lambda

问题 I have a repository class which has a GetAsQueryable method defined as follows: public class Repository<TEntity> : IDisposable, IRepository<TEntity> where TEntity : class { internal DbSet<TEntity> _DbSet; public virtual IQueryable<TEntity> GetAsQueryable( Expression<Func<TEntity, bool>> filter = null, Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null, string includeProperties = "") { IQueryable<TEntity> query = _DbSet; if (filter != null) { query = query.Where(filter); }

问题 I have a situation where I have a dataframe row to perform calculations with, and I need to use values in following (potentially preceding) rows to do these calculations (essentially a perfect forecast based on the real data set). I get each row from an earlier df.apply call, so I could pass the whole df along to the downstream objects, but that seems less than ideal based on the complexity of objects in my analysis. I found one closely related question and answer [1], but the problem is

问题 I am Python newbie, and just become very interested in Lambda expression. The problem I have is to find one and only one target element from a list of elements with lambda filter. In theory, when the target element is found there is no sense to continue anymore. With for loop it is pretty simple to break the loop, but what about by using lambda ? is it after all possible to do this? I search from Google, but did not find the expected solution 回答1: From https://docs.python.org/3/library

问题 I am Python newbie, and just become very interested in Lambda expression. The problem I have is to find one and only one target element from a list of elements with lambda filter. In theory, when the target element is found there is no sense to continue anymore. With for loop it is pretty simple to break the loop, but what about by using lambda ? is it after all possible to do this? I search from Google, but did not find the expected solution 回答1: From https://docs.python.org/3/library

问题 I want to wrap a callable of any type (e.g. a lambda) transparently inside another callable to inject additional functionality. The wrapper's type should have the same characteristics as the original callable: Identical parameter types Identical return type Perfect forwarding of passed arguments Same behaviour when used in SFINAE constructs I attempted to use generic variadic lambdas as wrappers: #include <iostream> #include <type_traits> template<class TCallable> auto wrap(TCallable&&

问题 I want to wrap a callable of any type (e.g. a lambda) transparently inside another callable to inject additional functionality. The wrapper's type should have the same characteristics as the original callable: Identical parameter types Identical return type Perfect forwarding of passed arguments Same behaviour when used in SFINAE constructs I attempted to use generic variadic lambdas as wrappers: #include <iostream> #include <type_traits> template<class TCallable> auto wrap(TCallable&&

问题 How exactly do you chain method references for instances with Java 8? Example: Collections.sort(civs,Comparator.comparing(Civilization::getStrategy.getStrategLevel)); getStrategy of a Civilization instance returns a Strategy object instance which has the instance method getStrategyLevel . Why doesn't the Comparator.comparing method return a comparator with it's functional interface implemented by the lambda expression? 回答1: In that case, you should use a lambda, you can't apply a method

问题 I am writing a python script that analyses a piece of text and returns the data in JSON format. I am using NLTK, to analyze the data. Basically, this is my flow: Create an endpoint (API gateway) -> calls my lambda function -> returns JSON of required data. I wrote my script, deployed to lambda but I ran into this issue: Resource \u001b[93mpunkt\u001b[0m not found. Please use the NLTK Downloader to obtain the resource: \u001b[31m>>> import nltk nltk.download('punkt') \u001b[0m Searched in: - '

问题 I am writing a python script that analyses a piece of text and returns the data in JSON format. I am using NLTK, to analyze the data. Basically, this is my flow: Create an endpoint (API gateway) -> calls my lambda function -> returns JSON of required data. I wrote my script, deployed to lambda but I ran into this issue: Resource \u001b[93mpunkt\u001b[0m not found. Please use the NLTK Downloader to obtain the resource: \u001b[31m>>> import nltk nltk.download('punkt') \u001b[0m Searched in: - '

问题 I would like to filter an array into an array of every nth item. For examples: fun getNth(array: Array<Any>, n: Int): Array<Any> { val newList = ArrayList<Any>() for (i in 0..array.size) { if (i % n == 0) { newList.add(array[i]) } } return newList.toArray() } Is there an idiomatic way to do this using for example Kotlin's .filter() and without A) provisioning a new ArrayList and B) manually iterating with a for/in loop? 回答1: filterIndexed function is suited exactly for this case: array