Python check for other rows while iterating through for loop

Question

So I have this list of tuples as shown below:

[(21, 2, 10.0),
(21, 104, 20.0),
(22, 1, 371.0),
(22, 104, 742.0),
(23, 1, 114.0),
(23, 104, 228.0),
(25, 1, 2.0),
(25, 104, 2.0)]

The context of each number, in order, is an id, sku_id and quantity. The goal is to go through each batch of tuples with the same ID and do the following:

• Check that any entry with a sku_id of 104 has another entry within the same quote_id
• That other entry must be half the quantity as the previous row.

In the example above, the rows with the id of 25 would match as the row with sku_id being 1 does not have half the quantity as the row with sku_id 104. This should be appended to a final set.

How can I accomplish this?

Answer 1

You could use collections.defaultdict to make a dictionary of the orders:

all_orders = defaultdict(dict)
for i, sku, qty in data:
    all_orders[i][sku] = qty

all_orders is now:

{
    21: {2: 10.0, 104: 20.0},
    22: {1: 371.0, 104: 742.0},
    23: {1: 114.0, 104: 228.0},
    25: {1: 2.0, 104: 2.0}
}

Then just loop through that and find if they meet the criteria

for i, orders in all_orders.items():
    if 104 not in orders:
        continue
    if len(orders) == 1:
        print("Needs to be more than one order if sku is 104")
        continue
    half_104_qty = orders[104] / 2
    for qty in orders.values():
        if qty < half_104_qty:
            continue
    else:
        print("There must be another order half the quantity of the order with sku 104")