def test_risk_slim(data_csv_file,
sample_weights_csv_file=None,
max_coefficient=5,
max_L0_value=5,
max_offset=50,
c0_value=1e-6,
w_pos=1.00,
settings=None):
# load dataset
data = load_data_from_csv(dataset_csv_file=data_csv_file,
sample_weights_csv_file=sample_weights_csv_file)
N, P = data['X'].shape
# offset value
coef_set = CoefficientSet(variable_names=data['variable_names'],
lb=-max_coefficient,
ub=max_coefficient,
sign=0)
conservative_offset = get_conservative_offset(data, coef_set, max_L0_value)
max_offset = min(max_offset, conservative_offset)
coef_set['(Intercept)'].ub = max_offset
coef_set['(Intercept)'].lb = -max_offset
# create constraint dictionary
trivial_L0_max = P - np.sum(coef_set.C_0j == 0)
max_L0_value = min(max_L0_value, trivial_L0_max)
constraints = {
'L0_min': 0,
'L0_max': max_L0_value,
'coef_set': coef_set,
}
# Train model using lattice_cpa
model_info, mip_info, lcpa_info = run_lattice_cpa(data, constraints,
settings)
#model info contains key results
pprint(model_info)
# lcpa_output contains detailed information about LCPA
pprint(lcpa_info)
# todo check solution
# mip_output contains information to access the MIP
mip_info['risk_slim_mip'] #CPLEX mip
mip_info['risk_slim_idx'] #indices of the relevant constraints
return True
# problem parameters
max_coefficient = 5 # value of largest/smallest coefficient
max_L0_value = 5 # maximum model size
max_offset = 50 # maximum value of offset parameter (optional)
c0_value = 1e-6 # L0-penalty parameter such that c0_value > 0; larger values -> sparser models; we set to a small value (1e-6) so that we get a model with max_L0_value terms
w_pos = 1.00 # relative weight on examples with y = +1; w_neg = 1.00 (optional)
# load dataset
data = load_data_from_csv(dataset_csv_file = data_csv_file, sample_weights_csv_file = sample_weights_csv_file)
# coefficient set
coef_set = CoefficientSet(variable_names = data['variable_names'], lb=-max_coefficient, ub=max_coefficient, sign=0)
# offset value
conservative_offset = get_conservative_offset(data, coef_set, max_L0_value)
conservative_offset = get_conservative_offset(data, coef_set, max_L0_value)
max_offset = min(max_offset, conservative_offset)
coef_set['(Intercept)'].ub = max_offset
coef_set['(Intercept)'].lb = -max_offset
# create constraint dictionary
trivial_L0_max = P - np.sum(coef_set.C_0j == 0)
max_L0_value = min(max_L0_value, trivial_L0_max)
constraints = {
'L0_min': 0,
'L0_max': max_L0_value,
'coef_set': coef_set,
}
def risk_slim(data, max_coefficient, max_L0_value, c0_value, max_offset, max_runtime = 120, w_pos = 1):
"""
@parameters:
max_coefficient: value of largest/smallest coefficient
max_L0_value: maximum model size (set as float(inf))
max_offset: maximum value of offset parameter (optional)
c0_value: L0-penalty parameter such that c0_value > 0; larger values ->
sparser models; we set to a small value (1e-6) so that we get a model with max_L0_value terms
max_runtime: max algorithm running time
w_pos: relative weight on examples with y = +1; w_neg = 1.00 (optional)
"""
# create coefficient set and set the value of the offset parameter
coef_set = CoefficientSet(variable_names = data['variable_names'], lb = -max_coefficient, ub = max_coefficient, sign = 0)
conservative_offset = get_conservative_offset(data, coef_set, max_L0_value)
max_offset = min(max_offset, conservative_offset)
coef_set['(Intercept)'].ub = max_offset
coef_set['(Intercept)'].lb = -max_offset
constraints = {
'L0_min': 0,
'L0_max': max_L0_value,
'coef_set':coef_set,
}
# Set parameters
settings = {
# Problem Parameters
'c0_value': c0_value,
'w_pos': w_pos,
# LCPA Settings
'max_runtime': max_runtime, # max runtime for LCPA
'max_tolerance': np.finfo('float').eps, # tolerance to stop LCPA (set to 0 to return provably optimal solution)
'display_cplex_progress': True, # print CPLEX progress on screen
'loss_computation': 'lookup', # how to compute the loss function ('normal','fast','lookup')
# LCPA Improvements
'round_flag': False, # round continuous solutions with SeqRd
'polish_flag': False, # polish integer feasible solutions with DCD
'chained_updates_flag': False, # use chained updates
'add_cuts_at_heuristic_solutions': True, # add cuts at integer feasible solutions found using polishing/rounding
# Initialization
'initialization_flag': True, # use initialization procedure
'init_max_runtime': 300.0, # max time to run CPA in initialization procedure
'init_max_coefficient_gap': 0.49,
# CPLEX Solver Parameters
'cplex_randomseed': 0, # random seed
'cplex_mipemphasis': 0, # cplex MIP strategy
}
# train model using lattice_cpa
model_info, mip_info, lcpa_info = run_lattice_cpa(data, constraints, settings)
return model_info, mip_info, lcpa_info
# initialize coefficient set and offset parameter
logger.info("creating coefficient set and constraints")
max_coefficient = parsed.max_coef
max_model_size = parsed.max_size if parsed.max_size >= 0 else float('inf')
max_offset = parsed.max_offset if parsed.max_offset >= 0 else float('inf')
coef_set = CoefficientSet(variable_names=data['variable_names'],
lb=-max_coefficient,
ub=max_coefficient,
sign=0)
trivial_model_size = P - np.sum(coef_set.C_0j == 0)
max_model_size = min(max_model_size, trivial_model_size)
conservative_offset = get_conservative_offset(data, coef_set,
max_model_size)
max_offset = min(max_offset, conservative_offset)
coef_set['(Intercept)'].ub = max_offset
coef_set['(Intercept)'].lb = -max_offset
#print coefficient set
if not parsed.silent:
coef_set.view()
constraints = {
'L0_min': 0,
'L0_max': max_model_size,
'coef_set': coef_set,
}
# fit RiskSLIM model using Lattice Cutting Plane Algorithm
def fit(self, X, y):
X, y = check_X_y(X, y, accept_sparse=True)
self.is_fitted_ = True
# transforming data
raw_data = np.insert(X, 0, y, axis=1)
N = raw_data.shape[0]
# setup Y vector and Y_name
Y_col_idx = [0]
Y = raw_data[:, Y_col_idx]
Y_name = self.data_headers[Y_col_idx[0]]
Y[Y == 0] = -1
# setup X and X_names
X_col_idx = [j for j in range(raw_data.shape[1]) if j not in Y_col_idx]
X = raw_data[:, X_col_idx]
variable_names = [self.data_headers[j] for j in X_col_idx]
# insert a column of ones to X for the intercept
X = np.insert(arr=X, obj=0, values=np.ones(N), axis=1)
variable_names.insert(0, '(Intercept)')
if self.sample_weights is None or len(self.sample_weights) != N:
self.sample_weights = np.ones(N)
self.data = {
'X': X,
'Y': Y,
'variable_names': variable_names,
'outcome_name': Y_name,
'sample_weights': self.sample_weights,
}
#load folds
if self.fold_csv_file is not None:
if not os.path.isfile(self.fold_csv_file):
raise IOError('could not find fold_csv_file: %s' %
self.fold_csv_file)
else:
fold_idx = pd.read_csv(self.fold_csv_file,
sep=',',
header=None)
fold_idx = fold_idx.values.flatten()
K = max(fold_idx)
all_fold_nums = np.sort(np.unique(fold_idx))
assert len(
fold_idx
) == N, "dimension mismatch: read %r fold indices (expected N = %r)" % (
len(fold_idx), N)
assert np.all(all_fold_nums == np.arange(
1, K +
1)), "folds should contain indices between 1 to %r" % K
assert fold_num in np.arange(
0, K + 1
), "fold_num should either be 0 or an integer between 1 to %r" % K
if fold_num >= 1:
test_idx = fold_num == fold_idx
train_idx = fold_num != fold_idx
data['X'] = data['X'][train_idx, ]
data['Y'] = data['Y'][train_idx]
data['sample_weights'] = data['sample_weights'][train_idx]
assert check_data(self.data)
# create coefficient set and set the value of the offset parameter
coef_set = CoefficientSet(variable_names=self.data['variable_names'],
lb=-self.max_coefficient,
ub=self.max_coefficient,
sign=0)
conservative_offset = get_conservative_offset(self.data, coef_set,
self.max_L0_value)
self.max_offset = min(self.max_offset, conservative_offset)
coef_set['(Intercept)'].ub = self.max_offset
coef_set['(Intercept)'].lb = -self.max_offset
# edit contraints here
constraints = {
'L0_min': 0,
'L0_max': self.max_L0_value,
'coef_set': coef_set,
}
# initialize MIP for lattice CPA
mip_objects = setup_lattice_cpa(self.data, constraints, self.settings)
# add operational constraints
mip = mip_objects['mip']
indices = mip_objects['indices']
get_alpha_name = lambda var_name: 'alpha_' + str(self.data[
'variable_names'].index(var_name))
get_alpha_ind = lambda var_names: [
get_alpha_name(v) for v in var_names
]
# applies mutual exclusivity feature contraints
if self.op_constraints is not None:
names = []
expressions = []
for key in self.op_constraints.keys():
names.append("mutually_exclusive_%s" % key)
expressions.append(
cplex.SparsePair(
ind=get_alpha_ind(self.op_constraints[key]),
val=[1.0] * len(self.op_constraints[key])))
mip.linear_constraints.add(
names=names,
lin_expr=expressions,
senses=["L"] * len(self.op_constraints.keys()),
rhs=[1.0] * len(self.op_constraints.keys()))
mip_objects['mip'] = mip
# fit using ltca
model_info, mip_info, lcpa_info = finish_lattice_cpa(
self.data, constraints, mip_objects, self.settings)
rho = model_info['solution']
self.model_info = model_info
if np.sum(rho[1:]) != 0:
print_model(model_info['solution'], self.data)
print("solver_time = %d" % model_info['solver_time'])
print("optimality_gap = %.3f" % model_info['optimality_gap'])
print(rho)
variable_names = self.data['variable_names']
rho_values = np.copy(rho)
rho_names = list(variable_names)
# removes intercept value or sets it to 0
if '(Intercept)' in rho_names:
intercept_ind = variable_names.index('(Intercept)')
self.intercept_val = int(rho[intercept_ind])
rho_values = np.delete(rho_values, intercept_ind)
rho_names.remove('(Intercept)')
else:
self.intercept_val = 0
self.filter_mask = np.array(rho_values) != 0
# removes zero values
if not self.show_omitted_variables:
selected_ind = np.flatnonzero(rho_values)
self.rho_values = rho_values[selected_ind]
self.rho_names = [rho_names[i] for i in selected_ind]
return self
