.. _My target:

Python
======


.. toctree::
    :maxdepth: 2

    packaging.rst
    text.rst
    lang.rst
    asyncio.md


Misc Topics
-----------

Data Filtering
**************

taking a generator, using lambda and then unpack the result into a list

.. code-block:: python

    # only numbers divisible by 13
    print([*filter(lambda x: not x % 13, range(100))])

JS style map()
**************

return an iterator of the return value of the lambda applied to each item in the given iterable generator


.. code-block:: python

    data = [*map(lambda x: (c := x**2, format(c, "04X")), range(100))]
    for item in data: print(item)

Data Representation
-------------------


* Integer
    * Decimal
    * Hexa
    * Octal
    * binary
* Float
    * Decimal
    * Scientific
* Complex
* bytes
* utf-8 and utf-16


.. code-block:: python

    n = 10   # decimal literal
    n = 0x10 # hexadecimal literal, decimal value 16
    n = 0o10 # Octal literal, decimal value 8
    n = 0b10 # binary literal,decimal value 3

    n, t, s = 3.14, .1, 4. # float literals
    c = 2.99e8 # speed of light in scientific notation

    k = 3 + 4j # complex numbers
    n = 2j # imaginary number



Pydantic and Datamodels
-----------------------

When parsing a dict, configure whether pydantic ignore and forebids extra fields


.. code-block:: python

    from typing import Optional
    from pydantic import BaseModel, Extra
    class Query(BaseModel):
        id: str
        name: Optional[str]
        class Config:
            extra = Extra.forbid
    
    # this will fail
    Query.parse_object({'name':'', id: 12345, 'type': 'generic'})