Measures
========

A device measures the atmospheric pressure of an exterior zone.  When
meteorological conditions aren't good, measures aren't reliable, and
the device has a sensor that checks whether the meteorological
conditions are good or bad. We have been given a non empty
:class:`list` of measures, corresponding to a determined time
period. This list contains real values (:class:`float`) corresponding
to atmospheric pressures, taken in chronological order. This list also
contains the characters asterisk (``'*'``) and equals (``'='``). When
traversing the list if an asterisk is found, it means that the
following measures aren't reliable and if an equal sign is found, it
means that the following measures are reliable. The initial values of
the given list are reliable.

Save the following functions into the same file :file:`measures.py`.

#. Write the function :py:func:`separate`, that takes a list of
   measures as described, and returns a :class:`tuple` with two
   lists. The first list should only have the reliable measures of the
   given list and the second list should only have the measures of the
   given list that aren't reliable. For example:

   .. literalinclude:: test-measures-1.txt
      :language: python3
      :lines: 3-5

   More tests are provided in file :download:`test-measures-1.txt
   <test-measures-1.txt>`.

#. Write the function :py:func:`average`, that takes a list of real
   values, and returns the average (:class:`float`) of the list
   elements. Suppose that the list is not empty. Example:

   .. literalinclude:: test-measures-2.txt
      :language: python3
      :lines: 3-10

   More tests are provided in file :download:`test-measures-2.txt
   <test-measures-2.txt>`.

	    
#. Write the function :py:func:`averages`, that takes a list of
   measures as described, and returns a :class:`tuple` with two
   averages (:class:`float`) corresponding respectively to the average
   of the reliable measures and the average of all measures. For
   example:

   .. literalinclude:: test-measures-3.txt
      :language: python3
      :lines: 3-8

   This function :py:func:`averages` must call the previous two
   functions :py:func:`separate` and :py:func:`average`.

   More tests are provided in file :download:`test-measures-3.txt
   <test-measures-3.txt>`.

#. Write the function :py:func:`proportion`, that takes a list of
   measures as described, and returns the percentage (:class:`float`)
   of reliable measures with respect to the total number of measures
   in the given list. For example:

   .. literalinclude:: test-measures-4.txt
      :language: python3
      :lines: 3-6

   This function :py:func:`proportion` must call the previous function
   :py:func:`separate`.


   More tests are provided in file :download:`test-measures-4.txt
   <test-measures-4.txt>`.

.. rubric:: Solution

A solution of these functions is provided in file :download:`measures.py <solutions/measures.py>`