def sobol_indices(self,
max_order=2,
S=None,
nx_samples=None,
directory_path=None,
create_plot=True,
batch_size=10):
# Computes sobol indices and generate bar plot.
# Inputs:
# Sobol_store := dictionary containing previously computed Sobol indices. The computation of
# Sobol indices is a recursive computation
# max_order := maximum order of sobol indices to compute
# nx_samples = the number of sample points for the Monte Carlo integration. Will default
# to a multiple of the number of variables if not provided
# directory_path := directory where to save the Sobol barplot if needed. Defaults to current directory
# if not specified
# create_plot := specifies if the Sobol barplot should be generated are not
# Outputs:
# Sobol := dictionary containing the Sobol indices values
if max_order > self.n_inputs:
raise Exception(
'max_order cannot be greater than the number of variables')
if self.n_inputs == 1:
print('Not enough variables to perform sensitivity analysis.')
return
if len(self.hyperpar_samples) == 0:
raise Exception(
'Hyperparameter samples must be generated or retrieved first.')
if directory_path == None:
directory_path = os.getcwd()
if not (os.path.isdir(directory_path)):
raise Exception('Invalid directory path ', directory_path)
# get list of gpu devices to parallelize computation if possible
loc_samples = self.hyperpar_samples['gp_constant_mean_function']
varm_samples = self.hyperpar_samples['kernel_variance']
beta_samples = self.hyperpar_samples['kernel_inverse_lengthscales']
varc_samples = self.hyperpar_samples['common_kernel_variance']
hyperpar_samples = [
loc_samples, varm_samples, beta_samples, varc_samples
]
if nx_samples == None:
nx_samples = 300 * self.n_inputs
selected_vars = [i for i in range(self.n_inputs)]
initial_list = sensitivity.powerset(selected_vars, 1, max_order)
subsets_list = []
if S != None:
print('Initial number of Sobol computations: ', len(initial_list))
try:
for item in initial_list:
l = sensitivity.generate_label(item, self.input_labels)
if not (l in S.keys()):
subsets_list.append(item)
print('New number of Sobol computations: ', len(subsets_list))
except Exception as e:
traceback.print_exc()
print('Invalid Sobol indices dictionary')
else:
subsets_list = initial_list
n_subset = len(subsets_list)
M = self.n_tasks
if n_subset > 0:
ybase = sensitivity.allEffect(self.model, self.Rangenorm,
nx_samples, hyperpar_samples)
ey_square = sensitivity.direct_samples(self.model, self.Rangenorm,
nx_samples,
hyperpar_samples)
ey_square = np.reshape(ey_square, (M, nx_samples, 2))
if n_subset <= batch_size:
y_higher_order = sensitivity.mainHigherOrder(
self.model, self.Rangenorm, subsets_list, nx_samples,
hyperpar_samples)
else:
y_higher_order = {}
completed = 0
n_groups = math.ceil(n_subset / batch_size)
for i in range(n_groups):
group = subsets_list[i * batch_size:(i + 1) * batch_size]
y_group = sensitivity.mainHigherOrder(
self.model, self.Rangenorm, group, nx_samples,
hyperpar_samples)
completed += len(group)
progress = 100.0 * completed / n_subset
print("Sobol indices computation: {:.2f}% complete".format(
progress))
y_higher_order.update(y_group)
e1 = np.mean(ey_square[:, :, 1] + np.square(ey_square[:, :, 0]),
axis=1)
e2 = ybase[0][0, :, 1] + np.square(ybase[0][0, :, 0])
# This will store the quantities E*[Vsub]/E*(Var(Y)) where Vsub = E[Y|Xsub] and Y is normalized
quotient_variances = {}
for idx in range(n_subset):
key = tuple(subsets_list[idx])
quotient_variances[key] = np.mean(
y_higher_order[key][:, :, 1] +
np.square(y_higher_order[key][:, :, 0]),
axis=0)
quotient_variances[key] = (quotient_variances[key] -
e2) / (e1 - e2)
if S != None:
Sobol = S
else:
Sobol = {}
for i in range(n_subset):
key = tuple(subsets_list[i])
sensitivity.compute_Sobol(Sobol, quotient_variances, key,
self.input_labels)
all_labels = list(Sobol.keys())
# plotting
n_selected = min(40, len(all_labels))
y_pos = np.arange(n_selected)
if create_plot:
si_all = {}
for j in range(M):
si_all[j] = []
for i in range(len(all_labels)):
key = all_labels[i]
si_all[j].append(Sobol[key][j])
si_all[j] = np.array(si_all[j])
order = np.argsort(-si_all[j])
selected = order[:
n_selected] # taking the top 40 values to plot
plt.figure(figsize=(12, 12))
# Create bars
plt.barh(y_pos, si_all[j][selected])
new_labels = [
all_labels[selected[i]] for i in range(n_selected)
]
title = 'top_sobol_indices_for_' + self.output_labels[j]
plt.title(title)
# Create names on the x-axis
plt.yticks(y_pos, new_labels)
figpath = title + '.png'
figpath = os.path.join(directory_path, figpath)
plt.savefig(figpath)
plt.close()
return Sobol
def group_sobol_indices(self,
max_order=2,
partition=None,
S=None,
nx_samples=None,
directory_path=None,
create_plot=True,
batch_size=10):
# Computes group sobol indices and generate bar plot.
# Inputs:
# partition := list fo lists specifying the partition of the variables
# S := dictionary containing previously computed Sobol indices. The computation of
# Sobol indices is a recursive computation
# max_order := maximum order of sobol indices to compute
# nx_samples = the number of sample points for the Monte Carlo integration. Will default
# to a multiple of the number of variables if not provided
# directory_path := directory where to save the Sobol barplot if needed. Defaults to current directory
# if not specified
# create_plot := specifies if the Sobol barplot should be generated are not
# Outputs:
# Sobol := dictionary consistsing of two main keys:
# 'mapping':= dictionary specifying the mapping between groups and variable indices
# 'results':= dictionary containing the Sobol inidces values
# label_mapping := dictionary specifying the mapping between group labels and variable labels
if S == None:
# generating the group mapping
if partition == None:
raise ValueError(
'specify a partition of the labels or provide previoulsy computed group Sobol indices dictionary'
)
groups_map = sensitivity.create_groups(partition, self.labels)
else:
groups_map = S['mapping']
n_group = len(groups_map)
if max_order > n_group:
raise Exception(
'max_order cannot be greater than the number of groups')
if n_group == 1:
print('Not enough groups to perform sensitivity analysis.')
return
if len(self.hyperpar_samples) == 0:
raise Exception(
'Hyperparameter samples must be generated or retrieved first.')
if directory_path == None:
directory_path = os.getcwd()
if not (os.path.isdir(directory_path)):
raise Exception('Invalid directory path ', directory_path)
loc_samples = self.hyperpar_samples['gp_constant_mean_function']
varm_samples = self.hyperpar_samples['kernel_variance']
beta_samples = self.hyperpar_samples['kernel_inverse_lengthscales']
hyperpar_samples = [loc_samples, varm_samples, beta_samples]
if nx_samples == None:
nx_samples = 300 * self.n_inputs
selected_groups = [i for i in range(n_group)]
initial_list = sensitivity.powerset(selected_groups, 1, max_order)
subsets_of_groups = []
if S != None:
print('Initial number of Sobol computations: ', len(initial_list))
try:
for item in initial_list:
l = sensitivity.generate_group_label(item)
if not (l in S['results'].keys()):
subsets_of_groups.append(item)
print('New number of Sobol computations: ',
len(subsets_of_groups))
except Exception as e:
traceback.print_exc()
print('Invalid Sobol indices dictionary')
else:
subsets_of_groups = initial_list
variable_subsets = []
for entry in subsets_of_groups:
variable_subsets.append(
sensitivity.get_variable_indices_list(entry, groups_map))
n_subset = len(subsets_of_groups)
if n_subset > 0:
ybase = sensitivity.allEffect(self.model, self.Rangenorm,
nx_samples, hyperpar_samples)
ey_square = sensitivity.direct_samples(self.model, self.Rangenorm,
nx_samples,
hyperpar_samples)
if n_subset <= batch_size:
y_higher_order = sensitivity.mainHigherOrder(
self.model, self.Rangenorm, variable_subsets, nx_samples,
hyperpar_samples)
else:
y_higher_order = {}
completed = 0
n_batches = math.ceil(n_subset / batch_size)
for i in range(n_batches):
batch = variable_subsets[i * batch_size:(i + 1) *
batch_size]
y_batch = sensitivity.mainHigherOrder(
self.model, self.Rangenorm, batch, nx_samples,
hyperpar_samples)
completed += len(batch)
progress = 100.0 * completed / n_subset
print("Sobol indices computation: {:.2f}% complete".format(
progress))
y_higher_order.update(y_batch)
e1 = np.mean(ey_square[:, 1] + np.square(ey_square[:, 0]))
e2 = ybase[0][0, 1] + np.square(ybase[0][0, 0])
y_higher_order_group = {}
for entry in subsets_of_groups:
subset = sensitivity.get_variable_indices_list(
entry, groups_map)
k_group = tuple(entry)
k_subset = tuple(subset)
y_higher_order_group[k_group] = y_higher_order[k_subset]
quotient_variances = {}
for entry in subsets_of_groups:
k_group = tuple(entry)
quotient_variances[k_group] = np.mean(
y_higher_order_group[k_group][:, 1] +
np.square(y_higher_order_group[k_group][:, 0]))
quotient_variances[k_group] = (quotient_variances[k_group] -
e2) / (e1 - e2)
if S != None:
Sobol = S
else:
Sobol = {}
Sobol['mapping'] = groups_map
Sobol['results'] = {}
for i in range(n_subset):
key = tuple(subsets_of_groups[i])
sensitivity.compute_group_Sobol(Sobol['results'],
quotient_variances, key)
all_labels = list(Sobol['results'].keys())
si_all = list(Sobol['results'].values())
# plotting
si_all = np.array(si_all)
order = np.argsort(-si_all)
n_selected = min(40, len(si_all))
selected = order[:n_selected] # taking the top 40 values to plot
y_pos = np.arange(n_selected)
if create_plot:
print('Generating group Sobol indices barplot.')
plt.figure(figsize=(12, 12))
# Create bars
plt.barh(y_pos, si_all[selected])
new_labels = [all_labels[selected[i]] for i in range(n_selected)]
title = 'top_group_sobol_indices'
plt.title(title)
# Create names on the x-axis
plt.yticks(y_pos, new_labels)
figpath = title + '.png'
figpath = os.path.join(directory_path, figpath)
plt.savefig(figpath)
plt.close()
# generate label_mapping
label_mapping = {}
for k in groups_map:
label_mapping[k] = [self.labels[i] for i in groups_map[k]]
return Sobol, label_mapping