very busy,so I can't write any code for you". The moment they heard this all the smiling face turned into a sad looking face and one of them farted. So I had to leave the place as soon as possible."
- Mr.Prakash One Fine Saturday. 24/04/2004
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Nagy Vilmos wrote: Name for the concept
Assuming no duplicates? So, what, "add distinct by"?
public static void AddRangeDistinctBy<T>(this List<T> target, IEnumerable<T> src, Func<T, T, bool> equalityComparer)
{
src.ForEach(item =>
{
if (target.None(q => equalityComparer(q, item)))
{
target.Add(item);
}
});
}
Inefficient and not thread safe but gets the job done.
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That's a great response to a question that should have been asked in another forum !
«While I complain of being able to see only a shadow of the past, I may be insensitive to reality as it is now, since I'm not at a stage of development where I'm capable of seeing it.» Claude Levi-Strauss (Tristes Tropiques, 1955)
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BillWoodruff wrote: That's a great response to a question that should have been asked in another forum !
We'll let it slide for Nagy. Heaven knows, I've gotten away with it.
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Marc Clifton wrote: We'll let it slide for Nagy
You walk on water, Nagy walks on air 
«While I complain of being able to see only a shadow of the past, I may be insensitive to reality as it is now, since I'm not at a stage of development where I'm capable of seeing it.» Claude Levi-Strauss (Tristes Tropiques, 1955)
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Quote: At some point in their history, the lists diverge
Make a list of divergent items. 
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Wouldn't this simply be a "Union"?
At least in SQL Server a union merges multiple result sets and filters out duplicate results (unless you use UNION ALL instead of just UNION).
I'd assume most frameworks employ a similiar concept (at the .Net Linq Method "Union" does this as well)
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What do you think the Algorithms, Linq, and QA, forums are for ?
«While I complain of being able to see only a shadow of the past, I may be insensitive to reality as it is now, since I'm not at a stage of development where I'm capable of seeing it.» Claude Levi-Strauss (Tristes Tropiques, 1955)
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[^]
Get me coffee and no one gets hurt!
modified 6-Dec-17 11:38am.
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When I saw the photo, I thought it was going to be an article about the evil effects on the body of bacon and gin.
| Ravings en masse^ |
|---|
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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I think the @Mycroft-Holmes has to be inside the message for him to get an email about your post mentioning him.
Michael Martin
Australia
"I controlled my laughter and simple said "No,I am very busy,so I can't write any code for you". The moment they heard this all the smiling face turned into a sad looking face and one of them farted. So I had to leave the place as soon as possible."
- Mr.Prakash One Fine Saturday. 24/04/2004
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Yah I know where the photo comes from, it is my official Google ID photo as well.
As for being PETA person of the year I can do without it. They are too militant for my taste.
I look forward to a bunch of spam on my google account from this.
Never underestimate the power of human stupidity
RAH
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Leaves a sign that you've died in The War. (6)
One morning I shot an elephant in my pajamas. How he got in my pajamas, I don't know.
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