python-control · murrayrm · Jul 21, 2019 · Jul 7, 2019 · Jul 10, 2019
diff --git a/control/__init__.py b/control/__init__.py
@@ -84,3 +84,6 @@
 from numpy.testing import Tester
 test = Tester().test
 bench = Tester().bench
+
+# Initialize default parameter values
+reset_defaults()
diff --git a/control/config.py b/control/config.py
@@ -5,58 +5,133 @@
 # variables that control the behavior of the control package.
 # Eventually it will be possible to read and write configuration
 # files.  For now, you can just choose between MATLAB and FBS default
-# values.
+# values + tweak a few other things.
 
 import warnings
 
-# Bode plot defaults
-bode_dB = False                 # Bode plot magnitude units
-bode_deg = True                 # Bode Plot phase units
-bode_Hz = False                 # Bode plot frequency units
-bode_number_of_samples = None   # Bode plot number of samples
-bode_feature_periphery_decade = 1.0  # Bode plot feature periphery in decades
+__all__ = ['defaults', 'set_defaults', 'reset_defaults',
+           'use_matlab_defaults', 'use_fbs_defaults',
+           'use_numpy_matrix']
+
+# Package level default values
+_control_defaults = {
+    # No package level defaults (yet)
+}
+defaults = dict(_control_defaults)
+
+
+def set_defaults(module, **keywords):
+    """Set default values of parameters for a module.
+
+    The set_defaults() function can be used to modify multiple parameter
+    values for a module at the same time, using keyword arguments:
+
+        control.set_defaults('module', param1=val, param2=val)
+
+    """
+    if not isinstance(module, str):
+        raise ValueError("module must be a string")
+    for key, val in keywords.items():
+        defaults[module + '.' + key] = val
 
-# State space module variables
-_use_numpy_matrix = True        # Decide whether to use numpy.marix
 
 def reset_defaults():
-    """Reset package configuration values to their default values."""
-    global bode_dB; bode_dB = False
-    global bode_deg; bode_deg = True
-    global bode_Hz; bode_Hz = False
-    global bode_number_of_samples; bode_number_of_samples = None
-    global bode_feature_periphery_decade; bode_feature_periphery_decade = 1.0
-    global _use_numpy_matrix; _use_numpy_matrix = True
+    """Reset configuration values to their default (initial) values."""
+    # System level defaults
+    defaults.update(_control_defaults)
+
+    from .freqplot import _bode_defaults, _freqplot_defaults
+    defaults.update(_bode_defaults)
+    defaults.update(_freqplot_defaults)
+
+    from .nichols import _nichols_defaults
+    defaults.update(_nichols_defaults)
+
+    from .pzmap import _pzmap_defaults
+    defaults.update(_pzmap_defaults)
+
+    from .rlocus import _rlocus_defaults
+    defaults.update(_rlocus_defaults)
+
+    from .statesp import _statesp_defaults
+    defaults.update(_statesp_defaults)
+
+
+def _get_param(module, param, argval=None, defval=None, pop=False):
+    """Return the default value for a configuration option.
+
+    The _get_param() function is a utility function used to get the value of a
+    parameter for a module based on the default parameter settings and any
+    arguments passed to the function.  The precedence order for parameters is
+    the value passed to the function (as a keyword), the value from the
+    config.defaults dictionary, and the default value `defval`.
+
+    Parameters
+    ----------
+    module : str
+        Name of the module whose parameters are being requested.
+    param : str
+        Name of the parameter value to be determeind.
+    argval : object or dict
+        Value of the parameter as passed to the function.  This can either be
+        an object or a dictionary (i.e. the keyword list from the function
+        call).  Defaults to None.
+    defval : object
+        Default value of the parameter to use, if it is not located in the
+        `config.defaults` dictionary.  If a dictionary is provided, then
+        `module.param` is used to determine the default value.  Defaults to
+        None.
+    pop : bool
+        If True and if argval is a dict, then pop the remove the parameter
+        entry from the argval dict after retreiving it.  This allows the use
+        of a keyword argument list to be passed through to other functions
+        internal to the function being called.
+
+    """
+
+    # Make sure that we were passed sensible arguments
+    if not isinstance(module, str) or not isinstance(param, str):
+        raise ValueError("module and param must be strings")
+
+    # Construction the name of the key, for later use
+    key = module + '.' + param
+
+    # If we were passed a dict for the argval, get the param value from there
+    if isinstance(argval, dict):
+        argval = argval.pop(param, None) if pop else argval.get(param, None)
+
+    # If we were passed a dict for the defval, get the param value from there
+    if isinstance(defval, dict):
+        defval = defval.get(key, None)
+
+    # Return the parameter value to use (argval > defaults > defval)
+    return argval if argval is not None else defaults.get(key, defval)
 
 
 # Set defaults to match MATLAB
 def use_matlab_defaults():
-    """
-    Use MATLAB compatible configuration settings
+    """Use MATLAB compatible configuration settings.
 
     The following conventions are used:
-        * Bode plots plot gain in dB, phase in degrees, frequency in Hertz
+        * Bode plots plot gain in dB, phase in degrees, frequency in
+          Hertz, with grids
+        * State space class and functions use Numpy matrix objects
+
     """
-    # Bode plot defaults
-    global bode_dB; bode_dB = True
-    global bode_deg; bode_deg = True
-    global bode_Hz; bode_Hz = True
-    global _use_numpy_matrix; _use_numpy_matrix = True
+    set_defaults('bode', dB=True, deg=True, Hz=True, grid=True)
+    set_defaults('statesp', use_numpy_matrix=True)
 
 
 # Set defaults to match FBS (Astrom and Murray)
 def use_fbs_defaults():
-    """
-    Use `Feedback Systems <http://fbsbook.org>`_ (FBS) compatible settings
+    """Use `Feedback Systems <http://fbsbook.org>`_ (FBS) compatible settings.
 
     The following conventions are used:
         * Bode plots plot gain in powers of ten, phase in degrees,
-          frequency in Hertz
+          frequency in Hertz, no grid
+
     """
-    # Bode plot defaults
-    global bode_dB; bode_dB = False
-    global bode_deg; bode_deg = True
-    global bode_Hz; bode_Hz = False
+    set_defaults('bode', dB=False, deg=True, Hz=False, grid=False)
 
 
 # Decide whether to use numpy.matrix for state space operations
@@ -68,8 +143,8 @@ def use_numpy_matrix(flag=True, warn=True):
     flag : bool
         If flag is `True` (default), use the Numpy (soon to be deprecated)
         `matrix` class to represent matrices in the `~control.StateSpace`
-        class and functions.  If flat is `False`, then matrices are represnted
-        by a 2D `ndarray` object.
+        class and functions.  If flat is `False`, then matrices are
+        represented by a 2D `ndarray` object.
 
     warn : bool
         If flag is `True` (default), issue a warning when turning on the use
@@ -79,5 +154,5 @@ class and functions.  If flat is `False`, then matrices are represnted
     """
     if flag and warn:
         warnings.warn("Return type numpy.matrix is soon to be deprecated.",
-	              stacklevel=2)
-    global _use_numpy_matrix; _use_numpy_matrix = flag
+                      stacklevel=2)
+    set_defaults('statesp', use_numpy_matrix=flag)