Tutorial by Examples: an

The Canny algorithm is a more recent edge detector designed as a signal processing problem. In OpenCV, it outputs a binary image marking the detected edges. Python: import cv2 import sys # Load the image file image = cv2.imread('image.png') # Check if image was loaded improperly and exit i...

import cv2 import numpy as np img = cv2.imread('<your_image>') gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) cv2.imshow('image', img) cv2.imshow('gray', gray) cv2.waitKey(0) cv2.destroyAllWindows()

django-filter is generic system for filtering Django QuerySets based on user selections. The documentation uses it in a function-based view as a product model: from django.db import models class Product(models.Model): name = models.CharField(max_length=255) price = models.DecimalField(...

The following procedure is a generic one which will be used to log all errors in an application to a common error log table. CREATE OR REPLACE PROCEDURE log_errors ( p_calling_program IN VARCHAR2, p_error_code IN INTEGER, p_error_description IN VARCHAR2 ) IS PRAGMA AUTONOMOUS_TRANSAC...

Atomic types are the building blocks of lock-free data structures and other concurrent types. A memory ordering, representing the strength of the memory barrier, should be specified when accessing/modifying an atomic type. Rust provides 5 memory ordering primitives: Relaxed (the weakest), Acquire (f...

Use the analytical function row_number(): with t as ( select col1 , col2 , row_number() over (order by col1, col2) rn from table ) select col1 , col2 from t where rn between N and M; -- N and M are both inclusive Oracle 12c handles this more easily with OFFSET and FETCH.

To open a new WebSocket, simply add something like: var WebSocket = require("ws"); var ws = new WebSocket("ws://host:8080/OptionalPathName); // Continue on with your code... Or to open a server, use: var WebSocketServer = require("ws").Server; var ws = new WebSocketS...

Basic docs can be found here app.get('/path/:id(\\d+)', function (req, res, next) { // please note: "next" is passed if (req.params.id == 0) // validate param return next(new Error('Id is 0')); // go to first Error handler, see below // Catch error on sync operation ...

app.use() and middleware can be used for "before" and a combination of the close and finish events can be used for "after". app.use(function (req, res, next) { function afterResponse() { res.removeListener('finish', afterResponse); res.removeListener('clos...

When required you can tell Docker to execute additional commands on an already running container using the exec command. You need the container's ID which you can get with docker ps. docker exec 294fbc4c24b3 echo "Hello World" You can attach an interactive shell if you use the -it option...

You can create a new cron entry by simply typing crontab -e on the command line. If it's the first time you want to edit your crontab(le), you will be prompted with an editor selection: no crontab for <user> - using an empty one Select an editor. To change later, run 'select-editor'. ...

We have a set of data We would like to see by using the following expression in the detail textbox. we can achieve the Remark =IIF(Fields!Points.Value>=10,"Good","Average")

Using the Swift class Mirror works if you want to extract name, value and type (Swift 3: type(of: value), Swift 2: value.dynamicType) of properties for an instance of a certain class. If you class inherits from NSObject, you can use the method class_copyPropertyList together with property_getAttrib...

using NUnit.Framework; namespace MyModuleTests { [TestFixture] public class MyClassTests { [TestCase(1, "Hello", true)] [TestCase(2, "bye", false)] public void MyMethod_WhenCalledWithParameters_ReturnsExpected(int param1, string para...

(Access Code)[https://github.com/vDoers/vDoersCameraAccess]

Process manager is generally used in production to deploy a nodejs app. The main functions of a process manager are restarting the server if it crashes, checking resource consumption, improving runtime performance, monitoring etc. Some of the popular process managers made by the node community are ...

Prerequisites git clang and clang++ 3.4^ or gcc and g++ 4.8^ Python 2.6 or 2.7 GNU Make 3.81^ Get source Node.js v6.x LTS git clone -b v6.x https://github.com/nodejs/node.git Node.js v7.x git clone -b v7.x https://github.com/nodejs/node.git Build cd node ./configure make -jX su...

Analog pins can be used to read voltages which is useful for battery monitoring or interfacing with analog devices. By default the AREF pin will be the same as the operating voltage of the arduino, but can be set to other values externally. If the voltage to read is larger than the input voltage, a ...

Being able to understand Error/Exit codes is a fundamental skill for developers on Window's machine. Yet for many, the cryptic hexadecimal code that can be produced on an application exiting with on error can prove to be time consuming and painstaking process for the developer to track down and isol...

Anchor tag helper is used generate href attributes to link to a particular controller action or MVC route. Basic example <a asp-controller="Products" asp-action="Index">Login</a> Sometimes, we need to specify additional parameters for the controller action that ...