Breaking up List into sublists by multiple values

Question

I'm trying to break up a C# List<InventoryItem> into multiple lists based on two different values: InventoryItem.name and InventoryItem.isStackable.

I want the list to be broken up into multiple lists for the purpose of populating my UI with the data - while keeping non-stackable items in their own list (one item per item slot in UI terms.)

If this is the input:

{
   InventoryItem - name:apple,  stackable:true
   InventoryItem - name:apple,  stackable:true
   InventoryItem - name:carrot, stackable:true
   InventoryItem - name:knife,  stackable:false
   InventoryItem - name:knife,  stackable:false
 }

I should get this output:

{
   InventoryItem - name:apple, stackable:true
   InventoryItem - name:apple, stackable:true
 }
 {
   InventoryItem - name:carrot, stackable:true
 }
 {
   InventoryItem - name:knife, stackable:false
 }
 {
   InventoryItem - name:knife, stackable:false
 }

I'm successfully separating by name alone (see below), but I'm not sure how to take isStackable into account. I'm also using LINQ which I'd prefer to avoid if possible.

var itemsByType     = new List<List<InventoryItem>>();
var inventoryByItem = inventory.GroupBy(x => x.name);
foreach(var v in inventoryByItem)
{
    var itemList = v.ToList();
    itemsByType.Add(itemList);
}

Answer 1

I think a better aproach would be to store the quantity of an item, instead of storing the stackable itens repeatdly in a list. Because when we are talking about large amounts of stacking items, it wouldn't work;

using UnityEngine;
using System.Collections.Generic;
public class StackExchange : MonoBehaviour
{
    List<InventItem> rawInventory;
    List<InventSlot> groupedInventory;

    void Start () {
        rawInventory = new List<InventItem>();
        rawInventory.Add(new InventItem("apple" , true));
        rawInventory.Add(new InventItem("apple", true));
        rawInventory.Add(new InventItem("carrot", true));
        rawInventory.Add(new InventItem("knife", false));
        rawInventory.Add(new InventItem("knife", false));
        rawInventory.Add(new InventItem("knife", false));

        groupedInventory = new List<InventSlot>();
        foreach (InventItem i in rawInventory){
            proccessItem(i);
        }

        Debug.Log(getPrintableList(rawInventory));
        string s = "Grouped list:\n";
        foreach (InventSlot slot in groupedInventory){
            s += "{\n";
            for (int i = 0; i < slot.quantity; i++)
                s += slot.item.output();
            s += "}\n";
        }
        Debug.Log(s);
    }

    string getPrintableList (List<InventItem> list){
        string output = "{\n";
        foreach (var v in list){
            output += v.output() ;
        }
        output += "}\n";
        return output;
    }


    void proccessItem (InventItem item){
        foreach (var inventSlot in groupedInventory)
            if (inventSlot.item.name == item.name && inventSlot.item.isStackable){
                inventSlot.quantity++;
                return;
            }
        groupedInventory.Add ( new InventSlot (item));
    }

 }

class InventSlot{
    public InventItem item;
    public int quantity;
    public InventSlot (InventItem item){
        this.item = item;
        quantity = 1;
    }
}

class InventItem
{
    public string name;
    public bool isStackable;

    public InventItem (string name , bool isStackable){
        this.name = name;
        this.isStackable = isStackable;
    }

    public string output (){
        return "\tInventoryItem - name:" + name + ", stackable:" + isStackable + "\n";  
    }
}