Developer Guide and Reference

  • 2021.3
  • 06/28/2021
  • Public Content
Contents

Distributed Processing: Prediction of Ratings

The distributed processing mode assumes that the data set is split in
nblocks
blocks across computation nodes.

Algorithm Parameters

At the prediction stage, implicit ALS recommender in the distributed processing mode has the following parameters:
Parameter
Default Value
Description
computeStep
Not applicable
The parameter required to initialize the algorithm. Can be:
  • step1Local
    - the first step, performed on local nodes
algorithmFPType
float
The floating-point type that the algorithm uses for intermediate computations. Can be
float
or
double
.
method
defaultDense
Performance-oriented computation method, the only method supported by the algorithm.
nFactors
10
The total number of factors.
Use the one-step computation schema for implicit ALS recommender prediction in the distributed processing mode, as explained below and illustrated by the graphic for LaTex Math image.:

Step 1 - on Local Nodes

Prediction of rating uses partial models, which contain the parts of user factors LaTex Math image. and item factors LaTex Math image. produced at the training stage. Each pair of partial models LaTex Math image. is used to compute a numeric table with ratings LaTex Math image. that correspond to the user factors and item factors from the input partial models.
In this step, implicit ALS recommender-based prediction accepts the input described below. Pass the
Input ID
as a parameter to the methods that provide input for your algorithm. For more details, see Algorithms.
Input ID
Input
usersPartialModel
The partial model trained by the implicit ALS algorithm in the distributed processing mode. Stores user factors that correspond to the
i
-th data block.
itemsPartialModel
The partial model trained by the implicit ALS algorithm in the distributed processing mode. Stores item factors that correspond to the
j
-th data block.
In this step, implicit ALS recommender-based prediction calculates the result described below. Pass the
Result ID
as a parameter to the methods that access the results of your algorithm. For more details, see Algorithms.
Result ID
Result
prediction
Pointer to the LaTex Math image. numeric table with predicted ratings.
By default this table is an object of the
HomogenNumericTable
class, but you can define it as an object of any class derived from
NumericTable
except
PackedTriangularMatrix
,
PackedSymmetricMatrix
, and
CSRNumericTable
.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.