Balanced

How balanced bundles work

The default bundling strategy applies the desired action to the targeted items selecting them in order to ensure a balanced and even distribution across groups (i.e. all groups contribute equally to the single promotional bundles that are recursively identified by the algorithm).

Bundles of type balanced can be created starting from at least two groups containing at least one item each. If the related actions.groups array is made by one group only, the Rule Engine will return an error. If one (or more) of the groups are empty, the action won't be applied.

To configure balanced bundles you just need to define the sorting logic within the sort object:

Key	Type	Required	Notes
type	String		If specified, must be "balanced".
sort	Object		Learn more here.

How the balanced algorithm works

1. The items within each targeted group are sorted according to the sort.direction function applied to the sort.attribute numeric field. The groups are also sorted considering the same logic on the same attribute (adding up its value for all the group's items).

2. The total quantity of units within each group is calculated by adding up the quantities of each item.

3. The minimum quantity of units across all group Q is the bottleneck of the algorithm (i.e. Q is the number of balanced bundles that will be created).

4. Starting from the top of the ordered list generated by the sorting, Q elements from each group are picked to be discounted, thus leading to Q discountable balanced bundles containing one item per group each.

If some items of the same group match the bundle's sort.direction function with the same numeric value of the field specified in the sort.attribute, they will be sorted as they are listed in the payload against which the rule is evaluated. If the computation for the total group sorting gives the same result the groups will be sorted in the same order as they are defined in the actions.groups array.

Example

Let's assume that a rule's conditions define the following groups of line items:

t-shirts

The group labeled as t-shirts contains 4 line items for a total of 10 units:

[
  {
    "id": "mnptRLjoXJ",
    "type": "line_items",
    "quantity": 1,
    "unit_amount_cents": 10000,
    "total_amount_cents": 10000,
    "sku": {
      "id": "zTdkkFXdgN",
      "code": "TSHIRT01"
    }
  },
  {
    "id": "jndtDLsoAM",
    "type": "line_items",
    "quantity": 2,
    "unit_amount_cents": 5000,
    "total_amount_cents": 10000,
    "sku": {
      "id": "xCKdTcQFQH",
      "code": "TSHIRT02"
    }
  },
  {
    "id": "AfetSAsqbY",
    "type": "line_items",
    "quantity": 3,
    "unit_amount_cents": 3000,
    "total_amount_cents": 9000,
    "sku": {
      "id": "meKHSeNbyN",
      "code": "TSHIRT03"
    }
  },
  {
    "id": "sjyTdAfrgY",
    "type": "line_items",
    "quantity": 4,
    "unit_amount_cents": 2000,
    "total_amount_cents": 8000,
    "sku": {
      "id": "uKtHCCJpWn",
      "code": "TSHIRT04"
    }
  }
]

polos

mugs

Let's consider a simple action that uses only the required parameters to be applied to a set of balanced bundles. The following action applies a 20% discount to all the possible bundles that can be created from the groups above, provided that they contain at least one item per group, prioritizing the items with the higher total amount:

"actions": [
  {
    "type": "percentage",
    "selector": "order.line_items.sku",
    "groups": [ "mugs", "polos", "t-shirts" ],
    "bundle": {
      "sort": {
        "attribute": "total_amount_cents",
        "direction": "desc"
      }
    },
    "value": 0.2
  }
]

1. Sorting

The items of the group are sorted based on their total amount, from the highest to the lowest. On top of that, the groups are sorted based on the sum of the total amount of each group's item, according to the same logic:

SKU	Group	Quantity	Item total amount	Group total amount
POLO02	polos	5	30000	37000
POLO01	polos	1	7000	37000
TSHIRT01	t-shirts	1	10000	37000
TSHIRT02	t-shirts	2	10000	37000
TSHIRT03	t-shirts	3	9000	37000
TSHIRT04	t-shirts	4	8000	37000
MUG02	mugs	1	4000	10000
MUG01	mugs	3	3000	10000
MUG03	mugs	1	3000	10000

TSHIRT01 ranks higher than TSHIRT02 within the t-shirts group even if they have the same total amount (10000) because this is how they are listed in the payload. The same happens to MUG01 and MUG03 within the mugs group. The elements of the polos groups rank higher than the elements of the t-shirts group even if the two groups have the same total amount (37000) because this is how they are listed in the actions.groups array.

2. Total quantity of units

The total quantity of units within each group is:

Group	Units
mugs	5
polos	6
t-shirts	10

3. Bottleneck

The group with the lowest total number of units limits the number of bundles that will be created. In this case the mugs group is the bottleneck, thus the discount will be applied to 5 bundles.

4. Bundles of items to be discounted

We can now pick 5 elements from each group, following the ordered list from top to bottom:

SKU	Group	Quantity	Discounted total amount
POLO02	polos	5	24000
TSHIRT01	t-shirts	1	8000
TSHIRT02	t-shirts	2	8000
TSHIRT03	t-shirts	2	4800
MUG02	mugs	1	3200
MUG01	mugs	3	2400
MUG03	mugs	1	2400

This is equivalent to picking one item per group while mugs units (our bottleneck) last, thus leading to the following 5 bundles to be discounted:

Bundle #1

SKU	Group	Quantity	Discounted unit amount
POLO02	polos	1	4800
TSHIRT01	t-shirts	1	8000
MUG02	mugs	1	3200

Bundle #2

SKU	Group	Quantity	Discounted unit amount
POLO02	polos	1	4800
TSHIRT02	t-shirts	1	4000
MUG01	mugs	1	800

Bundle #3

SKU	Group	Quantity	Discounted unit amount
POLO02	polos	1	4800
TSHIRT02	t-shirts	1	4000
MUG01	mugs	1	800

Bundle #4

SKU	Group	Quantity	Discounted unit amount
POLO02	polos	1	4800
TSHIRT03	t-shirts	1	2400
MUG01	mugs	1	800

Bundle #5

SKU	Group	Quantity	Discounted unit amount
POLO02	polos	1	4800
TSHIRT03	t-shirts	1	2400
MUG03	mugs	1	2400

Wrap-up

The results above confirm some general highlights of the balanced bundling strategy:

• An equal contribution of each group to the bundle formation is the distinctive feature. It's a quite strict requirement that leaves some items not discounted (in the analyzed case, 1 unit of POLO01, 1 unit of TSHIRT03, and 4 units of TSHIRT04), prioritizing the ones to discount based on the desired sorting logic.

• Only the elements of the group(s) with the minimum number of total units will be all discounted, and the total number of bundles identified will be equal to the number of total units of the group(s) that with minimum number of total units (in the analyzed case, the mugs group which has a total number of units equal to 5 and turns out to be the bottleneck of the algorithm).

• The total number of discounted units is given by the number of total units of the group with the minimum number of total units multiplied by the total number of groups (in the analyzed case, 5 * 3 = 15).