/cloaked-octo-computing-machine

Experimental_Python

Primary LanguagePython

cloaked-octo-computing-machine

Experimental_Python

Linear Regression

Example of how to make linear regression in python using scipy

Pickle

Stores python objects in files. Useful to save processed data or training coefs for CNNs.

Note: Files generated with pickle for python 3 are not backward compatible for python 2.7

Sample Generator Useful to generate more samples to train CNNs.

How to solve the error in anaconda

This application failed to start because it could not find or load the Qt platform plugin "xcb" in "".

Reinstalling the application may fix this problem. Abortado ('core' generado)

As the message says we need to reinstall the program, the issue here is which program we need to reinstall. This are the commands we need to run in order to fix this bug:

sudo /opt/anaconda3/bin/conda remove qt
sudo /opt/anaconda3/bin/conda remove pyqt
sudo /opt/anaconda3/bin/conda install qt
sudo /opt/anaconda3/bin/conda install pyqt

Notes

ternary operator:

t="10" if 4 < 5 else "22"

Dict max or min or any lambda:

d = {'a':1, 'b':22, 'c':10}
print("Max val: {}".format(d[max(d, key=d.get)]))

Debug

When there are several python versions in the same PC to specify which pdb should be used try:

python3 -m pdb <script_name>.py
# for python 2
python -m pdb <script_name>.py

References in python

mutt

http://effbot.org/zone/call-by-object.htm
http://effbot.org/zone/python-objects.htm

Here is an example on how python hides memory:

def dict_modifier(d, key):
d.pop(key, None)

sample_dict = {'some_key': 'some value'}
dict_modifier(sample_dict, 'some_key')
print(sample_dict)  # {}

The function dict_modifier removes a value form the dictionary passed to it, it handles the dictionary as a reference. But python not always takes the arguments as references for example:

def adder(n):
n += 1

i = 1
adder(i)
print(i)  # 1

The primitives are not passed as references, but rather as copies.

Compile a python script for correctness

python -m py_compile xpad_diag_helper.py

Get import paths

https://stackoverflow.com/questions/5751292/how-to-get-current-import-paths-in-python

The path locations that python cheks by default can be inspected in sys.path.

import sys
print sys.path

Class (static) variables in python

A static variable is a variable which is shared among all the instances of the class, if its value changes, changes for all the instances. Also does NOT need an instance of the class to exists.
For example:

class A:
static_variable = "I exist"
def __init__(self):
self.non_static_var = "I need an instance to exist"
print(A.static_variable)
print(A.non_static_var)

Every object can access the static variable

class B:
shared_var = "I'm shared"
def __init__(self):
self.instance_only_var = "Im only for my object"

ib_1 = B()
ib_2 = B()
print(B.shared_var)

print(ib_2.shared_var)
print(ib_1.shared_var)
ib_2.shared_var = "catorce"

print(ib_2.shared_var)
print(ib_1.shared_var)
####
print(ib_2.instance_only_var)
print(ib_1.instance_only_var)
ib_2.instance_only_var = "only for ib2"
print(ib_2.instance_only_var)
print(ib_1.instance_only_var)


Get the value in little endian of an instruction:


'/bin/sh'[::-1].encode().hex()
'68732f6e69622f'


Installed python not found


When installing with pip --user the executable files go to the
path specified by:


python3 -m site --user-base


On windows the scripts go to %USERPROFILE%\AppData\Roaming\Python\Scripts


Get headers for C/C++ libraries


python3 -c "from __future__ import print_function; from distutils import sysconfig; print(sysconfig.get_python_inc())"



Why python sucks