Tutorial by Examples: s

Let's say we have the following data: >>> data = {"cats": [{"name": "Tubbs", "color": "white"}, {"name": "Pepper", "color": "black"}]} Just dumping this as JSON does not do anything special here: ...

To setup Emacs for working with Clojure, install clojure-mode and cider package from melpa: M-x package-install [RET] clojure-mode [RET] M-x package-install [RET] cider [RET] Now when you open a .clj file, run M-x cider-jack-in to connect to a REPL. Alternatively, you can use C-u M-x (cider-jac...

All built-in Clojure collections are immutable and heterogeneous, have literal syntax, and support the conj, count, and seq functions. conj returns a new collection that is equivalent to an existing collection with an item "added", in either "constant" or logarithmic time. Wha...

A list is denoted by parentheses: () ;;=> () A Clojure list is a singly linked list. conj "conjoins" a new element to the collection in the most efficient location. For lists, this is at the beginning: (conj () :foo) ;;=> (:foo) (conj (conj () :bar) :foo) ;;=> (:foo :ba...

A sequence is very much like a list: it is an immutable object that can give you its first element or the rest of its elements in constant time. You can also construct a new sequence from an existing sequence and an item to stick at the beginning. You can test whether something is a sequence using ...

A vector is denoted by square brackets: [] ;;=> [] [:foo] ;;=> [:foo] [:foo :bar] ;;=> [:foo :bar] [1 (+ 1 1) 3] ;;=> [1 2 3] In addition using to the literal syntax, you can also use the vector function to construct a vector: (vector) ;;=> [] (vector :foo) ;;=&...

Like maps, sets are associative and unordered. Unlike maps, which contain mappings from keys to values, sets essentially map from keys to themselves. A set is denoted by curly braces preceded by an octothorpe: #{} ;;=> #{} #{:foo} ;;=> #{:foo} #{:foo :bar} ;;=> #{:bar :foo} As...

Unlike the list, which is a sequential data structure, and the vector, which is both sequential and associative, the map is exclusively an associative data structure. A map consists of a set of mappings from keys to values. All keys are unique, so maps support "constant"-time lookup from k...

For if you have to fine-tune what is published. import { Mongo } from 'meteor/mongo'; import { Meteor } from 'meteor/meteor'; import { Random } from 'meteor/random'; if (Meteor.isClient) { // established this collection on the client only. // a name is required (first parameter) and this...

On the server, you can create a publication like this. this.userId is the id of the user who is currently logged in. If no user is logged in, you might want to throw an error and respond to it. import Secrets from '/imports/collections/Secrets'; Meteor.publish('protected_data', function () { ...

Swift 3 let stackView = UIStackView() stackView.axis = .horizontal stackView.alignment = .fill // .leading .firstBaseline .center .trailing .lastBaseline stackView.distribution = .fill // .fillEqually .fillProportionally .equalSpacing .equalCentering let label = UILabel() label.text = "...

Swift let stackView = UIStackView() stackView.axis = .Vertical stackView.alignment = .Fill // .Leading .FirstBaseline .Center .Trailing .LastBaseline stackView.distribution = .Fill // .FillEqually .FillProportionally .EqualSpacing .EqualCentering let label = UILabel(frame: CGRectZero) label....

You can take a snapshot from a UIView like this: Swift let snapshot = view.snapshotView(afterScreenUpdates: true) Objective-C UIView *snapshot = [view snapshotViewAfterScreenUpdates: YES];

Using the dateutil library as in the previous example on parsing timezone-aware timestamps, it is also possible to parse timestamps with a specified "short" time zone name. For dates formatted with short time zone names or abbreviations, which are generally ambiguous (e.g. CST, which coul...

By default all datetime objects are naive. To make them timezone-aware, you must attach a tzinfo object, which provides the UTC offset and timezone abbreviation as a function of date and time. Fixed Offset Time Zones For time zones that are a fixed offset from UTC, in Python 3.2+, the datetime mod...

It is often helpful to have MATLAB print the 1st line of a function, as this usually contains the function signature, including inputs and outputs: dbtype <functionName> 1 Example: >> dbtype fit 1 1 function [fitobj,goodness,output,warnstr,errstr,convmsg] = fit(xdatain,ydatain,f...

You can commit changes made to specific files and skip staging them using git add: git commit file1.c file2.h Or you can first stage the files: git add file1.c file2.h and commit them later: git commit

The boolean type cannot be cast to/from any other primitive type. A char can be cast to/from any numeric type by using the code-point mappings specified by Unicode. A char is represented in memory as an unsigned 16-bit integer value (2 bytes), so casting to byte (1 byte) will drop 8 of those bits (...

Numeric primitives can be cast in two ways. Implicit casting happens when the source type has smaller range than the target type. //Implicit casting byte byteVar = 42; short shortVar = byteVar; int intVar = shortVar; long longVar = intvar; float floatVar = longVar; double doubleVar = floatVar...

As with primitives, objects can be cast both explicitly and implicitly. Implicit casting happens when the source type extends or implements the target type (casting to a superclass or interface). Explicit casting has to be done when the source type is extended or implemented by the target type (ca...