Developer Guide and Reference

  • 2021.2
  • 03/26/2021
  • Public Content
Contents

Distributed Processing

This mode assumes that the data set is split into
nblocks
blocks across computation nodes.

Parameters

Centroid initialization for K-Means clustering in the distributed processing mode has the following parameters:
Parameter
Method
Default Valude
Description
computeStep
any
Not applicable
The parameter required to initialize the algorithm. Can be:
  • step1Local
    - the first step, performed on local nodes. Applicable for all methods.
  • step2Master
    - the second step, performed on a master node. Applicable for deterministic and random methods only.
  • step2Local
    - the second step, performed on local nodes. Applicable for
    plusPlus
    and
    parallelPlus
    methods only.
  • step3Master
    - the third step, performed on a master node. Applicable for
    plusPlus
    and
    ParallelPlus
    methods only.
  • step4Local
    - the forth step, performed on local nodes. Applicable for
    plusPlus
    and
    parallelPlus
    methods only.
  • step5Master
    - the fifth step, performed on a master node. Applicable for
    plusPlus
    and
    parallelPlus
    methods only.
algorithmFPType
any
float
The floating-point type that the algorithm uses for intermediate computations. Can be
float
or
double
.
method
Not applicable
defaultDense
Available initialization methods for K-Means clustering:
  • defaultDense
    - uses first nClusters feature vectors as initial centroids
  • deterministicCSR
    - uses first nClusters feature vectors as initial centroids for data in a CSR numeric table
  • randomDense
    - uses random nClusters feature vectors as initial centroids
  • randomCSR
    - uses random nClusters feature vectors as initial centroids for data in a CSR numeric table
  • plusPlusDense
    - uses K-Means++ algorithm [Arthur2007]
  • plusPlusCSR
    - uses K-Means++ algorithm for data in a CSR numeric table
  • parallelPlusDense
    - uses parallel K-Means++ algorithm [Bahmani2012]
  • parallelPlusCSR
    - uses parallel K-Means++ algorithm for data in a CSR numeric table
For more details, see the algorithm description.
nClusters
any
Not applicable
The number of centroids. Required.
nRowsTotal
any
0
The total number of rows in all input data sets on all nodes. Required in the distributed processing mode in the first step.
offset
any
Not applicable
Offset in the total data set specifying the start of a block stored on a given local node. Required.
oversamplingFactor
  • parallelPlusDense
  • parallelPlusCSR
0.5
A fraction of
nClusters
in each of
nRounds
of parallel K-Means++. LaTex Math image. points are sampled in a round. For details, see [Bahmani2012], section 3.3.
nRounds
  • parallelPlusDense
  • parallelPlusCSR
5
The number of rounds for parallel K-Means++. LaTex Math image. must be greater than
nClusters
. For details, see [Bahmani2012], section 3.3.
firstIteration
  • parallelPlusDense
  • parallelPlusCSR
  • plusPlusDense
  • plusPlusCSR
false
Set to true if
step2Local
is called for the first time.
outputForStep5Required
  • parallelPlusDense
  • parallelPlusCSR
false
Set to true if
step4Local
is called on the last iteration of the Step 2 - Step 4 loop.
Centroid initialization for K-Means clustering follows the general schema described in Algorithms.
plusPlus
methods
parrallelPlus
methods

Step 1 - on Local Nodes (
deterministic
,
random
,
plusPlus
, and
parallelPlus
methods)

plusPlus
methods
parrallelPlus
methods
In this step, centroid initialization for K-Means clustering 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
data
Pointer to the LaTex Math image. numeric table that represents the
i
-th data block on the local node.
While the input for
defaultDense
,
randomDense
,
plusPlusDense
, and
parallelPlusDense
methods can be an object of any class derived from
NumericTable
, the input for
deterministicCSR
,
randomCSR
,
plusPlusCSR
, and
parallelPlusCSR
methods can only be an object of the
CSRNumericTable
class.
In this step, centroid initialization for K-Means clustering calculates the results 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
partialCentroids
Pointer to the LaTex Math image. numeric table with the centroids computed on the local node.
By default, this result is an object of the
HomogenNumericTable
class, but you can define the result as an object of any class derived from
NumericTable
except
PackedTriangularMatrix
,
PackedSymmetricMatrix
, and
CSRNumericTable
.

Step 2 - on Master Node (
deterministic
and
random
methods)

This step is applicable for
deterministic
and
random
methods only. Centroid initialization for K-Means clustering accepts the input from each local node 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
partialResuts
A collection that contains results computed in Step 1 on local nodes (two numeric tables from each local node).
In this step, centroid initialization for K-Means clustering calculates the results 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
centroids
Pointer to the LaTex Math image. numeric table with centroids.
By default, this result is an object of the
HomogenNumericTable
class, but you can define the result as an object of any class derived from
NumericTable
except
PackedTriangularMatrix
,
PackedSymmetricMatrix
, and
CSRNumericTable
.

Step 2 - on Local Nodes (
plusPlus
and
parallelPlus
methods)

plusPlus
methods
parrallelPlus
methods
This step is applicable for
plusPlus
and
parallelPlus
methods only. Centroid initialization for K-Means clustering accepts the input from each local node 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
data
Pointer to the LaTex Math image. numeric table that represents the
i
-th data block on the local node.
While the input for
defaultDense
,
randomDense
,
plusPlusDense
, and
parallelPlusDense
methods can be an object of any class derived from
NumericTable
, the input for
deterministicCSR
,
randomCSR
,
plusPlusCSR
, and
parallelPlusCSR
methods can only be an object of the
CSRNumericTable
class.
inputOfStep2
Pointer to the LaTex Math image. numeric table with the centroids calculated in the previous steps (Step 1 or Step 4).
The value of
m
is defined by the method and iteration of the algorithm:
  • plusPlus
    method:
    m = 1
  • parallelPlus
    method:
    • m = 1
      for the first iteration of the Step 2 - Step 4 loop
    • LaTex Math image. for other iterations
This input can be an object of any class derived from
NumericTable
, except
CSRNumericTable
,
PackedTriangularMatrix
, and
PackedSymmetricMatrix
.
internalInput
Pointer to the
DataCollection
object with the internal data of the distributed algorithm used by its local nodes in Step 2 and Step 4. The
DataCollection
is created in Step 2 when
firstIteration
is set to
true
, and then the
DataCollection
should be set from the partial result as an input for next local steps (Step 2 and Step 4).
In this step, centroid initialization for K-Means clustering calculates the results 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
outputOfStep2ForStep3
Pointer to the LaTex Math image. numeric table that contains the overall error accumulated on the node. For a description of the overall error, see K-Means Clustering Details.
outputOfStep2ForStep5
Applicable for
parallelPlus
methods only and calculated when
outputForStep5Required
is set to
true
. Pointer to the LaTex Math image. numeric table with the ratings of centroid candidates computed on the previous steps and LaTex Math image.. For a description of ratings, see K-Means Clustering Details.
By default, these results are objects of the
HomogenNumericTable
class, but you can define the result as an object of any class derived from
NumericTable
except
PackedTriangularMatrix
,
PackedSymmetricMatrix
, and
CSRNumericTable
.

Step 3 - on Master Node (
plusPlus
and
parallelPlus
methods)

plusPlus
methods
parrallelPlus
methods
This step is applicable for plusPlus and parallelPlus methods only. Centroid initialization for K-Means clustering accepts the input from each local node 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
inputOfStep3FromStep2
A key-value data collection that maps parts of the accumulated error to the local nodes:
i
-th element of this collection is a numeric table that contains overall error accumulated on the
i
-th node.
In this step, centroid initialization for K-Means clustering calculates the results 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
outputOfStep3ForStep4
A key-value data collection that maps the input from Step 4 to local nodes:
i
-th element of this collection is a numeric table that contains the input from Step 4 on the i-th node.
Note that Step 3 may produce no input for Step 4 on some local nodes, which means the collection may not contain the
i
-th node entry. The single element of this numeric table LaTex Math image., where the overall error LaTex Math image. calculated on the node. For a description of the overall error, see K-Means Clustering Details.
This value defines the probability to sample a new centroid on the
i
-th node.
outputOfStep3ForStep5
Applicable for parallelPlus methods only. Pointer to the service data to be used in Step 5.

Step 4 - on Local Nodes (
plusPlus
and
parallelPlus
methods)

plusPlus
methods
parrallelPlus
methods
This step is applicable for plusPlus and parallelPlus methods only. Centroid initialization for K-Means clustering accepts the input from each local node 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
data
Pointer to the LaTex Math image. numeric table that represents the
i
-th data block on the local node.
While the input for
defaultDense
,
randomDense
,
plusPlusDense
, and
parallelPlusDense
methods can be an object of any class derived from
NumericTable
, the input for
deterministicCSR
,
randomCSR
,
plusPlusCSR
, and
parallelPlusCSR
methods can only be an object of the
CSRNumericTable
class.
inputOfStep4FromStep3
Pointer to the LaTex Math image. numeric table with the values calculated in Step 3.
The value of
m
is defined by the method of the algorithm:
  • plusPlus
    method:
    m = 1
  • parallelPlus
    method: LaTex Math image., LaTex Math image.
This input can be an object of any class derived from
NumericTable
, except
CSRNumericTable
,
PackedTriangularMatrix
, and
PackedSymmetricMatrix
.
internalInput
Pointer to the
DataCollection
object with the internal data of the distributed algorithm used by its local nodes in Step 2 and Step 4. The
DataCollection
is created in Step 2 when
firstIteration
is set to
true
, and then the
DataCollection
should be set from the partial result as the input for next local steps (Step 2 and Step 4).
In this step, centroid initialization for K-Means clustering calculates the results 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
outputOfStep4
Pointer to the LaTex Math image. numeric table that contains centroids computed on this local node, where
m
equals to the one in
inputOfStep4FromStep3
.
By default, this result is an object of the
HomogenNumericTable
class, but you can define the result as an object of any class derived from
NumericTable
except
CSRNumericTable
,
PackedTriangularMatrix
, and
PackedSymmetricMatrix
.

Step 5 - on Master Node (
parallelPlus
methods)

This step is applicable for parallelPlus methods only. Centroid initialization for K-Means clustering accepts the input from each local node 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
inputCentroids
A data collection with the centroids calculated in Step 1 or Step 4. Each item in the collection is the pointer to LaTex Math image. numeric table, where the value of
m
is defined by the method and the iteration of the algorithm:
parallelPlus
method:
  • m = 1
    for the data added as the output of Step 1
  • LaTex Math image., LaTex Math image. for the data added as the output of Step 4
Each numeric table can be an object of any class derived from
NumericTable
, except
CSRNumericTable
,
PackedTriangularMatrix
, and
PackedSymmetricMatrix
.
inputOfStep5FromStep2
A data collection with the items calculated in Step 2 on local nodes. For a detailed definition, see
outputOfStep2ForStep5
above.
inputOfStep5FromStep3
Pointer to the service data generated as the output of Step 3 on master node. For a detailed definition, see
outputOfStep3ForStep5
above.
In this step, centroid initialization for K-Means clustering calculates the results 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
centroids
Pointer to the LaTex Math image. numeric table with centroids.
By default, this result is an object of the
HomogenNumericTable
class, but you can define the result as an object of any class derived from
NumericTable
except
PackedTriangularMatrix
,
PackedSymmetricMatrix
, and
CSRNumericTable
.

Product and Performance Information

1

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