grepl function in r

Compile a function. When n is an even number, call the function to calculate 1/2 + 1/4 +... + 1/n. When n is an odd number, call the function 1/1 + 1/3 +... + 1/n ., Even number First, write a function whose n is an even number: Def peven (n): s = 0.0 for I in range (2, n + 1.0): s + =/I print 'value:', s Write anot

description of method callback for PHP class static functions and objects Some of the previous chapters are declared and applied by global functions (which do not have functions defined in any object or class), but are different if static methods in the callback class are encountered, or ordinary methods in the object. Object-oriented technology will be described in detail in the chapters later in this book, so for this section of this application, you can go back to the learning and applicatio

Call CreateThread (...) To specify the entry function of the created thread when the thread is created, this entry function can only be a global function or a static member function of a class.The global function is easy to understand, but if the member

The fourth argument of Qsort, the compare of the auxiliary function, is the different ways of ordering objects:First, sort an array of type intint num[]; int Compare (constvoidconstvoid *b) { return * ( int *) A-* (int *) b;}Second, sort the array of char types (same as int type)Char word[]; int Compare (constvoidconstvoid *b) { return * ( Char *) A-* (int *) b;}Third, sort the array of double typedouble array[]; int Compare (constvoidconstvoid *b

#include Assert assert () "header file" #include For example: Assert (NAssertion: Expressed as some boolean expression, the programmer believes that the expression value is true at a particular point in the program and can enable and disable assertion validation at any time, so you can enable assertions at test time and disable assertions at deployment time. Similarly, the end user can re-enable assertions when a problem is encountered after the program is put into operation.Assertions can only

Tags: hello BST binary return result SQL function return nbsp HTTP charDB2 left , right functionSyntax: Left (arg,length), right (Arg,length)The left and right functions return the leftmost, rightmost length string of arg, which can be a char or binary string.egSELECT Left (name,2), right (name,2) from T1ORACLE substr () functionSUBSTR (string, intercept start position, intercept length)//return intercepted wordsubstr (' Hello World ', 0, 1)//return r

This article mainly introduces the round function code in PHP (floor function, ceil function, round and intval), has a certain reference value, now share to everyone, the need for friends can refer to When working with floating-point numbers in PHP, you often need to round up. There are two functions in PHP that apply to this scenario: floor

Introduction to Opacity functionsIn addition to using Rgba,Hsla , and transform to control color transparency in CSS, you can use opacity to control it, except that the first two are only for color transparent channels are processed, while the latter controls the transparency of the entire element .In Sass, a series of transparent functions are provided, except that this series of transparent functions are mainly used to deal with color transparency: Alpha ($color)/opacity ($color): Get

built-in functions /built-in function or Method There are many built-in functions in Python (see the 3.6.1 section), where the built-in functions are described built-in functions ord/built-in function ord Python's built-in function, Ord, is to convert a single character in an ASCII code table to the corresponding decimal integer data .>>> Ord ('b') 98 >>> ord

Convex Function A convex function is a continuous function whose value at the midpoint of every interval in its domain does not exceed the Arithmetic mean of its values at the ends of the interval. More generally, a function was convex on a interval if to any two points and where, (Rudin 1976, p. Cf. Gradshteyn and Ryz

Code of the rounding function in php (floor function, ceil function, round and intval), ceilintval The combination of the floor function and the ceil function makes the data processed by php more authentic and reliable. I. First, let's look at the floor

1. Virtual function (impure virtual)The virtual function of C + + has the function of " runtime polymorphism ", which provides the implementation of virtual function in the parent class, and provides the default function implementation for subclasses .　　Subclasses can overri

Introduction to the getattr function hasattr function and getattrhasattr function in python Hasattr (object, name) Purpose:Determine whether the object contains the feature named name (hasattr is implemented by calling getattr (ojbect, name) to check whether an exception is thrown ). Example: >>> hasattr(list, 'append')True >>> hasattr(list, 'add')False Getattr (

The writes a sort function to sort the numbers. The sorting method is implemented by the client function, the number of function parameters is two, the relationship of two parameters is the relationship between the sorted elements.

Read the program:#include Operation Result:Enter the code:/* Copyright (c) 2014, Yantai University School of Computer * All rights reserved. * File name: Sum123.cpp * Author: Lin Haiyun * Completion Date: April 15, 2015 * Version number: v2.0 * * Problem Description: The difference between this project and an example is that "distance is the distance between a point and another point", and different versions are reflected in the parameters. The three versions suggest separate testing, or,

JS Call function when the parentheses add to the difference, function () function