The Bioconductor package RBGL (an R interface to the BOOST graph library) contains a function, connectedComp(), which identifies the connected components in a graph — just what you are wanting. (To use the function, you will first need to install the graph and RBGL packages, available here and here.) library(RBGL) test <- data.frame(id1=c(10,10,1,1,24,8),id2=c(1,36,24,45,300,11)) ## Convert … Read more
You may keep it in KeyChain -(NSString *)getUniqueDeviceIdentifierAsString { NSString *appName=[[[NSBundle mainBundle] infoDictionary] objectForKey:(NSString*)kCFBundleNameKey]; NSString *strApplicationUUID = [SSKeychain passwordForService:appName account:@”incoding”]; if (strApplicationUUID == nil) { strApplicationUUID = [[[UIDevice currentDevice] identifierForVendor] UUIDString]; [SSKeychain setPassword:strApplicationUUID forService:appName account:@”incoding”]; } return strApplicationUUID; }
Having 2 elements with the same ID is not valid html according to the W3C specification. When your CSS selector only has an ID selector (and is not used on a specific context), jQuery uses the native document.getElementById method, which returns only the first element with that ID. However, in the other two instances, jQuery … Read more
The basic idea is that you have two numbers to make up a primary key- a “high” number and a “low” number. A client can basically increment the “high” sequence, knowing that it can then safely generate keys from the entire range of the previous “high” value with the variety of “low” values. For instance, … Read more
We call them references. They work like this i = 5 # create int(5) instance, bind it to i j = i # bind j to the same int as i j = 3 # create int(3) instance, bind it to j print i # i still bound to the int(5), j bound to the … Read more
It depends on which spec you read. 🙂 This behavior is not described by the HTML4 specification (c.f., http://www.w3.org/TR/1999/REC-html401-19991224/struct/global.html#adef-id and http://www.w3.org/TR/1999/REC-html401-19991224/types.html#type-name). However, it was introduced by Internet Explorer and then copied in other major browsers for compatibility. FireFox also displays this behavior, but only in quirks mode (and even then its implementation seems buggy). The … Read more
This can be further simplified and improved: CREATE OR REPLACE FUNCTION some_f(_tbl regclass, OUT result integer) LANGUAGE plpgsql AS $func$ BEGIN EXECUTE format(‘SELECT (EXISTS (SELECT FROM %s WHERE id = 1))::int’, _tbl) INTO result; END $func$; Call with schema-qualified name (see below): SELECT some_f(‘myschema.mytable’); — would fail with quote_ident() Or: SELECT some_f(‘”my very uncommon table … Read more
Identifiers (including column names) that are not double-quoted are folded to lowercase in PostgreSQL. Column names that were created with double-quotes and thereby retained uppercase letters (and/or other syntax violations) have to be double-quoted for the rest of their life: “first_Name” Values (string literals / constants) are enclosed in single quotes: ‘xyz’ So, yes, PostgreSQL … Read more
Single Underscore Names, in a class, with a leading underscore are simply to indicate to other programmers that the attribute or method is intended to be private. However, nothing special is done with the name itself. To quote PEP-8: _single_leading_underscore: weak “internal use” indicator. E.g. from M import * does not import objects whose name … Read more