aarti

irb(main):001:0> h = { a: 1, b: 2 }
=> {:a=>1, :b=>2}
# each_with_object same as reduce or inject, memo is a new hash.
# unpack arguments in block
irb(main):002:0> h.each_with_object({}) {|(k,v),new_hash| new_hash[v] =k }
=> {1=>:a, 2=>:b}

aarti

a =[{n: 1}, {n: 5}, {n: 3}]
a.sort {|x,y| x[:n]<=>y[:n] } #=> [{:n=>1}, {:n=>3}, {:n=>5}]
a.sort_by{|x| x[:n].to_i } #=> [{:n=>1}, {:n=>3}, {:n=>5}]

aarti

→ git remote prune origin
→ git branch --merged | grep -v "\*" | xargs -n 1 git branch -d

# Remember to do this from the master branch
# If you run it from a feature branch the master branch gets deleted.
→ git branch --merged | grep -v "\*" | xargs -n 1 git branch -d
Deleted branch master (was 644eb76).

You can recheckout master branch
→ git checkout -b master origin/master

aarti

irb(main):040:0> testcases
=> ["hello world", "'hello world", "'hello' world", "hello' world"]
irb(main):041:0> testcases.each { |i| puts /(?<!')hello(?!')/.match(i) }
hello



=> ["hello world", "'hello world", "'hello' world", "hello' world"]

aarti

audience_range_values = []
age_from = nil
audience_range_values << age_from || 3 # does not work, returns book.a

print audience_range_values

audience_range_values = []

# output [nil]

aarti

Many concepts here to revisit, so saving in gist.
http://stackoverflow.com/questions/21712814/how-can-i-extract-the-bigger-value-for-each-key-in-a-list-of-hashes-in-ruby/21729254?noredirect=1#comment32860522_21729254

a = [{1=>19.4}, {1=>12.4}, {2=>29.4}, {3=>12.4}, {2=>39.4}, {2=>59.4}]

# the below is the main trick, to group the hashes and sorted the key/value pair
# in **ascending order**.
a.sort_by(&:to_a)
# => [{1=>12.4}, {1=>19.4}, {2=>29.4}, {2=>39.4}, {2=>59.4}, {3=>12.4}]

aarti

irb(main):001:0> 'A' * 3
=> "AAA"

aarti

# I thought this was neat
# Reference: http://stackoverflow.com/questions/21404323/combining-two-different-ranges-to-one-in-ruby

[*'0'..'9', *'a'..'z', *'A'..'Z'].shuffle.first(2).join

aarti

function genericallyCallingMap(dna) {
  var complements = {"C":"G", "G":"C", "T":"A", "A":"U"};  
  var map = Array.prototype.map
  var a = map.call(dna, function(x) {
     return complements[x];
   })
  return a.join("");
};
function callingMapOnAnArray(dna) {
  var a = dna.split("").map( function(x) {

aarti

class Bst
  
  attr_accessor :data, :left, :right
  
  def initialize(data)
    self.data = data
  end
  
  def insert_r(data)
    if (self.right )