Python

Version Check

Tensorflow Version

import tensorflow as tf
 tf.__version__
  

gstreamer version

dpkg -l | grep gstreamer

Python3 Setting

Install pip3

$ sudo apt-get install python3 python3-pip python3-dev python3-setuptools
  

$ sudo pip3 install --upgrade pip
  

Install pip3 In Mac

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
python3 get-pip.py
pip3 --version
  

Install virtualenv (if need)

Install

$ pip3 install virtualenv
  

Create a virtual environment

$ virtualenv venv

Activate virtual environment

$ source venv/bin/activate
  

Deactivate

$ deactivate

virtualenvwrapper

install

$ pip3 install virtualenvwrapper
  

Create a virtual environment

$ mkvirtualenv venv

Work on a virtual environment

$ workon venv

Save pip3 package list to .txt file

$ pip3 freeze > requirements.txt
  

Remove virtualenv

$ sudo apt-get remove --auto-remove virtualenv
  

$ sudo apt-get remove virtualenv
  

Install jupter notebook

Step 1: Install Package

$ sudo apt update && sudo apt -y upgrade
$ sudo apt install python3-pip python3-dev
$ sudo -H pip3 install --upgrade pip
$ sudo -H pip3 install virtualenv
  

Step 2: create vitual env

$ virtualenv jupyterenv
$ source jupyterenv/bin/activate
$ pip install jupyter
  

Step 3: Run notebook

$ jupyter notebook --port 9999
  

$ jupyter execute notebook.ipynb

Example of Inheritance

Before using inheritance

class Panda:
	def __init__(self, name, age):
		self.name = name
		self.age = age
	def speak(self):
		print("bamboo")

class Rabbit:
	def __init__(self, name, age):
		self.name = name
		self.age = age
	def speak(self):
		print("carrot")
  

After using inheritance

class Animal:
	def __init__(self, name, age):
		self.name = name
		self.age = age
	def show(self):
		print(f"I'm {self.name}. I am {self.age}")	
		
class Panda(Animal): # inheriting upper level class
	def __init__(self, name, age, color):
		super().__init__(name, age)
		self.color = color

	def speak(self):
		print("bamboo")

class Rabbit(Animal): # inheriting upper level class
	def speak(self):
		print("carrot")

temp1 = Panda("lingling", 10, "blackwhite")
temp1.show()

temp2 = Rabbit("Tom", 5)
temp2.show()
  

Edit Specific Line

Original test.txt

aaa
bbb
ccc
  

Run this piece:

ss = open("test.txt", "r")
list_of_lines = ss.readlines()
list_of_lines[1] = "kkk\n"

ss = open("test.txt", "w")
ss.writelines(list_of_lines)
ss.close()
  

Modified test.txt

aaa
kkk
ccc
  

Array and List

Convert Array/List

import numpy as np
from numpy import array

custom_roi_points = array([(50,60),(50,100),(100,50),(100,100)])

# array to list
custom_roi_list = custom_roi_points.tolist()

# list to array
custom_roi_arr = array(custom_roi_list)

List

Create

List = []

List = [1, 2, 3]

List = [[10,10], [20,20]]

Size of list

len(List)

Add element

Use append(), you can add one elements in the end of the list :
```
List.append(x)
```
Use insert, you can add element in specific position:
```
List.insert(index, data)
```
```
List.insert(1, 5)
```
Use extend, you can add multiple elements in the end of the list:
```
List.extent([x, y , z])
```
```
List.extent([3, 4 , 5])
```
clear()
```
list.clear()
```

Access Element

Access last element:

List[-1]

deeo copy list

import copy
a = [1, 2, 3]
b = copy.deepcopy(a)
  

ls Directory using glob

sorting by create time

sorted_files = sorted(glob.glob('*'), key=os.path.getctime) 
for i in sorted_files:
	pass
  

sorting by touched time

sorted_files = sorted(glob.glob('*'), key=os.path.getatime) 
for i in sorted_files:
	pass
  

sorting by modified time

sorted_files = sorted(glob.glob('*'), key=os.path.getmtime) 
for i in sorted_files:
	pass
  

sorting by size

sorted_files = sorted(glob.glob('*'), key=os.path.getsize) 
for i in sorted_files:
	pass
  