Pupli – Page 101

Resize image in OpenCV Python

March 4, 2019

import cv2
import numpy as np

image = cv2.imread("cow.jpg")
print(image.shape)  # (559, 838, 3)

old_width = image.shape[1]  # 838
old_height = image.shape[0]  # 559

# resize by custom size
new_width = 600
new_height = 400
resized = cv2.resize(image, (new_width, new_height))
cv2.imshow("image", resized)

# resize by ratio
width_ratio = 0.5
height_ration = 0.5
resized2 = cv2.resize(image, (0, 0), image, width_ratio, height_ration)
cv2.imshow("image2", resized2)

cv2.waitKey(0)
cv2.destroyAllWindows()

References
https://github.com/mhdr/OpenCVSamples/tree/master/008

Gray Scale image with OpenCV Python

March 4, 2019

import cv2
import numpy as np

image_gray = cv2.imread("cow.jpg", cv2.IMREAD_GRAYSCALE)
cv2.imshow("image3", image_gray)

# or just convert from original image
image = cv2.imread("cow.jpg")
image_gray2 = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
cv2.imshow("image4", image_gray2)

cv2.waitKey(0)
cv2.destroyAllWindows()

References
https://github.com/mhdr/OpenCVSamples/tree/master/007

Convert BGR Color to RGB with OpenCV Python

March 4, 2019

import cv2
import numpy as np

image = cv2.imread("cow.jpg")
cv2.imshow("image", image)

fixed = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
cv2.imshow("image2", fixed)

cv2.waitKey(0)
cv2.destroyAllWindows()

References
https://github.com/mhdr/OpenCVSamples/tree/master/007

Deploy Python applications into stand-alone executables

March 4, 2019

pip install pyinstaller

pyinstaller --name CaptainTsubasa run.py

References
https://www.pyinstaller.org/
https://pyinstaller.readthedocs.io/en/stable/

python-telegram-bot

February 20, 2019

References

https://github.com/python-telegram-bot/python-telegram-bot/wiki/Code-snippets

/bin/sh^M : bad interpreter

February 19, 2019

dos2unix run.sh

References
https://stackoverflow.com/questions/2920416/configure-bin-shm-bad-interpreter

Terminating a Python script

February 19, 2019

import sys
sys.exit()

os._exit(errorcode)

References
https://stackoverflow.com/questions/73663/terminating-a-python-script

Detect Ctrl+C in Python

February 6, 2019

#!/usr/bin/env python
import signal
import sys
def signal_handler(sig, frame):
        print('You pressed Ctrl+C!')
        sys.exit(0)
signal.signal(signal.SIGINT, signal_handler)
print('Press Ctrl+C')
signal.pause()

References
https://stackoverflow.com/questions/1112343/how-do-i-capture-sigint-in-python

Preventing Windows OS from sleeping while your python code runs

February 6, 2019

class WindowsInhibitor:
    '''Prevent OS sleep/hibernate in windows; code from:
    https://github.com/h3llrais3r/Deluge-PreventSuspendPlus/blob/master/preventsuspendplus/core.py
    API documentation:
    https://msdn.microsoft.com/en-us/library/windows/desktop/aa373208(v=vs.85).aspx'''
    ES_CONTINUOUS = 0x80000000
    ES_SYSTEM_REQUIRED = 0x00000001

    def __init__(self):
        pass

    def inhibit(self):
        import ctypes
        print("Preventing Windows from going to sleep")
        ctypes.windll.kernel32.SetThreadExecutionState(
            WindowsInhibitor.ES_CONTINUOUS | \
            WindowsInhibitor.ES_SYSTEM_REQUIRED)

    def uninhibit(self):
        import ctypes
        print("Allowing Windows to go to sleep")
        ctypes.windll.kernel32.SetThreadExecutionState(
            WindowsInhibitor.ES_CONTINUOUS)

import os

osSleep = None
# in Windows, prevent the OS from sleeping while we run
if os.name == 'nt':
    osSleep = WindowsInhibitor()
    osSleep.inhibit()

# do slow stuff

if osSleep:
    osSleep.uninhibit()

References
https://trialstravails.blogspot.com/2017/03/preventing-windows-os-from-sleeping.html

Create an Enum in Python

February 3, 2019

from enum import Enum
class Color(Enum):
     RED = 1
     GREEN = 2
     BLUE = 3

References
https://docs.python.org/3/library/enum.html