Training
Algorithm Parameters
Parameter
 Default Value
 Description
 

computeStep  Not applicable
 The parameter required to initialize the algorithm. Can be:
 
algorithmFPType  float  The floatingpoint type that the algorithm uses for intermediate computations. Can be
float or
double .
 
method  fastCSR  Performanceoriented computation method for CSR numeric tables, the only method supported by the algorithm.
 
nFactors  10
 The total number of factors.
 
maxIterations  5
 The number of iterations.
 
alpha  40
 The rate of confidence.
 
lambda  0.01
 The parameter of the regularization.
 
preferenceThreshold  0
 Threshold used to define preference values.
0 is the only threshold supported so far.

Computation Process
 Recompute all user factors using the input data sets and item factors computed previously.
 Recompute all item factors using input data sets in the transposed format and item factors computed previously.
Step 1  on Local Nodes
Input ID
 Input
 

partialModel  Partial model computed on the local node.

Result ID
 Result
 

outputOfStep1ForStep2  Pointer to the
f x
f numeric table with the sum of numeric tables calculated in Step 1.

Step 2  on Master Node
Input ID
 Input
 

inputOfStep2FromStep1  A collection of numeric tables computed on local nodes in
Step 1. The collection may contain objects of any class derived from
NumericTable except the
PackedTriangularMatrix class with the
lowerPackedTriangularMatrix layout.

Result ID
 Result
 

outputOfStep2ForStep4  Pointer to the
f x
f numeric table with merged crossproducts.

Step 3  on Local Nodes
Input ID
 Input


partialModel  Partial model computed on the local node.

offset  Numeric table of size 1x1 that holds the global index of the starting row of the input partial model. A part of the keyvalue data collection
offsets computed at the initialization stage of the algorithm.

Result ID
 Result
 

outputOfStep3ForStep4  A keyvalue data collection that contains partial models to be used in
Step 4. Each element of the collection contains an object of the
PartialModel class.

Step4  on Local Nodes
Input ID
 Input
 

partialModels  A keyvalue data collection with partial models that contain user factors/item factors computed in
Step 3. Each element of the collection contains an object of the
PartialModel class.
 
partialData  Pointer to the CSR numeric table that holds the
i th part of
the input data set , assuming that the data is divided by users/items.
 
inputOfStep4FromStep2 
Result ID
 Result
 

outputOfStep4ForStep1  Pointer to the partial implicit ALS model that corresponds to the
i th data block. The partial model stores user factors/item factors.
 
outputOfStep4ForStep3 