Tempscat Files
==============


Let's imagine an institution called *Tempscat* intended to collect data about whether conditions all around Catalonia.
*Tempscat* composed of a central station (aka *TCentral*) connected to a network of *Tempscat Municipal Stations* (aka *TMuni*) located in many towns in Catalonia that send information about the whether variables in that spot.


Let's focus on the temperature variable.
Each *TMuni* is constantly measuring the temperature and computes the average temperature for every hour.
This information is sent in lots of several hours to the *TCentral*.
Therefore *TCentral* receives a number of messages from each *TMuni* throughout the day, collects them all and produces a daily file with all the measures received that day.
This is a `csv` file (Comma Separated Values) whose format is as follows: each line has the town name followed by several float numbers all separated by ``','``.
Each town usually appears in several lines since the *TCentral* in that town send severals lots throughout the day.

For example the file :download:`temp_11-1-2026.csv <temp_11-1-2026.csv>` contains information about the temperature from three towns collected in lots of 6 hours:

    .. literalinclude:: temp_11-1-2026.csv
        :language: python

Since the communication system is not perfect, some temperature values might be corrupted and include characters that cannot be interpreted as a numeric value.
For instance, notice in the above example that line 7 contains and character ``'E'``,
ine 11 contains the character ``'o'``
and line 12 contains the caracter ``'A'``. Anything that cannot be interpreted as numeric value (either float or integer) should be **disregarded**.

Given a file like this, we wish to compile its information to produce a file with the daily minimum and maximum temperatures for each town. This ought to be a CSV file with the following format:

    #. the town name (:class:`str`)
    #. the minimum temperature (:class:`float`)
    #. the maximum temperature (:class:`float`)
    #. the number of valid temperature measures (:class:`int`)
    #. the valid temperature measures (sequence of :class:`float`)

For example, the output expected from the above file would be the file :download:`tempminmax_11-1-2026.csv <tempminmax_11-1-2026.csv>`:

    .. literalinclude:: tempminmax_11-1-2026.csv
        :language: python

Notice that ``Barcelona`` has 24 valid measures whereas ``La Cellera de Ter`` has 23 and ``Sort`` has only 22, due to the invalid characters found in the input file.

To this purpose you are asked to deliver the following Python function in the module :mod:`tempscat` (file :file:`tempscat.py`):

    .. py:function:: temp_join(in_filename, out_filename)

such that

    **given**

        - `in_filename`, a :class:`str` with the filename of a file with the temperatures of one day as described above
        - `out_filename`,  a :class:`str`  with the name of the output file as described above

    **returns** an :class:`int` with the number of municipalites processed

    **produces** a file named `out_filename` with the format and compiled info from the info `in_filename` as  described above.

.. note:: The implement this function here you have a code snippet and a recommendation:

    - To chech whether a value read from the file is a valid numeric value you can used the file :download:`is_float.py <is_float.py>`. You can download it and either import or copy into your code file.
    - It is recommended to store the temperatures for each town coming from several lines of `in_filename` into a **dictionary** where the key is the town name and the value is the list of processed, numeric temperatures for that town name.

Doctests are available in the file :download:`temp_join.test`.
The file to pass these doctests are available at:

    - :download:`temp_11-1-2026.csv <temp_11-1-2026.csv>`
    - :download:`temp_bcn_11-1-2026.csv <temp_bcn_11-1-2026.csv>`
    - :download:`temp_12-1-2026.csv <temp_12-1-2026.csv>`
    - :download:`temp_13-1-2026.csv <temp_13-1-2026.csv>`
    - :download:`temp_14-1-2026.csv <temp_14-1-2026.csv>`