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[solved] Why doesn't Vector have Find? [message #45565]

Fri, 04 December 2015 14:59

cbpporter
Messages: 1427
Registered: September 2007

Ultimate Contributor

I know that it is not particularly fast, but it is convenient. I am tired of changing Vectors to Index for the sole reason of having uniform Find interface Smile

[Updated on: Tue, 03 January 2017 11:44]

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Re: Why doesn't Vector have Find? [message #45569 is a reply to message #45565]

Fri, 04 December 2015 19:43

Mindtraveller
Messages: 917
Registered: August 2007
Location: Russia, Moscow rgn.

Experienced Contributor

There is a common Find() template to achieve what you want. It is applied to a number of containers, not only Vector.
But I doubt if slow sequential search is a good idea at all. If you want Vector and you want to have quick search, make it sorted. Add items by using FindUpperBound()-like calls, then you may search with FindBinary() which costs O(log(n)), not O(n) as for sequential search.

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Re: Why doesn't Vector have Find? [message #45570 is a reply to message #45569]

Sat, 05 December 2015 11:28

mirek
Messages: 14257
Registered: November 2005

Ultimate Member

Mindtraveller wrote on Fri, 04 December 2015 19:43

There is a common Find() template to achieve what you want. It is applied to a number of containers, not only Vector.
But I doubt if slow sequential search is a good idea at all. If you want Vector and you want to have quick search, make it sorted. Add items by using FindUpperBound()-like calls, then you may search with FindBinary() which costs O(log(n)), not O(n) as for sequential search.

Actually, I think this might not be that bad idea, in fact I was thinking about it too.

Thing is that sometimes you know that you only have a limited number of elements to find, but you want to conserve memory. Index consumes quite a lot of auxiliary memory for hashing. In that case, I often use simple Vector with FindIndex. Anyway, sometimes later it is needed to convert (or copy/paste) code to Index. Having Find as method would save some typing.

BTW, if you are about to insert items by FindUpperBound, you might consider using Sorted* kind of container Smile

Mirek

[Updated on: Sat, 05 December 2015 11:46]

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Re: Why doesn't Vector have Find? [message #45989 is a reply to message #45570]

Wed, 10 February 2016 16:02

cbpporter
Messages: 1427
Registered: September 2007

Ultimate Contributor

So, has any decision been reached? Smile

I have a ton of finds in Vectors implemented using for loops and I'm about to replace them with my "find" global method.

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Re: Why doesn't Vector have Find? [message #45990 is a reply to message #45989]

Wed, 10 February 2016 18:07

mirek
Messages: 14257
Registered: November 2005

Ultimate Member

cbpporter wrote on Wed, 10 February 2016 16:02

So, has any decision been reached?

I have a ton of finds in Vectors implemented using for loops and I'm about to replace them with my "find" global method.

Well, FindIndex existed in U++ for ages... (does exactly that).

I am now in middle of major Core complete overhaul, changing everything to C++11/14 standards. Maybe I will add Find to Vector/Array in the process...

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Re: Why doesn't Vector have Find? [message #45999 is a reply to message #45990]

Fri, 12 February 2016 16:31

cbpporter
Messages: 1427
Registered: September 2007

Ultimate Contributor

FindIndex will do for now.

Hmmm, Core updates. Exciting!

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