Tutorial by Examples: r

# create the co-process coproc bash # send a command to it (echo a) echo 'echo Hello World' >&"${COPROC[1]}" # read a line from its output read line <&"${COPROC[0]}" # show the line echo "$line" The output is "Hello World".
C:\makefile: helloWorld : [TAB]echo hello world run results: C:\>make echo hello world hello world Note: [TAB] should be replaced by an actual tab, stackoverflow replaces tabs with spaces, and spaces are not used the same as tabs in a makefile.
Convert from wide form to long form Load data USArrests from datasets. data("USArrests") head(USArrests) Murder Assault UrbanPop Rape Alabama 13.2 236 58 21.2 Alaska 10.0 263 48 44.5 Arizona 8.1 294 80 31.0 Arkansas 8...
Convert from long form to wide form To recover data from the previous example, use dcast like so. DTc <- dcast(DTmu, State + UrbanPop ~ Crime) This gives the data in the original wide form. State UrbanPop Murder Assault Rape 1: Alabama 58 13.2 236 21.2 2:...
Loop FOR works on similar rules as other loops. FOR loop is executed exact number of times and this number is known at the beginning - lower and upper limits are directly set in code. In every step in this example, loop is increment by 1. Simple example: DECLARE v_counter NUMBER(2); --declaration...
When a new documentation tag is created, StackOverflow automatically generates an introductory topic, acting as a placeholder for the first actual topic. The introductory topic contains placeholder texts and pointers to point contributors in the right directions for helping expanding on the new doc...
Nginx configuration to detect request from mobile user-agent and redirect them to mobile site. location / { #mobile site handling as per user agent set $mobile_rewrite do_not_perform; // variable to store action. default set to not perform redirection to mobile site. if ($htt...
@at-root directive can be used to localize variables. $color: blue; @at-root { $color: red; .a { color: $color; } .b { color: $color; } } .c { color: $color; } is compiled to: .a { color: red; } .b { color: red; } .c { color: blue; }
In many application it is necessary to compute the function of two or more arguments. Traditionally, we use for-loops. For example, if we need to calculate the f = exp(-x^2-y^2) (do not use this if you need fast simulations): % code1 x = -1.2:0.2:1.4; y = -2:0.25:3; for nx=1:lenght(x) for n...
Traditionally, you can use routing to map an the request with the Routing Component who handled request and response parameters by HttpFoundation Component. Additionally, a custom route parameter can be created by using the FOSRestBundle to extends the default functionalities of the Routing Compone...
Custom matchers can be added in jasmine using the syntax: jasmine.addMatchers([ toMatch: function () { return { compare: function (actual, expected) { return { pass: actual===expected, message: "Expected actual to match expected...
Protractor can selectively run groups of tests using fdescribe() instead of describe(). fdescribe('first group',()=>{ it('only this test will run',()=>{ //code that will run }); }); describe('second group',()=>{ it('this code will not run',()=>{ //code...
Custom matchers will have their pass value negated when using 'not'. Custom matchers can have a negative compare attribute to explicitly handle cases where their negation is desired: toMatch: function () { return { compare: function (actual, expected) { return...
Time complexity is a property of Problems someone might want to solve computationally, Algorithms designed to solve such problems and Programs implementing such algorithms. An abstract concept requires no installation or setup. Simply take any problem, algorithm, or code and ask "How lo...
This uses the Dropbox Java SDK to download a file from the Dropbox API at the remote path /Homework/math/Prime_Numbers.txt to the local file Prime_Numbers.txt: String localPath = "Prime_Numbers.txt"; OutputStream outputStream = new FileOutputStream(localPath); FileMetadata metadata = cl...
Many real-world database tables have many rows with DATETIME OR TIMESTAMP column values spanning a lot of time, including years or even decades. Often it's necessary to use a WHERE clause to retrieve some subset of that timespan. For example, we might want to retrieve rows for the date 1-September-2...
echo "Hello, world!" Even in bash, this program works similarly in most other languages. The program has no input and will always function the same in an idealized world - run time should never change. Thus Hello World has constant complexity. Almost all elementary operations are assum...
image: jangrewe/gitlab-ci-android before_script: - apt-get --quiet update --yes - apt-get --quiet install --yes wget tar unzip lib32stdc++6 lib32z1 openjdk-8-jdk - echo y | ${ANDROID_HOME}/tools/android --silent update sdk --no-ui --all --filter android-24 - echo y | ${ANDROID_HOME}/too...
// Set up Express var express = require('express'); var app = express(); // Serve static assets from both 'public' and 'files' directory app.use(express.static('public'); app.use(express.static('files'); // Start Express server app.listen(3030);
// Set up Express var express = require('express'); var app = express(); // Specify mount path, '/static', for the static directory app.use('/static', express.static('public')); // Start Express server app.listen(3030);

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