4.2.11 Non-Negative Matrix Factorization

The ore.odmNMF function builds an in-database Non-Negative Matrix Factorization (NMF) model for feature extraction.

Each feature extracted by NMF is a linear combination of the original attribution set. Each feature has a set of non-negative coefficients, which are a measure of the weight of each attribute on the feature. If the argument allow.negative.scores is TRUE, then negative coefficients are allowed.

For information on the ore.odmNMF function arguments, call help(ore.odmNMF).

Settings for a Non-Negative Matrix Factorization Models

The following table lists settings that apply to Non-Negative Matrix Factorization models.

Table 4-11 Non-Negative Matrix Factorization Model Settings

Setting Name	Setting Value	Description
NMFS_CONV_TOLERANCE	TO_CHAR(0< numeric_expr <=0.5)	Convergence tolerance for NMF algorithm Default is 0.05
NMFS_NONNEGATIVE_SCORING	NMFS_NONNEG_SCORING_ENABLE NMFS_NONNEG_SCORING_DISABLE	Whether negative numbers should be allowed in scoring results. When set to NMFS_NONNEG_SCORING_ENABLE, negative feature values will be replaced with zeros. When set to NMFS_NONNEG_SCORING_DISABLE, negative feature values will be allowed. Default is NMFS_NONNEG_SCORING_ENABLE
NMFS_NUM_ITERATIONS	TO_CHAR(1 <= numeric_expr <=500)	Number of iterations for NMF algorithm Default is 50
NMFS_RANDOM_SEED	TO_CHAR(numeric_expr)	Random seed for NMF algorithm. Default is –1.

Example 4-21 Using the ore.odmNMF Function

This example creates an NMF model on a training data set and scores on a test data set.

training.set <- ore.push(npk[1:18, c("N","P","K")])
scoring.set <- ore.push(npk[19:24, c("N","P","K")])
nmf.mod <- ore.odmNMF(~., training.set, num.features = 3)
features(nmf.mod)
summary(nmf.mod)
predict(nmf.mod, scoring.set)

Listing for This Example

R> training.set <- ore.push(npk[1:18, c("N","P","K")])
R> scoring.set <- ore.push(npk[19:24, c("N","P","K")])
R> nmf.mod <- ore.odmNMF(~., training.set, num.features = 3)
R> features(nmf.mod)
   FEATURE_ID ATTRIBUTE_NAME ATTRIBUTE_VALUE  COEFFICIENT
1           1              K               0 3.723468e-01
2           1              K               1 1.761670e-01
3           1              N               0 7.469067e-01
4           1              N               1 1.085058e-02
5           1              P               0 5.730082e-01
6           1              P               1 2.797865e-02
7           2              K               0 4.107375e-01
8           2              K               1 2.193757e-01
9           2              N               0 8.065393e-03
10          2              N               1 8.569538e-01
11          2              P               0 4.005661e-01
12          2              P               1 4.124996e-02
13          3              K               0 1.918852e-01
14          3              K               1 3.311137e-01
15          3              N               0 1.547561e-01
16          3              N               1 1.283887e-01
17          3              P               0 9.791965e-06
18          3              P               1 9.113922e-01
R> summary(nmf.mod)
 
Call:
ore.odmNMF(formula = ~., data = training.set, num.features = 3)
 
Settings: 
                                              value
feat.num.features                                 3
nmfs.conv.tolerance                             .05
nmfs.nonnegative.scoring nmfs.nonneg.scoring.enable
nmfs.num.iterations                              50
nmfs.random.seed                                 -1
prep.auto                                        on
 
Features: 
   FEATURE_ID ATTRIBUTE_NAME ATTRIBUTE_VALUE  COEFFICIENT
1           1              K               0 3.723468e-01
2           1              K               1 1.761670e-01
3           1              N               0 7.469067e-01
4           1              N               1 1.085058e-02
5           1              P               0 5.730082e-01
6           1              P               1 2.797865e-02
7           2              K               0 4.107375e-01
8           2              K               1 2.193757e-01
9           2              N               0 8.065393e-03
10          2              N               1 8.569538e-01
11          2              P               0 4.005661e-01
12          2              P               1 4.124996e-02
13          3              K               0 1.918852e-01
14          3              K               1 3.311137e-01
15          3              N               0 1.547561e-01
16          3              N               1 1.283887e-01
17          3              P               0 9.791965e-06
18          3              P               1 9.113922e-01
R> predict(nmf.mod, scoring.set)
         '1'       '2'        '3' FEATURE_ID
19 0.1972489 1.2400782 0.03280919          2
20 0.7298919 0.0000000 1.29438165          3
21 0.1972489 1.2400782 0.03280919          2
22 0.0000000 1.0231268 0.98567623          2
23 0.7298919 0.0000000 1.29438165          3
24 1.5703239 0.1523159 0.00000000          1