lenskit.splitting.LastN

class lenskit.splitting.LastN(n, field='timestamp')

Bases: HoldoutMethod

Select a fixed number of test rows per user/item, based on ordering by a field.

Stability:

Caller (see Stability Levels).

Parameters:

• n (int) – The number of test items to select.

• field (str) – The field to order by.

n: int

field: str

__call__(items)

Subset an item list (in the uncommon case of item-based holdouts, the item list actually holds user IDs).

Parameters:

• udf – The item list from which holdout items should be selected.

• items (lenskit.data.ItemList)

Returns:

The list of test items.

Return type:

lenskit.data.ItemList