enumerable

I want to know how to transform a DataTable into a Dictionary. I did something like this. using System.Linq; internal Dictionary<string,object> GetDict(DataTable dt) { return dt.AsEnumerable() .ToDictionary<string, object>(row => row.Field<string>(0), row => row.Field<object>(1)); } But I get: System.Data.EnumerableRowCollection does not contains a definition for 'ToDictionary' and the best extension method overload 'System.Linq.Parallel.Enumerable.ToDictionary(System.Linq.ParallelQuery, System.Func, System.Collections.Generic.IEqualityComrparer)' has some invalid argumentsch How can I resolve

What are your favorite code snippets with ruby collections? Preferably they should be discovery for you, be expressive, readable and introduce some fun in your coding practice. Pattern-matching in arrays (for local variables and parameters): (a, b), c = [[:a, :b], :c] [a,b,c] => [:a, :b, :c] (a,), = [[:a]] a => :a Assigning from non-arrays to multiple variables: abc, a, b =* "abc".match(/(a)(b)./) => ["abc", "a", "b"] nil1, =* "abc".match(/xyz/) => [] Initialize array elements with the same expression: 5.times.map { 1 } => [1,1,1,1] Array.new(5) { 1 } => [1,1,1,1,1] Initialize array with the

I'm probably missing something obvious, but is there a way to access the index/count of the iteration inside a hash each loop? hash = {'three' => 'one', 'four' => 'two', 'one' => 'three'} hash.each { |key, value| # any way to know which iteration this is # (without having to create a count variable)? } YOU If you like to know Index of each iteration you could use .each_with_index hash.each_with_index { |(key,value),index| ... } You could iterate over the keys, and get the values out manually: hash.keys.each_with_index do |key, index| value = hash[key] print "key: #{key}, value: #{value}, index

Why does this not iterate? import logging logging.basicConfig(level=logging.DEBUG) x = [] y = [[] for n in range(0, 1)] linedata = ["0","1","2"] x.append( linedata[0] ) d = linedata[1:] logging.debug( "d: {}".format(d) ) e = enumerate(d) logging.debug( list(e) ) for k, v in e: logging.debug( "k:{} v:{}".format( k, v ) ) y[int(k)].append( v ) #for d in [(0,1)]: #logging.debug( "k:{} v:{}".format( d[0], d[1] ) ) #y[d[0]].append( d[1] ) logging.debug( x ) logging.debug( y ) Output: DEBUG:root:d: ['1', '2'] DEBUG:root:[(0, '1'), (1, '2')] DEBUG:root:['0'] DEBUG:root:[[]] Docs: https://docs.python

Say for example I have an enumerable dim e = Enumerable.Range(0, 1024) I'd like to be able to do dim o = e.ToObservable(Timespan.FromSeconds(1)) So that the observable would generate values every second until the enumerable is exhausted. I can't figure a simple way to do this. I have also looked for the solution and after reading the intro to rx made my self one: There is an Observable.Generate() overload which I have used to make my own ToObservable() extension method, taking TimeSpan as period: public static class MyEx { public static IObservable<T> ToObservable<T>(this IEnumerable<T>

I know of Python's list method that can consume all elements from a generator. Is there something like that available in Ruby? I know of : elements = [] enumerable.each {|i| elements << i} I also know of the inject alternative. Is there some ready available method? Enumerable#to_a If you want to do some transformation on all the elements in your enumerable, the #collect (a.k.a. #map) method would be helpful: elements = enumerable.collect { |item| item.to_s } In this example, elements will contain all the elements that are in enumerable , but with each of them translated to a string. E.g.