channels

What are the major conda channels, and what are their focuses? I can't seem to find any documentation on what major channels are available and when to choose one over the other. What is the relationship to the "default" channel? How does one decide what order to put them in? In general, I use anaconda conda_forge r bioconda defaults But I've been running into some problems with my environment breaking. abc anaconda conda-forge r bioconda These are all channels from which packages can be installed. They are not anymore special than the default channel. You can even create your own channel on

The go tour has this example for channels: https://tour.golang.org/concurrency/2 package main import "fmt" func sum(a []int, c chan int) { sum := 0 for _, v := range a { sum += v } c <- sum // send sum to c } func main() { a := []int{7, 2, 8, -9, 4, 0} c := make(chan int) go sum(a[:len(a)/2], c) go sum(a[len(a)/2:], c) x, y := <-c, <-c // receive from c fmt.Println(x, y, x+y) } The channel c is modified in the sum function and the changes persist after the function has terminated. Obviously c was passed by reference but no pointer to c was created. Are channels implicitly passed by reference

Java NIO offers SocketChannel and ServerSocketChannel which can be set to non-blocking mode (asynchronous). Most of the operations return a value that corresponds to success or that the operation is not yet done. What is the purpose of AynchronousSocketChannel and AsynchronousServerSocketChannel then, apart from the callback functionalities? which can be set to non-blocking mode (asynchronous) There's your misapprehension, right there. Non-blocking mode is different from asynchronous mode. A non-blocking operation either transfers data or it doesn't. In either case there is no blocking, and

I am new to Golang. Right now I am trying to figure out how to make an any-to-one channel in Golang, where the setup is as follows: say I have two goroutines numgen1 and numgen2 executing concurrently and writing numbers to channels num1 resp. num2. I would like to add the numbers sent from numgen1 and numgen2 in a new process, addnum. I have tried something like this: func addnum(num1, num2, sum chan int) { done := make(chan bool) go func() { n1 := <- num1 done <- true }() n2 := <- num2 <- done sum <- n1 + n2 } but this seems sadly incorrect. Could someone please give me some ideas? Thank you

The answers at Can I determine the number of channels in cv::Mat Opencv answer this question for OpenCV 1: you use the Mat.channels() method of the image. But in cv2 (I'm using 2.4.6), the image data structure I have doesn't have a channels() method. I'm using Python 2.7. Code snippet: cam = cv2.VideoCapture(source) ret, img = cam.read() # Here's where I would like to find the number of channels in img. Interactive attempt: >>> img.channels() Traceback (most recent call last): File "<interactive input>", line 1, in <module> AttributeError: 'numpy.ndarray' object has no attribute 'channels' >>>

I am using goroutines/channels to check if list of urls are reachable. Here is my code. This seems to always return true. Why is the timeout case not getting executed? The goal is to return false even if one of the urls is not reachable import "fmt" import "time" func check(u string) bool { time.Sleep(4 * time.Second) return true } func IsReachable(urls []string) bool { ch := make(chan bool, 1) for _, url := range urls { go func(u string) { select { case ch <- check(u): case <-time.After(time.Second): ch<-false } }(url) } return <-ch } func main() { fmt.Println(IsReachable([]string{"url1"})) }

Please take a look at this example . As you can see, some sort of event is constantly being sent to the client. I want to imitate this using Django-Channels , inside consumers.py . Here's a simplified version of what I have: class ChatConsumer(AsyncConsumer): async def ws_connect(self, event): self.send = get_db_object() .... await self.send({ "type": "websocket.accept" }) # I need to CONSTANTLY receive & send data async def ws_receive(self, event): obj = ...# query DB and get the newest object json_obj = { 'field_1': obj.field_1, 'field_2': obj.field_2, } await self.send({ "type": "websocket