collect

I am using Rails 3.2.2 and I would like to quote all array elements with ' and return a string containing all those quoted and comma-separated elements. At this time I am using ['a', 'b', 'c'].collect {|x| "'#{x}'"}.join(", ") # => "'a', 'b', 'c'" but I think I can improve the above code (maybe by using a unknown to me Ruby method, if it exists). Is it possible? I use "'#{%w{a b c}.join("', '")}'" Here is expanded version: ' # Starting quote %w{a b c}.join("', '") # Join array with ', ' delimiter that would give a', 'b', 'c ' # Closing quote N.N. You can replace collect with its alias map and

I have an array of hashes Eg: cars = [{:company => "Ford", :type => "SUV"}, {:company => "Honda", :type => "Sedan"}, {:company => "Toyota", :type => "Sedan"}] # i want to fetch all the companies of the cars cars.collect{|c| c[:company]} # => ["Ford", "Honda", "Toyota"] # i'm lazy and i want to do something like this cars.collect(&:company) # => undefined method `company' I was wondering if there is a similar shortcut to perform the above. I believe your current code cars.collect{|c| c[:company]} is the best way if you're enumerating over an arbitrary array. The method you would pass in via the

Lets say we have this boring piece of code that we all had to use: ArrayList<Long> ids = new ArrayList<Long>(); for (MyObj obj : myList){ ids.add(obj.getId()); } After switching to Java 8, my IDE is telling me that I can replace this code with collect call , and it auto-generates: ArrayList<Long> ids = myList.stream().map(MyObj::getId).collect(Collectors.toList()); However its giving me this error: collect(java.util.stream.Collector) in Steam cannot be applied to: (java.util.stream.Collector, capture, java.util.List>) I tried casting the parameter but its giving me undefined A and R , and the

I need your advice to simplify this code below. I have a player list with an ID of the games won. I want to extract the 2 best players from this list (the 2 players who have a better amount of match Id) Once extracted, I have to return the initial list to do other operations. I think it is possible to improve this code in terms of optimization or reading. If you can help me. public class PlayerStatistics { int id String name; int idMatchWon; // key from Match // getter , setter } public static void main(String[] args) throws Exception { List<PlayerStatistics> _players = new ArrayList

In Ruby, what is the most expressive way to map an array in such a way that certain elements are modified and the others left untouched ? This is a straight-forward way to do it: old_a = ["a", "b", "c"] # ["a", "b", "c"] new_a = old_a.map { |x| (x=="b" ? x+"!" : x) } # ["a", "b!", "c"] Omitting the "leave-alone" case of course if not enough: new_a = old_a.map { |x| x+"!" if x=="b" } # [nil, "b!", nil] What I would like is something like this: new_a = old_a.map_modifying_only_elements_where (Proc.new {|x| x == "b"}) do |y| y + "!" end # ["a", "b!", "c"] Is there some nice way to do this in Ruby

when I am trying to run it on this folder it is throwing me ExecutorLostFailure everytime Hi I am a beginner in Spark. I am trying to run a job on Spark 1.4.1 with 8 slave nodes with 11.7 GB memory each 3.2 GB Disk . I am running the Spark task from one of the slave node (from 8 nodes) (so with 0.7 storage fraction approx 4.8 gb only is available on each node )and using Mesos as the Cluster Manager. I am using this configuration : spark.master mesos://uc1f-bioinfocloud-vamp-m-1:5050 spark.eventLog.enabled true spark.driver.memory 6g spark.storage.memoryFraction 0.7 spark.core.connection.ack