Strange things
--------------


2000 vintages at once
=====================
This is an undocumented feature.
(AL)FRED is limited to a maximum of 2000 vintage dates.
Unfortunately, their implementation does not allow for client-side pagination - see `issues/2 <https://github.com/TomasKoutek/pystlouisfed/issues/2>`_ and `fredapi/pull/52 <https://github.com/mortada/fredapi/pull/52>`_).

FRED Maps units
===============

:py:class:`pystlouisfed.FREDMaps.regional_data` has a units parameter.
In the official documentation is only "The units of the series you want to pull.".
But it doesn't matter what we set here, only the title will change:

.. code-block:: text

    https://api.stlouisfed.org/geofred/regional/data?series_group=882&date=2013-01-01&region_type=state&units=ABC&frequency=a&season=NSA

.. code-block:: xml

    <series_data title="2022 Per Capita Personal Income by State (ABC)" region="state" seasonality="Not Seasonally Adjusted" units="ABC" frequency="Annual">
        <observation date="2013-01-01" region="Arizona" code="04" value="36877" series_id="AZPCPI"/>
        <observation date="2013-01-01" region="Hawaii" code="15" value="43553" series_id="HIPCPI"/>
        ...

.. code-block:: text

    https://api.stlouisfed.org/geofred/regional/data?series_group=882&date=2013-01-01&region_type=state&units=SOME-UNIT-PARAMETER&frequency=a&season=NSA

.. code-block:: xml

    <series_data title="2022 Per Capita Personal Income by State (SOME-UNIT-PARAMETER)" region="state" seasonality="Not Seasonally Adjusted" units="SOME-UNIT-PARAMETER" frequency="Annual">
        <observation date="2013-01-01" region="Arizona" code="04" value="36877" series_id="AZPCPI"/>
        <observation date="2013-01-01" region="Hawaii" code="15" value="43553" series_id="HIPCPI"/>
        ...

Time Zones
==========

FRED/ALFRED works with date in 99% of cases.
But what is a date? For example, the friday "2022-02-04" can be almost anything - it depends on the time zone:

.. image:: timezones.png

Let's say we are in the "Europe/Prague" timezone (UTC+1) and at 2:00am we call the method :py:meth:`pystlouisfed.FRED.series_observations`:

.. code-block:: python

    from pystlouisfed import FRED
    from datetime import date

    fred = FRED(api_key='abcdefghijklmnopqrstuvwxyz123456')
    fred.series_observations(series_id='GDP', realtime_start=date.today(), realtime_end=date.today())


FRED/ALFRED will return the error:

.. warning::
    "Bad Request. Variable realtime_start can not be after today's date..."

because it works in the **timezone "US/Central"** (UTC−06:00)!
Probably all the date values that the API returns are in "US/Central", but I haven't verified it.