pyemma.thermo.WHAM¶
-
class
pyemma.thermo.
WHAM
(bias_energies_full, maxiter=10000, maxerr=1e-15, save_convergence_info=0, dt_traj='1 step', stride=1)¶ Weighted Histogram Analysis Method.
-
__init__
(bias_energies_full, maxiter=10000, maxerr=1e-15, save_convergence_info=0, dt_traj='1 step', stride=1)¶ Weighted Histogram Analysis Method
Parameters: - bias_energies_full (numpy.ndarray(shape=(num_therm_states, num_conf_states)) object) – bias_energies_full[j, i] is the bias energy in units of kT for each discrete state i at thermodynamic state j.
- maxiter (int, optional, default=10000) – The maximum number of self-consistent iterations before the estimator exits unsuccessfully.
- maxerr (float, optional, default=1.0E-15) – Convergence criterion based on the maximal free energy change in a self-consistent iteration step.
- save_convergence_info (int, optional, default=0) – Every save_convergence_info iteration steps, store the actual increment and the actual loglikelihood; 0 means no storage.
- dt_traj (str, optional, default='1 step') –
Description of the physical time corresponding to the lag. May be used by analysis algorithms such as plotting tools to pretty-print the axes. By default ‘1 step’, i.e. there is no physical time unit. Specify by a number, whitespace and unit. Permitted units are (* is an arbitrary string):
‘fs’, ‘femtosecond*’‘ps’, ‘picosecond*’‘ns’, ‘nanosecond*’‘us’, ‘microsecond*’‘ms’, ‘millisecond*’‘s’, ‘second*’ - stride (int, optional, default=1) – not used
Example
>>> from pyemma.thermo import WHAM >>> import numpy as np >>> B = np.array([[0, 0],[0.5, 1.0]]) >>> wham = WHAM(B) >>> ttrajs = [np.array([0,0,0,0,0,0,0,0,0,0]),np.array([1,1,1,1,1,1,1,1,1,1])] >>> dtrajs = [np.array([0,0,0,0,1,1,1,0,0,0]),np.array([0,1,0,1,0,1,1,0,0,1])] >>> wham = wham.estimate((ttrajs, dtrajs)) >>> wham.log_likelihood() -6.6... >>> wham.state_counts array([[7, 3], [5, 5]]) >>> wham.stationary_distribution array([ 0.5..., 0.4...]) >>> wham.meval('stationary_distribution') [array([ 0.5..., 0.4...]), array([ 0.6..., 0.3...])]
References
[1] Ferrenberg, A.M. and Swensen, R.H. 1988. New Monte Carlo Technique for Studying Phase Transitions. Phys. Rev. Lett. 23, 2635–2638 [2] Kumar, S. et al 1992. The Weighted Histogram Analysis Method for Free-Energy Calculations on Biomolecules. I. The Method. J. Comp. Chem. 13, 1011–1021
Methods
__init__
(bias_energies_full[, maxiter, ...])Weighted Histogram Analysis Method estimate
(trajs)param X: Simulation trajectories. ttrajs contain the indices of the thermodynamic state and expectation
(a)Equilibrium expectation value of a given observable. fit
(X)Estimates parameters - for compatibility with sklearn. get_model_params
([deep])Get parameters for this model. get_params
([deep])Get parameters for this estimator. log_likelihood
()meval
(f, *args, **kw)Evaluates the given function call for all models register_progress_callback
(call_back[, stage])Registers the progress reporter. set_model_params
([models, f_therm, pi, f, label])set_params
(**params)Set the parameters of this estimator. update_model_params
(**params)Update given model parameter if they are set to specific values Attributes
active_set
The active set of states on which all computations and estimations will be done. f
The free energies (in units of kT) on the configuration states. f_full_state
free_energies
The free energies (in units of kT) on the configuration states. free_energies_full_state
label
Human-readable description for the thermodynamic state of this model. logger
The logger for this class instance model
The model estimated by this Estimator model_active_set
msm_active_set
name
The name of this instance nstates
Number of active states on which all computations and estimations are done. nstates_full
Size of the full set of states. pi
The stationary distribution on the configuration states. pi_full_state
show_progress
whether to show the progress of heavy calculations on this object. stationary_distribution
The stationary distribution on the configuration states. stationary_distribution_full_state
unbiased_state
Index of the unbiased thermodynamic state. -
active_set
¶ The active set of states on which all computations and estimations will be done.
-
estimate
(trajs)¶ Parameters: X (tuple of (ttrajs, dtrajs)) – Simulation trajectories. ttrajs contain the indices of the thermodynamic state and dtrajs contains the indices of the configurational states.
- ttrajs : list of numpy.ndarray(X_i, dtype=int)
- Every elements is a trajectory (time series). ttrajs[i][t] is the index of the thermodynamic state visited in trajectory i at time step t.
- dtrajs : list of numpy.ndarray(X_i, dtype=int)
- dtrajs[i][t] is the index of the configurational state (Markov state) visited in trajectory i at time step t.
-
expectation
(a)¶ Equilibrium expectation value of a given observable.
Parameters: a ((M,) ndarray) – Observable vector Returns: val – Equilibrium expectation value of the given observable Return type: float Notes
The equilibrium expectation value of an observable a is defined as follows
\[\mathbb{E}_{\mu}[a] = \sum_i \mu_i a_i\]\(\mu=(\mu_i)\) is the stationary vector of the transition matrix \(T\).
-
f
¶ The free energies (in units of kT) on the configuration states.
-
fit
(X)¶ Estimates parameters - for compatibility with sklearn.
Parameters: X (object) – A reference to the data from which the model will be estimated Returns: estimator – The estimator (self) with estimated model. Return type: object
-
free_energies
¶ The free energies (in units of kT) on the configuration states.
-
get_model_params
(deep=True)¶ Get parameters for this model.
Parameters: deep (boolean, optional) – If True, will return the parameters for this estimator and contained subobjects that are estimators. Returns: params – Parameter names mapped to their values. Return type: mapping of string to any
-
get_params
(deep=True)¶ Get parameters for this estimator.
Parameters: deep (boolean, optional) – If True, will return the parameters for this estimator and contained subobjects that are estimators. Returns: params – Parameter names mapped to their values. Return type: mapping of string to any
-
label
¶ Human-readable description for the thermodynamic state of this model.
-
logger
¶ The logger for this class instance
-
meval
(f, *args, **kw)¶ Evaluates the given function call for all models Returns the results of the calls in a list
-
model
¶ The model estimated by this Estimator
-
name
¶ The name of this instance
-
nstates
¶ Number of active states on which all computations and estimations are done.
-
nstates_full
¶ Size of the full set of states.
-
pi
¶ The stationary distribution on the configuration states.
-
register_progress_callback
(call_back, stage=0)¶ Registers the progress reporter.
Parameters: - call_back (function) –
This function will be called with the following arguments:
- stage (int)
- instance of pyemma.utils.progressbar.ProgressBar
- optional *args and named keywords (**kw), for future changes
- stage (int, optional, default=0) – The stage you want the given call back function to be fired.
- call_back (function) –
-
set_params
(**params)¶ Set the parameters of this estimator. The method works on simple estimators as well as on nested objects (such as pipelines). The former have parameters of the form
<component>__<parameter>
so that it’s possible to update each component of a nested object. :returns: :rtype: self
-
show_progress
¶ whether to show the progress of heavy calculations on this object.
-
stationary_distribution
¶ The stationary distribution on the configuration states.
-
unbiased_state
¶ Index of the unbiased thermodynamic state.
-
update_model_params
(**params)¶ Update given model parameter if they are set to specific values
-