Tutorial by Examples: int

Parameters Nullable type hint was added in PHP 7.1 using the ? operator before the type hint. function f(?string $a) {} function g(string $a) {} f(null); // valid g(null); // TypeError: Argument 1 passed to g() must be of the type string, null given Before PHP 7.1, if a parameter has a typ...
Example Controller action use Symfony\Component\HttpFoundation\Request; public function exampleAction(Request $request) { /* * First you need object ready for validation. * You can create new object or load it from database. * You need to add some constraints for this obj...
import pandas as pd df = pd.DataFrame([{'var1': 'a,b,c', 'var2': 1, 'var3': 'XX'}, {'var1': 'd,e,f,x,y', 'var2': 2, 'var3': 'ZZ'}]) print(df) reshaped = \ (df.set_index(df.columns.drop('var1',1).tolist()) .var1.str.split(',', expand=True) .stack() .reset_ind...
Loading from string Use simplexml_load_string to create a SimpleXMLElement from a string: $xmlString = "<?xml version='1.0' encoding='UTF-8'?>"; $xml = simplexml_load_string($xmlString) or die("Error: Cannot create object"); Note that or not || must be used here becau...
Let say you want to build your API to comply jsonapi.org specification and the result should look like: { "article": { "id": "305", "type": "articles", "attributes": { "title": "Asking Alexandria&q...
An integer literal is a primary expression of the form decimal-literal It is a non-zero decimal digit (1, 2, 3, 4, 5, 6, 7, 8, 9), followed by zero or more decimal digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) int d = 42; octal-literal It is the digit zero (0) followed by zero or more octal dig...
If you have a Javascript timestamp value, for example 1478960868932, you can convert that to a MySQL fractional time value like this: FROM_UNIXTIME(1478960868932 * 0.001) It's simple to use that kind of expression to store your Javascript timestamp into a MySQL table. Do this: INSERT INTO table...
Code coverage is a measure used to how often each source code statement and branch is executed. This measure is usually required when running a test suite to ensure that as much of the code as possible is tested by the test suite. It can also be used during profiling to determine code hot-spots and ...
Suppose that we have a text and a pattern. We need to determine if the pattern exists in the text or not. For example: +-------+---+---+---+---+---+---+---+---+ | Index | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | +-------+---+---+---+---+---+---+---+---+ | Text | a | b | c | b | c | g | l | x | +-------...
Suppose we have an array: +-------+-----+-----+-----+-----+-----+-----+ | Index | 0 | 1 | 2 | 3 | 4 | 5 | +-------+-----+-----+-----+-----+-----+-----+ | Value | -1 | 3 | 4 | 0 | 2 | 1 | +-------+-----+-----+-----+-----+-----+-----+ We want to perform some query on thi...
Dynamic programming solves problems by combining the solutions to subproblems. It can be analogous to divide-and-conquer method, where problem is partitioned into disjoint subproblems, subproblems are recursively solved and then combined to find the solution of the original problem. In contrast, dyn...
Eloquent relationships are defined as functions on your Eloquent model classes. Since, like Eloquent models themselves, relationships also serve as powerful query builders, defining relationships as functions provides powerful method chaining and querying capabilities. For example, we may chain addi...
Dynamic Time Warping(DTW) is an algorithm for measuring similarity between two temporal sequences which may vary in speed. For instance, similarities in walking could be detected using DTW, even if one person was walking faster than the other, or if there were accelerations and decelerations during ...
We have a set of jobs J={a,b,c,d,e,f,g}. Let j in J be a job than its start at sj and ends at fj. Two jobs are compatible if they don't overlap. A picture as example: The goal is to find the maximum subset of mutually compatible jobs. There are several greedy approaches for this problem: Earli...
In the view file In the base html (index.html) where we usually include the angular scripts or the html that is shared across the app, leave an empty div element, the flash messages will be appearing inside this div element <div class="flashmessage" ng-if="isVisible"> ...
Viridis (named after the chromis viridis fish) is a recently developed color scheme for the Python library matplotlib (the video presentation by the link explains how the color scheme was developed and what are its main advantages). It is seamlessly ported to R. There are 4 variants of color scheme...
The package colorspace provides GUI for selecting a palette. On the call of choose_palette() function the following window pops-up: When the palette is chosen, just hit OK and do not forget to store the output in a variable, e.g. pal. pal <- choose_palette() The output is a function that t...
In [1]: df = pd.DataFrame({'A': [1, 2, 3], 'B': [1.0, 2.0, 3.0], 'C': ['a', 'b', 'c'], 'D': [True, False, True]}) In [2]: df Out[2]: A B C D 0 1 1.0 a True 1 2 2.0 b False 2 3 3.0 c True Getting a python list from a series: In [3]: df['...
Joda-Time is a robust alternative to the Java date and time classes. Prior to Java SE 8, the standard Java date and time classes like java.util.Calendar are difficult to use and prone to errors. Joda-Time emerged as the de-facto standard library for date and time manipulation in many open-source-pr...
$a1 = array("red","green"); $a2 = array("blue","yellow"); print_r(array_merge($a1,$a2)); /* Array ( [0] => red [1] => green [2] => blue [3] => yellow ) */ Associative array: $a1=array("a"=>"red","b"=&...

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