I have a structure of arrays std::vecors (all same length), I want to sort them all by some key. Can I having a list of "old position -> new position" apply this transformation to all the vectors one vector at a time?

C++

I have a set of objects with an int field and I have problems sorting these objects according to the value of this field of int

Can you provide sample input and output?

something like this (there are extra arrays for index search, but they are just to show the idea of possible data that I can use) https://ideone.com/rVa9Lm

sort(soaExample.begin(), soaExample.end(), [&sortedIndexes](auto lhs, auto rhs) { return sortedIndexes[lhs.field] < sortedIndexes[rhs.field] } );

don't I need to create an iterator for that? 🤔

Oh, begin and and is for an vector you sort

Then I don't understand what you mean

Yes, I was not very clear, I will try to explain more detailed. I have N vectors, all the same length, filled with some data. Let's say it represents a particle system for a game, one vector contains positions of particles, another contain colors, third contains sizes That's how I can find data for the first particle size_t particleIdx = 0; Vector2D pos = soa.positions[particleIdx]; Color color = soa.colors[particleIdx]; float size = soa.sizes[particleIdx]; Now imagine that for some reason I want to sort all this struct (each array of the struct) in a way that the particles will be stored from the smallest to the largest. So in the resulting struct the vector sizes will be just sorted ascending, the other two vectors will have their elements in position corresponding to positions of items in this sizes vector. Let's say our smallest element in sizes was on position 8 previously, the new position after the sort is 0. Then in positions vector we will move the element that was on 8th position also to 0, and the same with colors vector.

generate a new vector with data from 0 to soa.sizes.size() - 1. std::sort with [](index1, index2) { return soa.sizes[index1] < soa.sizes[index2]; } then use the list of indices to sort your old vectors. i don't see a better way.

but how to use this list to sort other vectors?

should I use some non-standard sort in this case, or there's a way to make the sort to work with indexes?

but that will have a bunch of cache misses

instead of swapping contents of one vector, swap from all three

hello everyone please, share information or guide about, how to use hashtable in C. thank you!

hello everyone please, share information or guide about, how to use hashtable in C. thank you!

hello everyone please, share information or guide about, how to use hashtable in C. thank you!

Yes, I was not very clear, I will try to explain more detailed. I have N vectors, all the same length, filled with some data. Let's say it represents a particle system for a game, one vector contains positions of particles, another contain colors, third contains sizes That's how I can find data for the first particle size_t particleIdx = 0; Vector2D pos = soa.positions[particleIdx]; Color color = soa.colors[particleIdx]; float size = soa.sizes[particleIdx]; Now imagine that for some reason I want to sort all this struct (each array of the struct) in a way that the particles will be stored from the smallest to the largest. So in the resulting struct the vector sizes will be just sorted ascending, the other two vectors will have their elements in position corresponding to positions of items in this sizes vector. Let's say our smallest element in sizes was on position 8 previously, the new position after the sort is 0. Then in positions vector we will move the element that was on 8th position also to 0, and the same with colors vector.

hey i want to begin to learn python but i don't know were to begin can anyone help me

This is an example for C. https://medium.com/@bennettbuchanan/an-introduction-to-hash-tables-in-c-b83cbf2b4cf6

Hello How can i implement a function in c++ that reverse a vector containing unique_ptr<int> elements?

I want the function to work with non-copyable types

Didn’t work

hey i want to begin to learn python but i don't know were to begin can anyone help me

I think I figured it out https://ideone.com/giYvMx Swaps can be done all in one loop also. I have a gut feeling that it's too simple to be true, will test it on more data later UPD: found issues, improved the solution, now it looks more realistic: https://ideone.com/gmNFCB

I think Igor/vector-tuple point is far superior. it completes in 200instr; whereas, loops reorganized (I submitted, then removed loop check links) only optimized 100 or consolidated to 150max instr. Heavy vector looping will cause cpu exhausting..

I think Igor/vector-tuple point is far superior. it completes in 200instr; whereas, loops reorganized (I submitted, then removed loop check links) only optimized 100 or consolidated to 150max instr. Heavy vector looping will cause cpu exhausting..

Can you please resend the link, I can't find it

Just consolidate you loop as one; 4-in-1 you will see it’s reducing 100+ instr.. Significant change!!

It's not only about instructions, also data fetches. But I'll compare them on the real data to see which is better

For moves instead of swaps, it will definitely be better for big cases, but it will make it all more complex (not sure if I want to dive into that)

It's not only about instructions, also data fetches. But I'll compare them on the real data to see which is better

Is it a premature optimization you're talking about? ;)

I think I figured it out https://ideone.com/giYvMx Swaps can be done all in one loop also. I have a gut feeling that it's too simple to be true, will test it on more data later UPD: found issues, improved the solution, now it looks more realistic: https://ideone.com/gmNFCB

btw std::swap should be written as using std::swap; swap(a, b);

And what C++20 changed?

btw std::swap should be written as using std::swap; swap(a, b);

Why not std::swap ?

for acquire semantics, is it gonna invalidate all the cache in the cpu cache or only the interested parts?

a and b might have their own (faster) swap implementations not in std::

oh, i was wrong. C++20 just forbid specialisations of std::swap in namespace std

You mean incorporating barriers between keys & values? asm volatile.. @gameraccoon

You mean incorporating barriers between keys & values? asm volatile.. @gameraccoon

sorry, void MyFormForLab::on_pushButton_clicked() { QString text = ui->comboBox->currentText(); ui->label->setStyleSheet("background-color:" + text); } It changes my background of the label, how to change the color of the text, not background? if to write just "color:".... it doesn't work.

https://www.w3schools.com/csS/css_text.asp