# Reference¶

## Seldonian Algorithm¶

class seldonian.algorithm.SeldonianAlgorithm

Bases: abc.ABC

Abstract class which represents the basic functions of a Seldonian Algorithm. This class can be considered as a starting point for implementing your own Seldonian algorithm.

Read more about the Seldonian Approach in Preventing undesirable behavior of intelligent machines

abstract _safetyTest(**kwargs)

Run the safety test on the trained model from the candidate selection part i.e. the fit() function. It is also used to predict the $$g(\theta)$$ value used in candidate selection.

:param kwargs Key value arguments sent to the subclass implementation of safety test. :return Depending on the implementation, it will either return 0 if it passes or 1 if it doesn’t. Or, it will also return the $$g(\theta)$$ value if it does not pass the safety test. Use the safetyTest() method to get a boolean value.

abstract data()

Access the training data used by the model.

Returns

Tuple (Training data, labels)

abstract fit(**kwargs)

Abstract method that is used to train the model. Also, this is the candidate selection part of the Seldonian Algorithm.

Parameters

kwargs – key value arguments sent to the fit function

Returns

abstract predict(X)

Predict the output of the model on the the input X.

Parameters

X – input data to be predicted by the model.

Returns

output predictions for each sample in the input X

safetyTest(**kwargs)

A wrapper for the _safetyTest method that return a Boolean indicating whether the model passed the safety test.

Parameters

kwargs – Key-value arguments that is passed directly to _safetyTest.

Returns

• True if model passed the safety test.

• False if the model fails the safety test.

## Seldonian Abstract classes¶

Use this as a base class to implement your own fair model using the Seldonian approach.

class seldonian.seldonian.LogisticRegressionSeldonianModel(X, y, g_hats=[], safety_data=None, test_size=0.5, verbose=True, hard_barrier=False, stratify=False, random_seed=0)

Implements a Logistic Regression classifier using scipy.optimize package as the optimizer using the Seldonian Approach for training the model. Have a look at the scipy.optimize.minimize reference for more information. You can use any of the methods listen in the method input of this SciPy function as a parameter to the fit() method call.

__init__(X, y, g_hats=[], safety_data=None, test_size=0.5, verbose=True, hard_barrier=False, stratify=False, random_seed=0)

Initialize self. See help(type(self)) for accurate signature.

_safetyTest(theta=None, predict=False, ub=True)

This is the mehtod that implements the safety test. for this model.

Parameters
• theta – Model parameters to be used to run the safety test. Default - None. If None, the current model parameters used.

• predictDefault - False. Indicate whether you want to predict the upper bound of $$g(\theta)$$ using the candidate set (this is used when running candidate selection).

• ub – returns the upper bound if True. Else, it returns the calculated value. Default- True.

Returns

Returns the value $$max\{0, g(\theta) | X\}$$ if predict = False , else $$max\{0, \hat{g}(\theta) | X\}$$.

data()

Access the training data used by the model.

Returns

Tuple (Training data, labels)

fit(opt='Powell')

Abstract method that is used to train the model. Also, this is the candidate selection part of the Seldonian Algorithm.

Parameters

kwargs – key value arguments sent to the fit function

Returns

predict(X)

Predict the output of the model on the the input X.

Parameters

X – input data to be predicted by the model.

Returns

output predictions for each sample in the input X

class seldonian.seldonian.PDISSeldonianPolicyCMAES(data, states, actions, gamma, threshold=2, test_size=0.4, multiprocessing=True)
__init__(data, states, actions, gamma, threshold=2, test_size=0.4, multiprocessing=True)

Initialize self. See help(type(self)) for accurate signature.

_safetyTest(theta, predict=False, ub=False, est=None)

Run the safety test on the trained model from the candidate selection part i.e. the fit() function. It is also used to predict the $$g(\theta)$$ value used in candidate selection.

:param kwargs Key value arguments sent to the subclass implementation of safety test. :return Depending on the implementation, it will either return 0 if it passes or 1 if it doesn’t. Or, it will also return the $$g(\theta)$$ value if it does not pass the safety test. Use the safetyTest() method to get a boolean value.

predict(X)

Predict the output of the model on the the input X.

Parameters

X – input data to be predicted by the model.

Returns

output predictions for each sample in the input X

class seldonian.seldonian.SeldonianAlgorithmLogRegCMAES(X, y, g_hats=[], safety_data=None, verbose=False, test_size=0.35, stratify=False, hard_barrier=False, random_seed=0)

Implements a Logistic Regression classifier with CMA-ES as the optimizer using the Seldonian Approach.

__init__(X, y, g_hats=[], safety_data=None, verbose=False, test_size=0.35, stratify=False, hard_barrier=False, random_seed=0)

Initialize the model.

Parameters
• X – Training data to be used by the model.

• y – Training labels for the X

• g_hats – A list of all constraint on the model.

• safety_data – If you have a separate held out data to be used for the safety set, it should be specified here, otherwise, the data X is split according to test_size for this.

• verbose – Print out extra log statements

• test_size – ratio of the data X to e used for the safety set.

• stratify – Stratify the training data when splitting to train/safety sets.

• hard_barrier – Use a hard barrier while training the data using the BBO optimizer.

_safetyTest(theta=None, predict=False, ub=True)

Run the safety test on the trained model from the candidate selection part i.e. the fit() function. It is also used to predict the $$g(\theta)$$ value used in candidate selection.

:param kwargs Key value arguments sent to the subclass implementation of safety test. :return Depending on the implementation, it will either return 0 if it passes or 1 if it doesn’t. Or, it will also return the $$g(\theta)$$ value if it does not pass the safety test. Use the safetyTest() method to get a boolean value.

data()

Access the training data used by the model.

Returns

Tuple (Training data, labels)

predict(X)

Predict the output of the model on the the input X.

Parameters

X – input data to be predicted by the model.

Returns

output predictions for each sample in the input X

class seldonian.seldonian.SeldonianCEMPDISPolicy(data, states, actions, gamma, threshold=1.41537, test_size=0.4, verbose=False, use_ray=False)
__init__(data, states, actions, gamma, threshold=1.41537, test_size=0.4, verbose=False, use_ray=False)

Initialize self. See help(type(self)) for accurate signature.

_safetyTest(theta, predict=False, ub=False)

Run the safety test on the trained model from the candidate selection part i.e. the fit() function. It is also used to predict the $$g(\theta)$$ value used in candidate selection.

:param kwargs Key value arguments sent to the subclass implementation of safety test. :return Depending on the implementation, it will either return 0 if it passes or 1 if it doesn’t. Or, it will also return the $$g(\theta)$$ value if it does not pass the safety test. Use the safetyTest() method to get a boolean value.

data()

Access the training data used by the model.

Returns

Tuple (Training data, labels)

fit(method='Powell')

Abstract method that is used to train the model. Also, this is the candidate selection part of the Seldonian Algorithm.

Parameters

kwargs – key value arguments sent to the fit function

Returns

predict(X)

Predict the output of the model on the the input X.

Parameters

X – input data to be predicted by the model.

Returns

output predictions for each sample in the input X

class seldonian.seldonian.VanillaNN(X, y, test_size=0.4, g_hats=[], verbose=False, stratify=False, epochs=10, model=None, random_seed=0)

Implement a Seldonian Algorithm on a Neural network.

__init__(X, y, test_size=0.4, g_hats=[], verbose=False, stratify=False, epochs=10, model=None, random_seed=0)

Initialize a model with g_hats constraints. This class is an example of training a non-linear model like a neural network based on the Seldonian Approach.

Parameters
• X – Input data, this also includes the safety set.

• y – targets for the data X

• test_size – the fraction of X to be used for the safety test

• g_hats – a list of function callables that correspond to a constriant

• verbose – Set this to True to get some debug messages.

• stratify – set this to true if you want to do stratified sampling of safety set.

• epochs – number of epochs to run teh training of the model. Default: 10

• model – PyTorch model to use. Should be an instance of nn.Module. Defaults to a 2 layer model with a binary output.

_safetyTest(predict=False, ub=True)

Run the safety test on the trained model from the candidate selection part i.e. the fit() function. It is also used to predict the $$g(\theta)$$ value used in candidate selection.

:param kwargs Key value arguments sent to the subclass implementation of safety test. :return Depending on the implementation, it will either return 0 if it passes or 1 if it doesn’t. Or, it will also return the $$g(\theta)$$ value if it does not pass the safety test. Use the safetyTest() method to get a boolean value.

data()

Access the training data used by the model.

Returns

Tuple (Training data, labels)

fit(**kwargs)

Abstract method that is used to train the model. Also, this is the candidate selection part of the Seldonian Algorithm.

Parameters

kwargs – key value arguments sent to the fit function

Returns

predict(X, pmf=False)

Predict the output of the model on the the input X.

Parameters

X – input data to be predicted by the model.

Returns

output predictions for each sample in the input X

## Sample constraint functions¶

class seldonian.objectives.Constraint

Bases: abc.ABC

seldonian.objectives.ghat_recall_rate(A_idx, method='ttest', threshold=0.2)

Create a g_hat for the recall rate difference between :param A_idx subset versus the entire data.

Parameters
• A_idx

• method

• threshold – Recall rate should not be greater than this value.

Returns

method that is to be sent to the Seldonian Algorithm and is used for calculating teh g_hat

seldonian.objectives.ghat_tpr_diff(A_idx, method='ttest', threshold=0.2)

Create a $$g(\theta)$$ for the true positive rate difference between A_idx subset versus the entire data.

Parameters
• A_idx – index of the sensitive attribute in the X passed to the method returned by this function.

• method

The method used to calculate the upper bound. Currently supported values are:

• threshold – TPR rate should not be greater than this value.

Returns

method that is to be sent to the Seldonian Algorithm and is used for calculating the $$g(\theta)$$

seldonian.objectives.ghat_tpr_diff_t(A_idx, method='ttest', threshold=0.2)

Pytorch version of the true positive rate difference version of ghat_tpr_diff().

Create a $$g(\theta)$$ for the true positive rate difference between A_idx subset versus the entire data.

Parameters
• A_idx – index of the sensitive attribute in the X passed to the method returned by this function.

• method

The method used to calculate the upper bound. Currently supported values are:

• threshold – TPR rate should not be greater than this value.

Returns

method that is to be sent to the Seldonian Algorithm and is used for calculating the $$g(\theta)$$

## CMA-ES optimizer implementation¶

class seldonian.cmaes.CMAESModel(X, y, verbose=False, random_seed=0, theta=None, maxiter=None)

Bases: abc.ABC