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s = {1, 2, 3} # get every element in s for a in s: print a # prints 1, then 2, then 3 # copy into list l1 = list(s) # l1 = [1, 2, 3] # use list comprehension l2 = [a * 2 for a in s if a > 2] # l2 = [6]

Use unpacking to extract the first element and ensure it's the only one: a, = iterable def foo(): yield 1 a, = foo() # a = 1 nums = [1, 2, 3] a, = nums # ValueError: too many values to unpack

Start with iter() built-in to get iterator over iterable and use next() to get elements one by one until StopIteration is raised signifying the end: s = {1, 2} # or list or generator or even iterator i = iter(s) # get iterator a = next(i) # a = 1 b = next(i) # b = 2 c = next(i) # raises S...

Sort the edges by value and add each one to the MST in sorted order, if it doesn't create a cycle. algorithm kruskalMST(G: a graph) sort G's edges by their value MST = an empty graph for each edge e in G: if adding e to MST does not create a cycle: add e to MST ...

JSON stands for "JavaScript Object Notation", but it's not JavaScript. Think of it as just a data serialization format that happens to be directly usable as a JavaScript literal. However, it is not advisable to directly run (i.e. through eval()) JSON that is fetched from an external source...

1. Target a device by serial number Use the -s option followed by a device name to select on which device the adb command should run. The -s options should be first in line, before the command. adb -s <device> <command> Example: adb devices List of devices attached emulator-55...

' This method is useful for iterating Enum values ' Enum Animal Dog = 1 Cat = 2 Frog = 4 End Enum Dim Animals = [Enum].GetValues(GetType(Animal)) For Each animal in Animals Console.WriteLine(animal) Next Prints: 1 2 4

NSError *e = nil; NSString *jsonString = @"[{\"id\": \"1\", \"name\":\"sam\"}]"; NSData *data = [jsonString dataUsingEncoding:NSUTF8StringEncoding]; NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData: data options: NSJSONReadingMutabl...

Just like in case of the function arguments, template parameters can have their default values. All template parameters with a default value have to be declared at the end of the template parameter list. The basic idea is that the template parameters with default value can be omitted while template ...

Useful if your program is outputting web pages along the way. from http.server import HTTPServer, CGIHTTPRequestHandler import webbrowser import threading def start_server(path, port=8000): '''Start a simple webserver serving path on port''' os.chdir(path) httpd = HTTPServer((''...

Creating empty deque: dl = deque() # deque([]) creating empty deque Creating deque with some elements: dl = deque([1, 2, 3, 4]) # deque([1, 2, 3, 4]) Adding element to deque: dl.append(5) # deque([1, 2, 3, 4, 5]) Adding element left side of deque: dl.appendleft(0) # deque([0, 1, 2, ...

String to a primitive numeric type or a numeric wrapper type: Each numeric wrapper class provides a parseXxx method that converts a String to the corresponding primitive type. The following code converts a String to an int using the Integer.parseInt method: String string = "59"; int p...

CSS ul { list-style: none; counter-reset: list-item-number; /* self nesting counter as name is same for all levels */ } li { counter-increment: list-item-number; } li:before { content: counters(list-item-number, ".") " "; /* usage of counters() function means val...

<button tabindex="-1">This button will not be reachable by tab</button> The element will be removed from the tabbing order but will still be focusable.

This is a simple but robust core-data set-up for iOS 10+. There are exactly two way to access core-data: viewContext. The viewContext can only be used from the main thread, and only for reading. strong enqueueCoreDataBlock. All writing should be done using enqueueCoreDataBlock. There is no ne...

Get the Source Package from http://typo3.org/download/ and upload this package to your web server. Put it one level above the document root. For this manual, we will use the .tar.gz file. Use the shell to execute the according commands: /var/www/site/htdocs/$ cd .. /var/www/site/$ wget get.typo3....

hashlib.new requires the name of an algorithm when you call it to produce a generator. To find out what algorithms are available in the current Python interpreter, use hashlib.algorithms_available: import hashlib hashlib.algorithms_available # ==> {'sha256', 'DSA-SHA', 'SHA512', 'SHA224', 'dsa...

Let's add a custom operator to multiply a CGSize func *(lhs: CGFloat, rhs: CGSize) -> CGSize{ let height = lhs*rhs.height let width = lhs*rhs.width return CGSize(width: width, height: height) } Now this works let sizeA = CGSize(height:100, width:200) let sizeB = 1.1 * si...

When we have two separate array and we want to make key value pair from that two array, we can use array's reduce function like below: var columns = ["Date", "Number", "Size", "Location", "Age"]; var rows = ["2001", "5", "B...

If realloc fails, it returns NULL. If you assign the value of the original buffer to realloc's return value, and if it returns NULL, then the original buffer (the old pointer) is lost, resulting in a memory leak. The solution is to copy into a temporary pointer, and if that temporary is not NULL, th...