Error `AttributeError: 'implicit.evaluation._memoryviewslice' object has no attribute 'dtype'` when calling `mean_average_precision_at_k` function

[MRossa157]

Hello! I encountered an issue when using the mean_average_precision_at_k function from the implicit library.

Problem Description:

When calling the mean_average_precision_at_k function, the following error occurs:

AttributeError: 'implicit.evaluation._memoryviewslice' object has no attribute 'dtype'

Context:

• Operating System: Windows 10
• Python: 3.10.7
• implicit library version: 0.7.2
• Installed dependencies:

  [tool.poetry.dependencies]
  python = "^3.10.7"
  pandas = "^2.2.2"
  implicit = "^0.7.2"

Steps to Reproduce:

1. Installed the implicit library version 0.7.2.
2. Called the mean_average_precision_at_k function with the following parameters:

   metric_map = mean_average_precision_at_k(
       model,
       csr_train,
       csr_test,
       K=6,
       show_progress=True,
   )

3. Encountered the above-mentioned error.

Expected Behavior:

The function should return the MAP@K metric value without errors.

Additional Information:

• Tried reinstalling the library and its dependencies, but the error persists.
• The code includes the following imports:

  import numpy as np
  import pandas as pd
  from implicit.cpu.als import AlternatingLeastSquares as ALScpu
  from implicit.evaluation import mean_average_precision_at_k
  from scipy.sparse import coo_matrix

I would appreciate any assistance in resolving this issue.

[fkurushin]

Hi @MRossa157 ! I have trained model with python implicit package and faced the same problem:

The minimum example to reproduce the error

import os
import random
import pandas as pd
from scipy.sparse import csr_matrix
from implicit.evaluation import train_test_split, ndcg_at_k, mean_average_precision_at_k
from implicit.gpu.als import AlternatingLeastSquares

os.environ['OPENBLAS_NUM_THREADS']="1"
os.environ['CUDA_VISIBLE_DEVICES']="0"

# init random data
n_actions = 100000
max_uid = 100000
max_action_id = 10000

df = pd.DataFrame(data={
    "user_id" : [random.randint(1, max_uid) for i in range(0, n_actions)],
    "action" : [random.randint(1, max_action_id) for i in range(0, n_actions)],
    "impression" : [1 for i in range(0, n_actions)]
})

# convert to sparse format
user_rows = [uid for uid in df.user_id.tolist()]
query_cols = [st for st in df.action.tolist()]
qvecs = csr_matrix((df.impression, (user_rows, query_cols)))

# train test split and model training
train_user_items, test_user_items = train_test_split(qvecs, train_percentage=0.9, random_state=19)

model = AlternatingLeastSquares(factors=130, regularization=0.05, alpha=1.0, calculate_training_loss=True)
model.fit(train_user_items)

# calculate ndcg
ndcg = ndcg_at_k(model, train_user_items, test_user_items, K=14, show_progress=True, num_threads=1)

packages version:
implicit-0.7.2 (built from source)
python-3.11.2
cuda-12.3

os:
Debian GNU/Linux 12

[sorlandet]

Updating to scipy 1.14.1 should resolve the issue.

[gdragotto]

Updating to scipy 1.14.1 should resolve the issue.

It does not in the wheels, at least on my side. Did you compile from scratch?

[gdragotto]

Update: Python workaround to perform the evaluation "manually"

def ranking_metrics_at_k(model, train_user_items, test_user_items, K=10, show_progress=True):
    """
    Calculates ranking metrics (Precision@K, MAP@K, NDCG@K, AUC) for a trained model.

    Parameters:
        model : Trained ALS model (or other Implicit model).
        train_user_items : csr_matrix
            User-item interaction matrix used for training.
        test_user_items : csr_matrix
            User-item interaction matrix for evaluation.
        K : int
            Number of items to evaluate.
        show_progress : bool
            Show a progress bar during evaluation.

    Returns:
        dict : Dictionary with precision, MAP, NDCG, and AUC scores.
    """

    # Ensure matrices are in CSR format
    train_user_items = train_user_items.tocsr()
    test_user_items = test_user_items.tocsr()

    num_users, num_items = test_user_items.shape
    relevant = 0
    total_precision_div = 0
    total_map = 0
    total_ndcg = 0
    total_auc = 0
    total_users = 0

    # Compute cumulative gain for NDCG normalization
    cg = 1.0 / np.log2(np.arange(2, K + 2))  # Discount factor
    cg_sum = np.cumsum(cg)  # Ideal DCG normalization

    # Get users with at least one item in the test set
    users_with_test_data = np.where(np.diff(test_user_items.indptr) > 0)[0]

    # Progress bar
    progress = tqdm.tqdm(total=len(users_with_test_data), disable=not show_progress)

    batch_size = 1000
    start_idx = 0

    while start_idx < len(users_with_test_data):
        batch_users = users_with_test_data[start_idx:start_idx + batch_size]
        recommended_items, _ = model.recommend(batch_users, train_user_items[batch_users], N=K)
        start_idx += batch_size

        for user_idx, user_id in enumerate(batch_users):
            test_items = set(test_user_items.indices[test_user_items.indptr[user_id]:test_user_items.indptr[user_id + 1]])
            
            if not test_items:
                continue  # Skip users without test data

            num_relevant = len(test_items)
            total_precision_div += min(K, num_relevant)

            ap = 0
            hit_count = 0
            auc = 0
            idcg = cg_sum[min(K, num_relevant) - 1]  # Ideal Discounted Cumulative Gain (IDCG)
            num_negative = num_items - num_relevant

            for rank, item in enumerate(recommended_items[user_idx]):
                if item in test_items:
                    relevant += 1
                    hit_count += 1
                    ap += hit_count / (rank + 1)
                    total_ndcg += cg[rank] / idcg
                else:
                    auc += hit_count  # Accumulate hits for AUC calculation

            auc += ((hit_count + num_relevant) / 2.0) * (num_negative - (K - hit_count))
            total_map += ap / min(K, num_relevant)
            total_auc += auc / (num_relevant * num_negative)
            total_users += 1
        
        progress.update(len(batch_users))

    progress.close()

    # Compute final metrics
    precision = relevant / total_precision_div if total_precision_div > 0 else 0
    mean_ap = total_map / total_users if total_users > 0 else 0
    mean_ndcg = total_ndcg / total_users if total_users > 0 else 0
    mean_auc = total_auc / total_users if total_users > 0 else 0

    return {
        "precision": precision,
        "map": mean_ap,
        "ndcg": mean_ndcg,
        "auc": mean_auc
    }

[InputMismatchError]

Installing the whole 'implicit' module using conda-forge instead of pip solved the issue for me. I wasn't able to run any evaluation functions getting the same error, now I can run any of them.

Just use "conda install -c conda-forge implicit"

[sillykelvin]

Updating to scipy 1.14.1 should resolve the issue.

I installed implicit by uv add implicit, by default it installed implicit 0.7.2 and scipy with a higher version 1.15.2. Then I downgraded scipy to 1.14.1 with uv add 'scipy==1.14.1' and it worked.