Items in Subcategories

rubenreyes
Topic Author
Offline
Senior Member

11 years 9 months ago #39989 by rubenreyes

Items in Subcategories was created by rubenreyes

Hello

We are updating a template and we would like to display a category items, subcategories and items in the subcategories.

We can see that when we activate in the category options to display subcategory items they all get included in $this->items

So far we have been doing the following: cycle through the subcategories, and then on each subcategory cycle through all the items to see which one is assigned to it, with a code like this:

Code:

foreach ($this->categories as $subcat) {
	// some code to display subcategory info
	foreach($this->items as $item) {
		if($item->catid == $subcat->id) {
			// some code to display item
		}
	}
}

My question is: is there a more "elegant" way to do this without the several cycles? Perhaps having a list of items under each category (even if only the item id). We noticed that there is $this->categories[x]->assigneditems but it is always null.

Perhaps we need to do something so that "assigneditems" is populated? This will help not only with having a more efficient code, but will allow us to make decisions that are based on the number of items in the subcategory, specially when there are none.

Thank you

Ruben

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ggppdk
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Administrator

11 years 9 months ago #39992 by ggppdk

Replied by ggppdk on topic Items in Subcategories

Hello,
about your code it involves (usually small/very arrays)
it is

O(m*n)

(where m is the number of categories and n is the number of items)

the following code is
O(n+n) ==> O(n)

Code:

$cat_item_map = array();
foreach($this->items as $item) {
  $cat_item_map[$item->catid][] = $item;
}

foreach ($this->categories as $subcat) {
  foreach($cat_item_map[$subcat->id] as $item) {
    //... display item, or do something with it
  }
}

NOTE your original code and this code will skip items that their main category does not belong to the subcategories

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