[utils] add a function to get parameters from either configuration file or command-line

bob/rppg/base/utils.py

@@ -99,3 +99,46 @@ def build_bandpass_filter(fs, order, plot=False):
     pyplot.show()
 
   return b
+
+
+def get_parameter(args, configuration, keyword, default):
+  """ Get the right value for a parameter
+
+  The parameters are either defined in a separate configuration file
+  or given directly via command-line. Note that the command-line
+  has priority over the configuration file.
+
+  As a convention, parameters made with more than one word 
+  are provided with an underscore in the configuration file, and with an
+  hyphen in the command-line:
+
+    - configuration:  batch_size=64
+    - command line:   --batch-size=64
+
+  Parameters
+  ----------
+  args: dictionary
+    The arguments as parsed from the command line.
+  configuration: object
+    The arguments given by the configuration file.
+  keyword: string
+    the keyword for the parameter to process (in the "configuration" style)
+  default: 
+    The default value of the parameter
+
+  Returns
+  -------
+  arg:
+    The right value for the given keyword argument
+
+  """
+ 
+  args_kw = '--' + keyword.replace('_', '-')
+  _type = type(default)
+  arg = _type(args[args_kw])
+  if hasattr(configuration, keyword):
+    arg = getattr(configuration, keyword)
+  if _type(args[args_kw]) is not default:
+    arg = _type(args[args_kw])
+  return arg
+