def eval_min(
model,
out_min=None,
out_geq=None,
out_leq=None,
out_eq=None,
method="SLSQP",
tol=1e-6,
n_restart=1,
n_maxiter=50,
seed=None,
df_start=None,
):
r"""Constrained minimization using functions from a model
Perform constrained minimization using functions from a model. Model must
have deterministic variables only.
Wrapper for scipy.optimize.minimize
Args:
model (gr.Model): Model to analyze. All model variables must be
deterministic.
out_min (str): Output to use as minimization objective.
out_geq (None OR list of str): Outputs to use as geq constraints; out >= 0
out_leq (None OR list of str): Outputs to use as leq constraints; out <= 0
out_eq (None OR list of str): Outputs to use as equality constraints; out == 0
method (str): Optimization method; see the documentation for
scipy.optimize.minimize for options.
tol (float): Optimization objective convergence tolerance
n_restart (int): Number of restarts; beyond n_restart=1 random
restarts are used.
df_start (None or DataFrame): Specific starting values to use; overrides
n_restart if non None provided.
Returns:
DataFrame: Results of optimization
Examples:
>>> import grama as gr
>>> md = (
>>> gr.Model("Constrained Rosenbrock")
>>> >> gr.cp_function(
>>> fun=lambda x: (1 - x[0])**2 + 100*(x[1] - x[0]**2)**2,
>>> var=["x", "y"],
>>> out=["c"],
>>> )
>>> >> gr.cp_function(
>>> fun=lambda x: (x[0] - 1)**3 - x[1] + 1,
>>> var=["x", "y"],
>>> out=["g1"],
>>> )
>>> >> gr.cp_function(
>>> fun=lambda x: x[0] + x[1] - 2,
>>> var=["x", "y"],
>>> out=["g2"],
>>> )
>>> >> gr.cp_bounds(
>>> x=(-1.5, +1.5),
>>> y=(-0.5, +2.5),
>>> )
>>> )
>>> md >> gr.ev_min(
>>> out_min="c",
>>> out_leq=["g1", "g2"]
>>> )
"""
## Check that model has only deterministic variables
if model.n_var_rand > 0:
raise ValueError("model must have no random variables")
## Check that objective is in model
if not (out_min in model.out):
raise ValueError("model must contain out_min")
## Check that constraints are in model
if not (out_geq is None):
out_diff = set(out_geq).difference(set(model.out))
if len(out_diff) > 0:
raise ValueError(
"model must contain each out_geq; missing {}".format(out_diff))
if not (out_leq is None):
out_diff = set(out_leq).difference(set(model.out))
if len(out_diff) > 0:
raise ValueError(
"model must contain each out_leq; missing {}".format(out_diff))
if not (out_eq is None):
out_diff = set(out_eq).difference(set(model.out))
if len(out_diff) > 0:
raise ValueError(
"model must contain each out_eq; missing {}".format(out_diff))
## Formulate initial guess
df_nom = eval_nominal(model, df_det="nom", skip=True)
if df_start is None:
df_start = df_nom[model.var]
if n_restart > 1:
if not (seed is None):
setseed(seed)
## Collect sweep-able deterministic variables
var_sweep = list(
filter(
lambda v: isfinite(model.domain.get_width(v))
& (model.domain.get_width(v) > 0),
model.var_det,
))
## Generate pseudo-marginals
dicts_var = {}
for v in var_sweep:
dicts_var[v] = {
"dist": "uniform",
"loc": model.domain.get_bound(v)[0],
"scale": model.domain.get_width(v),
}
## Overwrite model
md_sweep = comp_marginals(model, **dicts_var)
md_sweep = comp_copula_independence(md_sweep)
## Generate random start points
df_rand = eval_sample(
md_sweep,
n=n_restart - 1,
df_det="nom",
skip=True,
)
df_start = concat((df_start, df_rand[model.var]),
axis=0).reset_index(drop=True)
else:
n_restart = df_start.shape[0]
## Factory for wrapping model's output
def make_fun(out, sign=+1):
def fun(x):
df = DataFrame([x], columns=model.var)
df_res = eval_df(model, df)
return sign * df_res[out]
return fun
## Create helper functions for constraints
constraints = []
if not (out_geq is None):
for out in out_geq:
constraints.append({
"type": "ineq",
"fun": make_fun(out),
})
if not (out_leq is None):
for out in out_leq:
constraints.append({
"type": "ineq",
"fun": make_fun(out, sign=-1),
})
if not (out_eq is None):
for out in out_eq:
constraints.append({
"type": "eq",
"fun": make_fun(out),
})
## Parse the bounds for minimize
bounds = list(map(lambda k: model.domain.bounds[k], model.var))
## Run optimization
df_res = DataFrame()
for i in range(n_restart):
x0 = df_start[model.var].iloc[i].values
res = minimize(
make_fun(out_min),
x0,
args=(),
method=method,
jac=False,
tol=tol,
options={
"maxiter": n_maxiter,
"disp": False
},
constraints=constraints,
bounds=bounds,
)
df_opt = df_make(
**dict(zip(model.var, res.x)),
**dict(zip(map(lambda s: s + "_0", model.var), x0)),
)
df_tmp = eval_df(model, df=df_opt)
df_tmp["success"] = [res.success]
df_tmp["message"] = [res.message]
df_tmp["n_iter"] = [res.nit]
df_res = concat((df_res, df_tmp), axis=0).reset_index(drop=True)
return df_res
def eval_sinews(
model,
n_density=10,
n_sweeps=3,
seed=None,
df_det=None,
varname="sweep_var",
indname="sweep_ind",
append=True,
skip=False,
):
r"""Sweep study
Perform coordinate sweeps over each model random variable ("sinew" design). Use random starting points drawn from the joint density. Optionally sweep the deterministic variables.
For more expensive models, it can be helpful to tune n_density and n_sweeps to achieve a reasonable runtime.
Use gr.plot_auto() to construct a quick visualization of the output dataframe. Use `skip` version to visualize the design, and non-skipped version to visualize the results.
Args:
model (gr.Model): Model to evaluate
n_density (numeric): Number of points along each sweep
n_sweeps (numeric): Number of sweeps per-random variable
seed (int): Random seed to use
df_det (DataFrame): Deterministic levels for evaluation;
use "nom" for nominal deterministic levels,
use "swp" to sweep deterministic variables
varname (str): Column name to give for sweep variable; default="sweep_var"
indname (str): Column name to give for sweep index; default="sweep_ind"
append (bool): Append results to conservative inputs?
skip (bool): Skip evaluation of the functions?
Returns:
DataFrame: Results of evaluation or unevaluated design
Examples:
>>> import grama as gr
>>> md = gr.make_cantilever_beam()
>>> # Skip evaluation, vis. design
>>> df_design = md >> gr.ev_sinews(df_det="nom", skip=True)
>>> df_design >> gr.pt_auto()
>>> # Vis results
>>> df_sinew = md >> gr.ev_sinews(df_det="nom")
>>> df_sinew >> gr.pt_auto()
"""
## Override model if deterministic sweeps desired
if df_det == "swp":
## Collect sweep-able deterministic variables
var_sweep = list(
filter(
lambda v: isfinite(model.domain.get_width(v))
& (model.domain.get_width(v) > 0),
model.var_det,
))
## Generate pseudo-marginals
dicts_var = {}
for v in var_sweep:
dicts_var[v] = {
"dist": "uniform",
"loc": model.domain.get_bound(v)[0],
"scale": model.domain.get_width(v),
}
## Overwrite model
model = comp_marginals(model, **dicts_var)
## Restore flag
df_det = "nom"
## Set seed only if given
if seed is not None:
set_seed(seed)
## Ensure sample count is int
if not isinstance(n_density, Integral):
print("eval_sinews() is rounding n_density...")
n_density = int(n_density)
if not isinstance(n_sweeps, Integral):
print("eval_sinews() is rounding n_sweeps...")
n_sweeps = int(n_sweeps)
## Build quantile sweep data
q_random = tile(random((1, model.n_var_rand, n_sweeps)), (n_density, 1, 1))
q_dense = linspace(0, 1, num=n_density)
Q_all = zeros((n_density * n_sweeps * model.n_var_rand, model.n_var_rand))
C_var = ["tmp"] * (n_density * n_sweeps * model.n_var_rand)
C_ind = [0] * (n_density * n_sweeps * model.n_var_rand)
## Interlace
for i_input in range(model.n_var_rand):
ind_base = i_input * n_density * n_sweeps
for i_sweep in range(n_sweeps):
ind_start = ind_base + i_sweep * n_density
ind_end = ind_base + (i_sweep + 1) * n_density
Q_all[ind_start:ind_end] = q_random[:, :, i_sweep]
Q_all[ind_start:ind_end, i_input] = q_dense
C_var[ind_start:ind_end] = [model.var_rand[i_input]] * n_density
C_ind[ind_start:ind_end] = [i_sweep] * n_density
## Modify endpoints for infinite support
if not isfinite(
model.density.marginals[model.var_rand[i_input]].q(0)):
Q_all[ind_start, i_input] = 1 / n_density / 10
if not isfinite(
model.density.marginals[model.var_rand[i_input]].q(1)):
Q_all[ind_end - 1, i_input] = 1 - 1 / n_density / 10
## Assemble sampling plan
df_pr = DataFrame(data=Q_all, columns=model.var_rand)
df_rand = model.density.pr2sample(df_pr)
df_rand[varname] = C_var
df_rand[indname] = C_ind
## Construct outer-product DOE
df_samp = model.var_outer(df_rand, df_det=df_det)
if skip:
## Evaluation estimate
runtime_est = model.runtime(df_samp.shape[0])
if runtime_est > 0:
print(
"Estimated runtime for design with model ({0:1}):\n {1:4.3} sec"
.format(model.name, runtime_est))
else:
print(
"Design runtime estimates unavailable; model has no timing data."
)
## For autoplot
with catch_warnings():
simplefilter("ignore")
df_samp._plot_info = {
"type": "sinew_inputs",
"var": model.var_rand
}
## Pass-through
return df_samp
## Apply
df_res = eval_df(model, df=df_samp, append=append)
## For autoplot
with catch_warnings():
simplefilter("ignore")
df_res._plot_info = {
"type": "sinew_outputs",
"var": model.var_rand,
"out": model.out,
}
return df_res
def eval_nls(
model,
df_data=None,
out=None,
var_fix=None,
df_init=None,
append=False,
tol=1e-6,
ftol=1e-9,
gtol=1e-5,
n_maxiter=100,
n_restart=1,
n_process=1,
method="L-BFGS-B",
seed=None,
verbose=True,
):
r"""Estimate with Nonlinear Least Squares (NLS)
Estimate best-fit variable levels with nonlinear least squares (NLS).
Args:
model (gr.Model): Model to analyze. All model variables
selected for fitting must be bounded or random. Deterministic
variables may have semi-infinite bounds.
df_data (DataFrame): Data for estimating parameters. Variables not
found in df_data optimized in fitting.
out (list or None): Output contributions to consider in computing MSE.
Assumed to be model.out if left as None.
var_fix (list or None): Variables to fix to nominal levels. Note that
variables with domain width zero will automatically be fixed.
df_init (DataFrame): Initial guesses for parameters; overrides n_restart
append (bool): Append metadata? (Initial guess, MSE, optimizer status)
tol (float): Optimizer convergence tolerance
n_maxiter (int): Optimizer maximum iterations
n_restart (int): Number of restarts; beyond n_restart=1 random
restarts are used.
seed (int OR None): Random seed for restarts
verbose (bool): Print messages to console?
Returns:
DataFrame: Results of estimation
Examples:
>>> import grama as gr
>>> from grama.data import df_trajectory_full
>>> from grama.models import make_trajectory_linear
>>>
>>> md_trajectory = make_trajectory_linear()
>>>
>>> df_fit = (
>>> md_trajectory
>>> >> gr.ev_nls(df_data=df_trajectory_full)
>>> )
>>>
>>> print(df_fit)
"""
## Check `out` invariants
if out is None:
out = model.out
if verbose:
print("... eval_nls setting out = {}".format(out))
set_diff = set(out).difference(set(df_data.columns))
if len(set_diff) > 0:
raise ValueError("out must be subset of df_data.columns\n" +
"difference = {}".format(set_diff))
## Determine variables to be fixed
if var_fix is None:
var_fix = set()
else:
var_fix = set(var_fix)
for var in model.var_det:
wid = model.domain.get_width(var)
if wid == 0:
var_fix.add(var)
if verbose:
print("... eval_nls setting var_fix = {}".format(list(var_fix)))
var_fix = list(var_fix)
## Determine variables for evaluation
var_feat = set(model.var).intersection(set(df_data.columns))
if verbose:
print("... eval_nls setting var_feat = {}".format(var_feat))
var_feat = list(var_feat)
## Determine variables for fitting
var_fit = set(model.var).difference(set(var_fix).union(set(var_feat)))
if len(var_fit) == 0:
raise ValueError("No var selected for fitting!\n" +
"Try checking model bounds and df_data.columns.")
var_fit = list(var_fit)
## Separate var_fit into det and rand
var_fit_det = list(set(model.var_det).intersection(var_fit))
var_fit_rand = list(set(model.var_rand).intersection(var_fit))
## Construct bounds, fix var_fit order
var_fit = var_fit_det + var_fit_rand
bounds = []
var_prob = []
for var in var_fit_det:
if not isfinite(model.domain.get_nominal(var)):
var_prob.append(var)
bounds.append(model.domain.get_bound(var))
if len(var_prob) > 0:
raise ValueError(
"all variables to be fitted must finite nominal value\n" +
"offending var = {}".format(var_prob))
for var in var_fit_rand:
bounds.append((
model.density.marginals[var].q(0),
model.density.marginals[var].q(1),
))
## Determine initial guess points
df_nom = eval_nominal(model, df_det="nom", skip=True)
## Use specified initial guess(es)
if not (df_init is None):
# Check invariants
set_diff = list(set(var_fit).difference(set(df_init.columns)))
if len(set_diff) > 0:
raise ValueError("var_fit must be subset of df_init.columns\n" +
"difference = {}".format(set_diff))
# Pull n_restart
n_restart = df_init.shape[0]
## Generate initial guess(es)
else:
df_init = df_nom[var_fit]
if n_restart > 1:
if not (seed is None):
setseed(seed)
## Collect sweep-able deterministic variables
var_sweep = list(
filter(
lambda v: isfinite(model.domain.get_width(v))
& (model.domain.get_width(v) > 0),
model.var_det,
))
## Generate pseudo-marginals
dicts_var = {}
for v in var_sweep:
dicts_var[v] = {
"dist": "uniform",
"loc": model.domain.get_bound(v)[0],
"scale": model.domain.get_width(v),
}
## Overwrite model
md_sweep = comp_marginals(model, **dicts_var)
md_sweep = comp_copula_independence(md_sweep)
## Generate random start points
df_rand = eval_sample(
md_sweep,
n=n_restart - 1,
df_det="nom",
skip=True,
)
df_init = concat((df_init, df_rand[var_fit]),
axis=0).reset_index(drop=True)
## Iterate over initial guesses
df_res = DataFrame()
def fun_mp(i):
x0 = df_init[var_fit].iloc[i].values
## Build evaluator
def objective(x):
"""x = [var_fit]"""
## Evaluate model
df_var = tran_outer(
df_data[var_feat],
concat(
(df_nom[var_fix].iloc[[0]],
df_make(**dict(zip(var_fit, x)))),
axis=1,
),
)
df_tmp = eval_df(model, df=df_var)
## Compute joint MSE
return ((df_tmp[out].values - df_data[out].values)**2).mean()
## Run optimization
res = minimize(
objective,
x0,
args=(),
method=method,
jac=False,
tol=tol,
options={
"maxiter": n_maxiter,
"disp": False,
"ftol": ftol,
"gtol": gtol,
},
bounds=bounds,
)
df_tmp = df_make(
**dict(zip(var_fit, res.x)),
**dict(zip(map(lambda s: s + "_0", var_fit), x0)),
)
df_tmp["success"] = [res.success]
df_tmp["message"] = [res.message]
df_tmp["n_iter"] = [res.nit]
df_tmp["mse"] = [res.fun]
return df_tmp
df_res = DataFrame()
for i in range(n_restart):
df_tmp = fun_mp(i)
df_res = concat((df_res, df_tmp), axis=0).reset_index(drop=True)
## Post-process
if append:
return df_res
return df_res[var_fit]
