OnlineMultiLogisticRegression

class hana_ml.algorithms.pal.linear_model.OnlineMultiLogisticRegression(class_label, init_learning_rate=None, decay=None, drop_rate=None, step_boundaries=None, constant_values=None, enet_alpha=None, enet_lambda=None, shuffle=None, shuffle_seed=None, weight_avg=None, weight_avg_begin=None, learning_rate_type=None, general_learning_rate=None, stair_case=None, cycle=None, epsilon=None, window_size=None)

This algorithm is the online version of Multi-Class Logistic Regression, while the Multi-Class Logistic Regression is offline/batch version. The difference is that during training phase, for the offline/batch version algorithm it requires all training data to be fed into the algorithm in one batch, then it tries its best to output one model to best fit the training data. This infers that the computer must have enough memory to store all data, and can obtain all data in one batch. Online version algorithm applies in scenario that either or all these two assumptions are not right.

Parameters:
class_labela list of str

Indicates the class label and should be at least two class labels.

init_learning_ratefloat

The initial learning rate for learning rate schedule. Value should be larger than 0. Only valid when learning_rate_type is 'Inverse_time_decay', 'Exponential_decay', 'Polynomial_decay'.

decayfloat

Specify the learning rate decay speed for learning rate schedule. Larger value indicates faster decay. Value should be larger than 0. When learning_rate_type is 'exponential_decay', value should be larger than 1.

Only valid when learning_rate_type is 'Inverse_time_decay', 'Exponential_decay', 'Polynomial_decay'.

drop_rateint

Specify the decay frequency. There are apparent effect when stair_case is True. Value should be larger than 0.

Only valid when learning_rate_type is 'Inverse_time_decay', 'Exponential_decay', 'Polynomial_decay'.

step_boundarieslist of int, optional

Specify the step boundaries for regions where step size remains constant. The format of this parameter is a list of integers.

The step value start from 0(no need to be specified), and the values should be in ascending order(e. g. [5, 8, 15, 23]).

Empty value for this parameter is allowed.

Only valid when learning_rate_type is 'Piecewise_constant_decay'.

constant_valueslist of float, optional

Specifies the constant values for each region defined by step_boundaries. The format of this parameter is a list of float numbers.

There should always be one more value than step_boundaries since n boundary points should give out n+1 regions in total.

Only valid when learning_rate_type is 'Piecewise_constant_decay'.

enet_alphafloat, optional

Elastic-Net mixing parameter. The valid range is [0, 1]. When it is 0, this means Ridge penalty; When it is 1, it is Lasso penalty.

Only valid when enet_lambda is not 0.0.

Defaults to 1.0.

enet_lambdafloat, optional

Penalized constant. The value should be larger than or equal to 0.0. The higher the value, the stronger the regularization. When it equal to 0.0, there is no regularization.

Defaults to 0.0.

shufflebool, optonal

Boolean value indicating whether need to shuffle the row order of observation data. False means keeping original order; True means performing shuffle operation.

Defaults to False.

shuffle_seedint, optonal

The seed is used to initialize the random generator to perform shuffle operation. The value of this parameter should be larger than or equal to 0. If need to reproduce the result when performing shuffle operation, please set this value to non-zero. Only valid when shuffle is True.

Defaults to 0.

weight_avgbool, optonal

Boolean value indicating whether need to perform average operator over output model. False means directly output model; True means perform average operator over output model. Currently only support Polyak Ruppert Average.

Defaults to False.

weight_avg_beginint, optonal

Specify the beginning step counter to perform the average operator over model. The value should be larger than or equal to 0. When current step counter is less than this parameter, just directly output model.Only valid when weight_avg is True.

Defaults to 0.

learning_rate_typestr, optonal

Specify the learning rate type for SGD algorithm.

  • 'Inverse_time_decay'

  • 'Exponential_decay'

  • 'Polynomial_decay'

  • 'Piecewise_constant_decay'

  • 'AdaGrad'

  • 'AdaDelta'

  • 'RMSProp'

Defaults to 'RMSProp'.

general_learning_ratefloat, optonal

Specify the general learning rate used in AdaGrad and RMSProp. The value should be larger than 0. Only valid when learning_rate_type is 'AdaGrad', 'RMSProp'.

Defaults to 0.001.

stair_casebool, optonal

Boolean value indicate the drop way of step size. False means drop step size smoothly. Only valid when learning_rate_type is 'Inverse_time_decay', 'Exponential_decay'.

Defaults to False.

cyclebool, optonal

indicate whether need to cycle from the start when reaching specified end learning rate. False means do not cycle from the start; True means cycle from the start.

Only valid when learning_rate_type is 'Polynomial_decay'.

Defaults to False.

epsilonfloat, optonal

This parameter has multiple purposes depending on the learn rate type. The value should be within (0, 1). When used in learn rate type 0 and 1, it represent the smallest allowable step size. When step size reach this value, it will no longer change. When used in learning_rate_type 'Polynomial_decay', it represent the end learn rate. When used in learning_rate_type 'AdaGrad', 'AdaDelta', 'RMSProp', it is used to avoid dividing by 0.

Only valid when learning_rate_type is not 'Piecewise_constant_decay'.

Defaults to 1E-8.

window_sizefloat, optonal

This parameter controls the moving window size of recent steps. The value should be in range (0, 1). Larger value means more steps are kept in track. Only valid when learning_rate_type is 'AdaDelta', 'RMSProp'.

Defaults to 0.9.

Examples

>>> omlr = OnlineMultiLogisticRegression(class_label=['0','1','2'], enet_lambda=0.01,
                                         enet_alpha=0.2, weight_avg=True,
                                         weight_avg_begin=8, learning_rate_type='rmsprop',
                                         general_learning_rate=0.1,
                                         window_size=0.9, epsilon=1e-6)

In each run, you could invoke partial_fit() to train the model with a new DataFrame. The use of df_1 as an example, is shown below.

>>> omlr.partial_fit(data=df_1, label='Y', features=['X1', 'X2'])

Output:

>>> omlr.coef_.collect()
>>> omlr.online_result_.collect()

Perform predict():

>>> onlinelr.predict(data=df_predict).collect()

Perform score():

>>> onlinelr.predict(data=df_score).collect()
Attributes:
coef_DataFrame

Values of the coefficients.

online_result_DataFrame

Online Model content.

Methods

partial_fit(data[, key, features, label, ...])

Online training based on each round of data.

predict(data[, key, features])

Predict dependent variable values based on a fitted model.

score(data[, key, features, label])

Returns the coefficient of determination R2 of the prediction.
partial_fit(data, key=None, features=None, label=None, thread_ratio=None, progress_indicator_id=None)

Online training based on each round of data.

Parameters:
dataDataFrame

Training data.

keystr, optional

Name of the ID column. If key is not provided, then:

  • if data is indexed by a single column, then key defaults to that index column;

  • otherwise, it is assumed that data contains no ID column.

featuresa list of str, optional

Names of the feature columns. If features is not provided, it defaults to all non-ID, non-label columns.

labelstr, optional

Name of the dependent variable.

If label is not provided, it defaults to the last column.

thread_ratiofloat, optional

Adjusts the percentage of available threads to use, from 0 to 1. A value of 0 indicates the use of a single thread, while 1 implies the use of all possible current threads. Values outside the range will be ignored and this function heuristically determines the number of threads to use.

Defaults to 0.0.

progress_indicator_idstr, optional

The ID of progress indicator for model evaluation/parameter selection.

Progress indicator deactivated if no value provided.

Returns:
A fitted object of class "OnlineMultiLogisticRegression".
predict(data, key=None, features=None)

Predict dependent variable values based on a fitted model.

Parameters:
dataDataFrame

Independent variable values to predict for.

keystr, optional

Name of the ID column.

Mandatory if data is not indexed, or the index of data contains multiple columns.

Defaults to the single index column of data if not provided.

featuresa list of str, optional

Names of the feature columns.

If features is not provided, it defaults to all non-ID columns.

Returns:
DataFrame

Predicted values, structured as follows:

  • ID column: with same name and type as data 's ID column.

  • VALUE: type DOUBLE, representing predicted values.

score(data, key=None, features=None, label=None)

Returns the coefficient of determination R2 of the prediction.

Parameters:
dataDataFrame

Data on which to assess model performance.

keystr, optional

Name of the ID column.

Mandatory if data is not indexed, or the index of data contains multiple columns.

Defaults to the single index column of data if not provided.

featuresa list of str, optional

Names of the feature columns.

If features is not provided, it defaults all non-ID, non-label columns.

labelstr, optional

Name of the dependent variable.

If label is not provided, it defaults to the last column.

Returns:
float

Returns the coefficient of determination R2 of the prediction.

Inherited Methods from PALBase

Besides those methods mentioned above, the OnlineMultiLogisticRegression class also inherits methods from PALBase class, please refer to PAL Base for more details.