That's not the problem at hand. Python is good for pseudocode. But not if you want to talk about cache misses because in the pseudocode written with higher level languages a lot of details on how memory is accessed are opaque.
Again, what would you suggest instead? If you can't guess that `list` is supposed to represent an array of consecutive elements, I have trouble thinking of a language that'll make that clear without being exceedingly verbose for no reason.
A bit later, in the article, you'll see that memory patterns in allocating the arrays have a role. A role that was hidden initially.
> Again, what would you suggest instead?
The answer is inside you. You have only to search for it.
Or, if you really want to extort me the obvious: any low level language (even not implementing every detail but calling imaginary functions whose name suggest what they are doing). This exercise will show you for instance that you'll have to immediately choose if to append_to_dynamic_array() or add_to_linked_list().
> This exercise will show you for instance that you'll have to immediately choose if to append_to_dynamic_array() or add_to_linked_list().
Linked lists, that's what you're worried about? `[...]` is not a linked list in Python, in fact I don't know any imperative language where it's something other than a dynamic array/vector. I can only assume someone who doesn't understand or intuit this is arguing in bad faith, especially when taking your attitude into account. What did I do to deserve being talked down to?
> any low level language
Like this?
std::vector<std::vector<element_t>> groups(n_groups);
for (auto&& element : elements) {
groups[element.group].push_back(std::move(element));
}
std::sort(elements.begin(), elements.end(), [](const auto& a, const auto& b) {
return a.group < b.group;
});
std::vector<std::vector<element_t>> groups;
for (auto group_elements : group_by(std::move(elements), [](const auto& element) {
return element.group;
})) {
groups.push_back(std::move(group_elements));
}
Is it worth it? If you don't know `list` is a dynamic array in Python, how will you know `std::vector` is a dynamic array in C++? Not to mention the syntax is terrible. C would be just as bad. Using Rust would get people angry about Rust evangelism. The only winning move is not to play.
// Create n empty arrays.
DynamicArray* groups[n_groups];
for (int i = 0; i < n_groups; i++) {
groups[i] = create_empty_array();
}
// For each element in elements[], append it to its group's array.
for (int i = 0; i < n_elements; i++) {
append_to_dynamic_array(groups[elements[i].group], elements[i].value);
}
antirez: You already got it wrong. You've got a double indirection, with `groups[i]` pointing to a heap-allocated instance of `DynamicArray`, which supposedly stores the actual heap pointer.
It's not about the language being low-level or high-level. It's about understanding the basics of memory layout. If the pseudocode being in Python is an obstacle for you, the problem is not in Python, but in your (lack of) intuition.
I wrote the first random semantic that came in mind, in the pseudocode in C above. The fact you believe it is not the right one is a proof that in C I can express the exact semantic, and in Python I can't (because everything is hidden inside how the Python interpreter can or can not implement a given thing).
So, modify my C code to match what you have in mind, if you wish. But the point is that low level code will specify in a much clearer way what's going on with memory, and in a piece of code that is about memory layout / access, that's a good idea. Otherwise I consider Python a good language for pseudocode. Just: not in this case.
Have a nice day, I'll stop replying since would be useless to continue. P.S. I didn't downvote you.
