enumerable

问题 This question already has an answer here: what's different between each and collect method in Ruby [duplicate] 7 answers In Ruby, is there any difference between the functionalities of each , map , and collect ? 回答1: each is different from map and collect , but map and collect are the same (technically map is an alias for collect , but in my experience map is used a lot more frequently). each performs the enclosed block for each element in the ( Enumerable ) receiver: [1,2,3,4].each {|n| puts

问题 I have an array of hashes: [{\"Vegetable\"=>10}, {\"Vegetable\"=>5}, {\"Dry Goods\"=>3>}, {\"Dry Goods\"=>2}] I need to use inject here I think but I\'ve really been struggling. I want a new hash that reflects the sum of the previous hash\'s duplicate keys: [{\"Vegetable\"=>15}, {\"Dry Goods\"=>5}] I\'m in control of the code that outputs this hash so I can modify it if necessary. The results were mainly hashes because this could end up nested any number of levels deep and then it\'s easy to

问题 I have the following method: public bool IsValid { get { return (GetRuleViolations().Count() == 0); } } public IEnumerable<RuleViolation> GetRuleViolations(){ //code here } Why is it that when I do .Count() above it is underlined in red? I got the following error: Error 1 \'System.Collections.Generic.IEnumerable\' does not contain a definition for \'Count\' and no extension method \'Count\' accepting a first argument of type \'System.Collections.Generic.IEnumerable\' could be found (are you

问题 Reading the questions here and here has given me some insight into the situation, and it seems like using the AsEnumerable is memory consuming. Is there a better way to do this LINQ and the way it is done now, is the data that comes out reliable? Removing the AsEnumerable results in a \"Local sequence cannot be used in LINQ to SQL implementations of query operators except the Contains operator.\" var results = from p in pollcards.AsEnumerable() join s in spoils.AsEnumerable() on new { Ocr = p

问题 This question already has an answer here: Why does IQueryable.All() return true on an empty collection? 11 answers var strs = new Collection<string>(); bool b = strs.All(str => str == \"ABC\"); The code creates an empty collection of string, then tries to determine if all the elements in the collection are \"ABC\". If you run it, b will be true. But the collection does not even have any elements in it, let alone any elements that equal to \"ABC\". Is this a bug, or is there a reasonable

问题 I was directed to MDN\'s for..in page when it said, \"for..in Iterates over the enumerable properties of an object.\" Then I went to the Enumerability and ownership of properties page where it said \"Enumerable properties are those which can be iterated by a for..in loop.\" The dictionary defines enumerable as countable, but I can\'t really visualize what that means. Could i get an example of something being enumerable? 回答1: An enumerable property is one that can be included in and visited

问题 A new feature in C# / .NET 4.0 is that you can change your enumerable in a foreach without getting the exception. See Paul Jackson\'s blog entry An Interesting Side-Effect of Concurrency: Removing Items from a Collection While Enumerating for information on this change. What is the best way to do the following? foreach(var item in Enumerable) { foreach(var item2 in item.Enumerable) { item.Add(new item2) } } Usually I use an IList as a cache/buffer until the end of the foreach , but is there