Tutorial by Examples: r

You can use buffers to work with multiple files. When you open a file using :e path/to/file it opens in a new buffer (the command means edit the file). New buffer that holds a temporary copy of the file. You can go to previous buffer with :bp[rev] and next buffer with :bn[ext]. You can go to a...

Commands have one input (STDIN) and two kinds of outputs, standard output (STDOUT) and standard error (STDERR). For example: STDIN root@server~# read Type some text here Standard input is used to provide input to a program. (Here we're using the read builtin to read a line from STDIN.) STDO...

{ echo "contents of home directory" ls ~ } > output.txt

The ternary operator can be thought of as an inline if statement. It consists of three parts. The operator, and two outcomes. The syntax is as follows: $value = <operator> ? <true value> : <false value> If the operator is evaluated as true, the value in the first block will be ...

It is possible to effectively apply a function (cb) which returns a promise to each element of an array, with each element waiting to be processed until the previous element is processed. function promiseForEach(arr, cb) { var i = 0; var nextPromise = function () { if (i >= arr.leng...

The ember data models have a toJSON method that extracts the relevant data: console.log(model.toJSON()); This method uses the JSONSerializer to create the JSON representation. If you want to log the data in a more app-specific way, you can use serialize: model.serialize(); which uses the se...

Ember has a static global method called runInDebug which can run a function meant for debugging. Ember.runInDebug(() => { // this code only runs in dev mode }); In a production build, this method is defined as an empty function (NOP). Uses of this method in Ember itself are stripped from ...

import pandas as pd df = pd.DataFrame({'gender': ["male", "female","female"], 'id': [1, 2, 3] }) >>> df gender id 0 male 1 1 female 2 2 female 3 To encode the male to 0 and female to 1: df.loc[df["gender&quot...

import pandas as pd df = pd.DataFrame(np.random.randn(5, 5), columns=list('ABCDE')) To generate various summary statistics. For numeric values the number of non-NA/null values (count), the mean (mean), the standard deviation std and values known as the five-number summary : min: minimum (smal...

Supported by IE11+ View Result Use these 3 lines to vertical align practically everything. Just make sure the div/image you apply the code to has a parent with a height. CSS div.vertical { position: relative; top: 50%; transform: translateY(-50%); } HTML <div class="vertica...

Clojure uses prefix notation, that is: The operator comes before its operands. For example, a simple sum of two numbers would be: (+ 1 2) ;; => 3 Macros allow you to manipulate the Clojure language to a certain degree. For example, you could implement a macro that let you write code in infi...

Ring is de-facto standard API for clojure HTTP applications, similar to Ruby's Rack and Python's WSGI. We're going to use it with http-kit webserver. Create new Leiningen project: lein new app myapp Add http-kit dependency to project.clj: :dependencies [[org.clojure/clojure "1.8.0&quot...

The cubic-bezier function is a transition timing function which is often used for custom and smooth transitions. transition-timing-function: cubic-bezier(0.1, 0.7, 1.0, 0.1); The function takes four parameters: cubic-bezier(P1_x, P1_y, P2_x, P2_y) These parameters will be mapped to points whic...

The following method computes the sum of integers from 0 to N using recursion. public int sum(final int n) { if (n > 0) { return n + sum(n - 1); } else { return n; } } This method is O(N) and can be reduced to a simple loop using tail-call optimization. In f...

The following method computes the value of num raised to the power of exp using recursion: public long power(final int num, final int exp) { if (exp == 0) { return 1; } if (exp == 1) { return num; } return num * power(num, exp - 1); } This illustrates ...

<root xmlns="http://test/"> <element xmlns:example="http://foobar/"> <example:hello_world attribute="another example" /> </element> </root> The expression /root will return nothing, because there is no non-namespaced ...

Any predicate function can be used as a spec. Here's a simple example: (clojure.spec/valid? odd? 1) ;;=> true (clojure.spec/valid? odd? 2) ;;=> false the valid? function will take a spec and a value and return true if the value conforms to the spec and false otherwise. One other inte...

Let's say we have the following function: (defn nat-num-count [nums] (count (remove neg? nums))) We can write a spec for this function by defining a function spec of the same name: (clojure.spec/fdef nat-num-count :args (s/cat :nums (s/coll-of number?)) :ret integer? ...

Hibernate can use two types of fetch when you are mapping the relationship between two entities: EAGER and LAZY. In general, the EAGER fetch type is not a good idea, because it tells JPA to always fetch the data, even when this data is not necessary. Per example, if you have a Person entity and th...

While there are many parameters that can be changed and variations that can be added depending on the desired functionality, this example lays out the basic framework for launching PowerPoint. Note: This code requires that the PowerPoint reference has been added to the active VBA Project. See th...