Source code for openmdao.components.meta_model_semi_structured_comp

"""Define the MetaModelSemiStructuredComp class."""
import inspect

import numpy as np

from openmdao.components.interp_util.outofbounds_error import OutOfBoundsError
from openmdao.components.interp_util.interp_semi import InterpNDSemi, TABLE_METHODS
from openmdao.core.analysis_error import AnalysisError
from openmdao.core.explicitcomponent import ExplicitComponent

[docs]class MetaModelSemiStructuredComp(ExplicitComponent): """ Interpolation Component generated from semi-structured data on a regular grid. Produces smooth fits through provided training data using polynomial splines of various orders. Analytic derivatives are automatically computed. For multi-dimensional data, fits are computed on a separable per-axis basis. If a particular dimension does not have enough training data points to support a selected spline method (e.g. 3 sample points, but an fifth order quintic spline is specified) the order of the fitted spline with be automatically reduced for that dimension alone. Extrapolation is supported, but disabled by default. It can be enabled via initialization option. Attributes ---------- interps : dict Dictionary of interpolations for each output. pnames : list Cached list of input names. training_inputs : dict of ndarray Dictionary of grid point locations corresponding to the training values in self.training_outputs. training_outputs : dict of ndarray Dictionary of training data each output. """
[docs] def __init__(self, **kwargs): """ Initialize all attributes. Parameters ---------- **kwargs : dict of keyword arguments Keyword arguments that will be mapped into the Component options. """ super().__init__(**kwargs) self.pnames = [] self.training_inputs = {} self.training_outputs = {} self.interps = {} self._no_check_partials = True
[docs] def initialize(self): """ Initialize the component. """ self.options.declare('extrapolate', types=bool, default=True, desc='Sets whether extrapolation should be performed ' 'when an input is out of bounds.') self.options.declare('training_data_gradients', types=bool, default=False, desc='When True, compute gradients with respect to training data ' 'values.') self.options.declare('vec_size', types=int, default=1, desc='Number of points to evaluate at once.') self.options.declare('method', values=TABLE_METHODS, default='slinear', desc='Spline interpolation method to use for all outputs.')
[docs] def add_input(self, name, training_data, val=1.0, **kwargs): """ Add an input to this component and a corresponding training input. Parameters ---------- name : string Name of the input. training_data : ndarray Training data grid sample points for this input variable. Must be of length m, where m is the total number of points in the table.. val : float or ndarray Initial value for the input. **kwargs : dict Additional agruments for add_input. """ n = self.options['vec_size'] # Currently no support for vector inputs, apart from vec_size if not np.isscalar(val): if len(val) not in [1, n] or len(val.shape) > 1: msg = "{}: Input {} must either be scalar, or of length equal to vec_size." raise ValueError(msg.format(self.msginfo, name)) super().add_input(name, val * np.ones(n), **kwargs) self.training_inputs[name] = training_data self.pnames.append(name)
[docs] def add_output(self, name, training_data, **kwargs): """ Add an output to this component and a corresponding training output. Parameters ---------- name : string Name of the output. training_data : ndarray Training data sample points for this output variable. Must be of length m, where m is the total number of points in the table. **kwargs : dict Additional agruments for add_output. """ n = self.options['vec_size'] super().add_output(name, np.ones(n), **kwargs) self.training_outputs[name] = training_data if self.options['training_data_gradients']: super().add_input("%s_train" % name, val=training_data, **kwargs)
def _setup_var_data(self): """ Instantiate surrogates for the output variables that use the default surrogate. """ interp_method = self.options['method'] # Make sure all training data is sized correctly. size = len(self.training_inputs[self.pnames[0]]) for data_dict in [self.training_inputs, self.training_outputs]: for name, data in data_dict.items(): size2 = len(data) if size2 != size: msg = f"Size mismatch: training data for '{name}' is length {size2}, but" + \ f" data for '{self.pnames[0]}' is length {size}." raise ValueError(msg) grid = np.array([col for col in self.training_inputs.values()]).T for name, train_data in self.training_outputs.items(): self.interps[name] = InterpNDSemi(grid, train_data, method=interp_method, extrapolate=self.options['extrapolate']) super()._setup_var_data() def _setup_partials(self): """ Process all partials and approximations that the user declared. Metamodel needs to declare its partials after inputs and outputs are known. """ super()._setup_partials() arange = np.arange(self.options['vec_size']) pnames = tuple(self.pnames) dct = { 'rows': arange, 'cols': arange, 'dependent': True, } for name in self._var_rel_names['output']: self._declare_partials(of=name, wrt=pnames, dct=dct) if self.options['training_data_gradients']: self._declare_partials(of=name, wrt="%s_train" % name, dct={'dependent': True}) # The scipy methods do not support complex step. if self.options['method'].startswith('scipy'): self.set_check_partial_options('*', method='fd')
[docs] def compute(self, inputs, outputs): """ Perform the interpolation at run time. Parameters ---------- inputs : Vector unscaled, dimensional input variables read via inputs[key] outputs : Vector unscaled, dimensional output variables read via outputs[key] """ pt = np.array([inputs[pname].ravel() for pname in self.pnames]).T for out_name, interp in self.interps.items(): if self.options['training_data_gradients']: # Training point values may have changed every time we compute. interp.values = inputs["%s_train" % out_name] interp._compute_d_dvalues = True try: val = interp._interpolate(pt) except OutOfBoundsError as err: varname_causing_error = '.'.join((self.pathname, self.pnames[err.idx])) errmsg = (f"{self.msginfo}: Error interpolating output '{out_name}' " f"because input '{varname_causing_error}' required extrapolation while " f"interpolating dimension {err.idx + 1}, where its value '{err.value}'" f" exceeded the range ('{ err.lower}', '{err.upper}')") raise AnalysisError(errmsg, inspect.getframeinfo(inspect.currentframe()), self.msginfo) except ValueError as err: raise ValueError(f"{self.msginfo}: Error interpolating output '{out_name}':\n" f"{str(err)}") outputs[out_name] = val
[docs] def compute_partials(self, inputs, partials): """ Collect computed partial derivatives and return them. Checks if the needed derivatives are cached already based on the inputs vector. Refreshes the cache by re-computing the current point if necessary. Parameters ---------- inputs : Vector unscaled, dimensional input variables read via inputs[key] partials : Jacobian sub-jac components written to partials[output_name, input_name] """ pt = np.array([inputs[pname].ravel() for pname in self.pnames]).T for out_name, interp in self.interps.items(): dval = interp.gradient(pt).T for i, p in enumerate(self.pnames): partials[out_name, p] = dval[i, :] if self.options['training_data_gradients']: train_name = f"{out_name}_train" d_dvalues = interp._d_dvalues partials[out_name, train_name] = d_dvalues