Collect session events
Aggregate click or view events into ordered sessions with timestamps and minimal session identifiers; filter bot traffic and very short sessions.
Predict next item in sessions. Respect sequential context.
Session-based recommendation predicts the next item(s) a user will interact with inside a single browsing or transaction session. It relies on short-term sequential patterns, recency, and context rather than long-term user profiles. Important concerns include session length variability, cold-start sessions, and evaluation with next-item ranking metrics such as Recall@K and MRR.
Learning concept · Not a validated service
Session-based recommendation predicts the next item(s) a user will interact with inside a single browsing or transaction session. It relies on short-term sequential patterns, recency, and context rather than long-term user profiles. Important concerns include session length variability, cold-start sessions, and evaluation with next-item ranking metrics such as Recall@K and MRR.
A proposed application: a product-detail page that suggests the next product a browsing user is likely to view or add to cart, using only the current session events. This extension is not implemented by the supplied starter code.
Aggregate click or view events into ordered sessions with timestamps and minimal session identifiers; filter bot traffic and very short sessions.
Start with simple sequential baselines (item-to-item co-occurrence or last-item popularity within sessions) before training sequence models.
Use next-item ranking metrics (Recall@K, MRR) on chronologically split test sessions and inspect failure cases by session length.
Provide fallbacks for very short sessions, monitor recommendation hit-rate and latency, and log served recommendations for offline analysis.
The supplied starter builds a small synthetic user-item ratings table, pivots it to a user-by-item rating matrix, computes cosine similarity between users, selects the most similar user to a target, and recommends that neighbour's unrated items. It is a simple user-based collaborative filtering example and does not implement session- or sequence-based methods.
matrix = ratings.pivot_table(index="user", columns="item", values="rating").fillna(0)
user_similarity = pd.DataFrame(
cosine_similarity(matrix),
index=matrix.index,
columns=matrix.index,
)
target_user = "user_1"
neighbor = user_similarity[target_user].drop(target_user).idxmax()
unseen_items = matrix.loc[target_user][matrix.loc[target_user] == 0].index
scores = matrix.loc[neighbor, unseen_items].sort_values(ascending=False)The code is user-based collaborative filtering on a small hand-crafted rating table and uses no session logs, no ordered event sequences, and no next-item or sequence model required by session-based recommendations.
Proposed extension: replace the synthetic user-rating table with ordered session event logs and train a next-item model (item-to-item Markov, GRU4Rec or transformer) to predict the next click within a session.
This is a potential application pathway, not a delivered product. The supplied starter does not implement this service or validate it with real users.
Networkers Home runs this topic inside its AI Engineer Course, with placement support and hands-on labs.