You can use something like this: a.flat_map{|x| x.in_groups_of(a.max_by(&:size).size, 0)}.transpose.map(&:sum) Or this: a.max_by(&:size).map.with_index{|_, i| a.sum{|x| x[i]||0}} 4 solved Sum of arrays of different size [closed]
Sequential logic is faster (see the benchmark below the fold), but it almost never matters. The clearer and more maintainable code should always be selected. Only a demonstrated need should cause one to cease optimizing for the programmer and begin optimizing for the machine. By demonstrated, I mean measured–you ran it and found it to … Read more
Smells like homework assignment since you specifically request a recursive solution. A solution with recursion is to check whether first equals last letter and if they are recursively check the string in between. An empty or one character string is a palindrome. def palindrome?(str) str.length <= 1 or (str[0,1] == str[-1,1] and palindrome?(str[1..-2])) end solved … Read more
You got that exception because the class String has no instance method each: String.instance_methods.include?(:each) #=> false If packages is a string need to operate on an array comprised of that string alone. We can use the method Kernel#Array to write: Array(packages).each do |package| Array(packages) will return packages if packages is an array and will return … Read more
If you need to convert an IP to a range, you’ll need a function that converts an IPv4 value to an integer, then do math on those: require ‘ipaddr’ def ip(string) IPAddr.new(string).to_i end def parse_ip(string) string.split(/\s+\-\s+/).collect { |v| ip(v) } end def ip_range(string) ips = parse_ip(string) ips.last – ips.first + 1 end ip_range(“10.2.3.10 – 10.2.3.15”) … Read more
Make that 3*a, you left out the actual multiplication. 2 solved Finding the longest collatz sequence for starting numbers < 100
What you have works. Just don’t forget to assign the sorted collection to a variable (sort_by and reverse do not change the collection). Bonus: here’s arguably a nicer version (one pass, instead of two) a.sort_by{ |v| -v[:a_value] } solved Multisort using Ruby [closed]
Introduction The Collatz Conjecture is an unsolved mathematical problem that has been around since 1937. It states that if you take any positive integer and apply a certain set of rules, you will eventually reach 1. The rules are simple: if the number is even, divide it by two; if the number is odd, multiply … Read more
myarray. sort_by { |h| h[‘id’][/\d+/].to_i }. each. with_index(1) do |h, idx| puts [“\n”, “#{idx})”, h[‘id’], “n.”, h[‘count’]].join(‘ ‘) end 2 solved Print an array of hashes ordered by a hash key
Use regex /r\d+=\d+/: “http://test.com?t&r12=1&r122=1&r1=1&r124=1”.scan(/r\d+=\d+/) # => [“r12=1”, “r122=1”, “r1=1”, “r124=1”] “http://test.com?t&r12=1&r124=1”.scan(/r\d+=\d+/) # => [“r12=1”, “r124=1”] You can use join to get a string output. Here: “http://test.com?t&r12=1&r122=1&r1=1&r124=1”.scan(/r\d+=\d+/).join(‘,’) # => “r12=1,r122=1,r1=1,r124=1” Update If the URL contains other parameters that may include r in end, the regex can be made stricter: a = [] “http://test.com?r1=2&r12=1&r122=1&r1=1&r124=1&ar1=2&tr2=3&xy4=5”.scan(/(&|\?)(r+\d+=\d+)/) {|x,y| a << … Read more
To return a value from a loop, use break value: def my_def(port) @hsh.each do |k, v| break k if v == port end end In general, @Stefan’s comment solves this particular problem better: def my_def port @hsh.key port end solved return value from loop
The reserved Ruby key word yield is for processing closures (like a Proc or lamda). That said it is some kind of placeholder for processing some logic. In Ruby on Rails view templating it is used for merging in partials. In the case of a layout file like the application.html.erb it merges in controller response … Read more
I figured out the reason for ArgumentError: uncaught throw “Error in record 314675: undefined method ‘[]’ for nil:NilClass’ was primarily from an incomplete set of input variables that is required by the def init method. Because this was an ArgumentError that was thrown from the function1 method, I was only invested in debugging function1. The … Read more
Which makes absolute sense because that class indeed does not contain that method, but as I’ve been reading should ruby search the classes parents and grandparents for the method? That’s correct, but you didn’t declare any superclasses so the superclass will be Object. Which also doesn’t have an each method. If you want an enumerable … Read more
One example would be errors when they are encountered. e.g. in validation errors[:base] << “Value must be an integer.” solved When should you use an empty array in a web application? [closed]