Parameters

class decida.Parameters.Parameters(parent=None, specs=None, **kwargs)

Bases: decida.ItclObjectx.ItclObjectx

synopsis:

Parameter set manager class.

Parameters manages a set of instances of the Parameter class. Each Parameter instance has associated current value and ranges.

LevMar and Fitter use the Parameters instance to manage the optimization.

constructor arguments:

**kwargs (dict)

keyword=value specifications: configuration-options

configuration options:

verbose (bool, default=False)

If verbose is True, print more information if available.

gui (bool, default=True)

flag to indicate that a Parameters graphical user-interface should be displayed. Not currently implemented

example (from test_Parameters):

from decida.Parameters import Parameters
#-----------------------------------------------------------------
# specs:
# name, initial_value, include,
#     lower_limited, upper_limited, lower_limit, upper_limit
#-----------------------------------------------------------------
parobj = Parameters(specs=(
   ("L" , 150e-12, True, True, False, 0.0, 0.0),
   ("Co", 250e-15, True, True, False, 0.0, 0.0),
   ("Cu", 120e-15, True, True, False, 0.0, 0.0),
   ("C1",  25e-15, True, True, False, 0.0, 0.0),
   ("C2",  30e-15, True, True, False, 0.0, 0.0),
))
parobj.show("L")
parobj.modify("L", tied="1.0/(math.pow(2*math.pi*10e9,2)*Co)")
parobj.values([L,Co,Cu,C1,C2])
parobj.show("L")

public methods:

• public methods from ItclObjectx

• indexing:

  • <parameters_object>[“<parameter_name>”] returns the

    current value of the parameter named <parameter_name>

  • <parameters_object>[“<config_option>”] returns the

    value of the configuration option named <config_option>

  • <parameters_object>[“<parameter_name>”]=<value> sets the

    current value of the parameter named <parameter_name> to <value>

  • <parameters_object>[“<config_option>”]=<value> sets the

    value of the configuration option named <config_option> to <value>

• length:

  • len(<parameters_object>) returns the number of parameters in the parameter set.

• parameter-attributes :

  • each parameter instance has the following attributes, many which pertain only to Levenberg-Marquardt optimization:

    attribute:	default value:	description:
    initial_value	0.0	first value of parameter
    current_value	0.0	current value of parameter
    include	True	parameter is not fixed
    lower_limited	True	parameter has a lower-limit
    lower_limit	0.0	the lower-limit
    upper_limited	False	parameter has an upper-limit
    upper_limit	0.0	the upper-limit
    step	0.0	absolute step for derivatives
    relative_step	0.0	relative step for derivatives
    side	1	side to take derivatives: 1=forward, -1=reverse 2=two-sided
    minstep	0.0	minimum iteration step (not used)
    maxstep	0.0	maximum iteration step
    tied	“”	expression to tie parameter with other parameters
    print	True	print parameter value at each iteration

• parameter-conditions:

  • parameters can be checked for the following conditions:

  condition:	description:
  fixed	parameter is not allowed to vary
  included	parameter is allowed to vary (free or tied)
  tied	parameter is tied others by an expression
  untied	not tied
  free	parameter is allowed to vary
  limited	parameter is limited (upper or lower)
  step_limited	value of parameter change for one iteration is limited
  at_upper_limit	parameter current value is at upper-limit
  at_lower_limit	parameter current value is at lower-limit
  within_limits	parameter current value is within limits
  correct_limits	parameter upper_limit > lower_limit
  correct_step_limits	parameter maxstep > minstep

add(par, **kwargs)

add a parameter and specifications to the parameter set.

arguments:

par (str)

parameter name to add.

**kwargs (dict):

<attribute>=<value> specifications for the parameter

results:

• The parameter set is appended with par.
• The attributes of the parameter are set to specified values.

check(par, condition, verbose=False)

check a parameter condition.

arguments:

par (str)

parameter to check

condition (str)

parameter condition to check

verbose (bool, default=False)

enable or disable verbose mode.

results:

• if condition is True for parameter par, return True, else False.

check_any_free_limited()

check whether any free parameters are limited.

results:

• Check to see if any free parameters are limited.

check_any_free_step_limited()

check whether any free parameters are step limited.

results:

• Check to see if any free parameters are step limited.

check_correct_limits()

check whether parameter limits are consistent.

results:

• Check to see if all parameters have attributes lower_limit < upper_limit.

check_correct_step_limits()

check whether parameter step limits are consistent.

results:

• Check to see if all parameters have attributes minstep < maxstep.

check_within_limits()

check whether parameter current value is within limits.

results:

• Check to see if all parameters have current value within the range lower_limit, upper_limit, if the parameter is limited.

free_indices()

return list of parameter indices for paramteres that

are free to vary.

results:

• Returns a list of indices (within the parameter set) of parameters that have the attribute “free”.

free_pars()

return list of parameters that are free to vary.

results:

• Returns a list of parameters that have the attribute “free”.

free_values(values=None)

set or return free parameter values.

arguments:

values (list or tuple, default=None)

list of values to set free parameters current value attribute. if values is not specified, return a list of free parameter current values.

results:

• Every free parameter current value is set to a value in the value list, if values is specified.
• If values is not specified, return the list of free parameter current values.

list_of_attr(condition)

return bool list of checked condition for each parameter.

arguments:

condition (str)

condition string for checking parameter set.

results:

• Returns list of boolean values for whether or not the condition is met by each parameter.

list_of_pars(condition)

return list of parameters with condition.

arguments:

condition (str)

condition string for filtering parameter set.

results:

• parameter list is returned with pars with condition True.

modify(par, **kwargs)

modify a parameter’s attributes

arguments:

par (str)

parameter name to modify.

**kwargs (dict)

<attribute>=<value> specifications for the parameter

results:

• The attributes of the parameter are modified.

pars()

return parameter names.

results:

• list of parameter names in the parameter set is returned.

reset()

reset all parameters to initial values

results:

• parameters are reset to initial values.

show(par=None)

show parameters and attributes.

arguments:

par (str, default=None)

parameter name to show. If not specified, all parameters are shown.

results:

• parameter name and attributes of the specified parameter, or all parameters if par is not specified, are displayed.

values(values=None)

set or return parameter values.

arguments:

values (list or tuple, default=None)

list of values to set parameters current value attribute. if values is not specified, return a list of parameter current values.

results:

• Every parameter current value is set to a value in the value list, if values is specified.
• If values is not specified, return the list of parameter current values.