====== Python ======

 "Eventually I got better -- I started making my own mistakes."


Fun reason to learn Python:- \\
[[https://www.4dbrix.com/documentation/python/]]


Python Game:- \\
https://www.twilio.com/quest



Rather more serious tutorial:- \\
[[https://docs.python.org/3/tutorial/]]


[[python:flask|Flask application framework]] \\


===== Install pip3 =====


<code python>
# apt-cache search python3-pip
python3-pip - Python package installer
root@sysmgmt:~# apt-get install python3-pip
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
  binutils binutils-common binutils-x86-64-linux-gnu b
...edited...
</code>



===== Data Structures =====

[[python:python-data-struct|Python Data Structures]]


===== Python Code =====

[[python:python-code|Python code snippets]]

===== Print Formatting =====

<code python>
>>> print ("this is a {LENGTH} {STRING} print").format(LENGTH='short', STRING='test')
this is a short test print
>>> 

print("Creating '{}' role in account '{}'".format(role_name, event["account_id"]))
</code>


===== Date Time =====

<code python>
from datetime import datetime

print("now", datetime.now().replace(microsecond=0))

now 2023-09-12 12:44:22
</code>


With format string:-

<code python>
from datetime import datetime

raw_time = datetime.now().replace(microsecond=0)
now = raw_time.strftime("%d/%m/%Y %H:%M:%S")
</code>
Gives:- "04/10/2023 16:37:43"



===== Virtual Environment =====

<code python>
python3 -m venv <venv name>

eg.
$ python3 -m venv stuff-env


# EACH time you will need to run this to avtivate the virtual env:-

$ source stuff-env/bin/activate
(stuff-env) $ 
</code>

''pip freeze'' shows current modules, so echo this to ''requirements.txt'' to automatically load modules 

  pip freeze > requirements.txt


To quit the venv, use ''deactivate'' command (which venv adds to your path)

<code>
$ deactivate
$
</code>



===== requirements.txt file =====

Specific versions of packages can be installed from a ''requirements.txt'' file, this avoids pip installing a module in a venv which is a later release than the code was written for:-

<code>
$ cat requirements.txt
Jinja2==2.11.2
PyYAML==3.13
SQLAlchemy==1.3.16
</code>


<code python>
$ pip install -r requirements.txt
</code>

===== Comments =====


[[https://realpython.com/python-comments-guide/]]\\


===== json.dumps =====

<code python>
print(json.dumps(clusterinfo))
</code>
produced the following error because of 'LastModified': datetime.datetime(2021, 8, 10, 12, 59, 25, tzinfo=tzutc()):-

TypeError: Object of type datetime is not JSON serializable


Serialization is the process of converting the state of an object, that is, the values of its properties, into a form that can be stored or transmitted.


Solution is to apply a default convert to str for anything unknown. But this will create an issue getting date.time string back to a date,time type obect.
<code python>
print(json.dumps(clusterinfo, indent=4, sort_keys=True, default=str))
</code>