malandrina

Implementing a Reverse Polish notation calculator in Ruby

A couple weeks ago I had a go at implementing an RPN calculator in Ruby. I knew I wanted the calculator to function by popping operands out of an array populated with the values of the input expression, operating upon the operands with the appropriate operator, and pushing the result back into the stack of operands.

I was able to implement this in version 1, but it took forever and the resulting code was not very beautiful. Why?

• I started coding before I had a thorough understanding of RPN

  Wait, 20 10 5 4 + * - is what now?

malandrina

Anagram solvers for same-length, single word anagrams, in Ruby

I wanted to write an anagram solver that would return a list of the anagrams of the same length of a given word/combination of characters, such that:

same_length_anagrams("deify") => "edify"

or

same_length_anagrams("ogb") => "bog", "gob"

malandrina

Writing a faster anagram solver for same-length, one-word anagrams, in Ruby

In [my first attempt] (https://gist.github.com/3745321) at writing an anagram solver, I stored my word list in a hash in which values are words and keys are characters in those words, sorted alphabetically.

I liked this approach, but my implementation was not ideal: I defined the creation of the hash as an activity that occurs when the #same_length_anagrams method is called. This, of course, made it super slow!

This time I was able to structure things so that the word list hash is created when the program is initialized. The Ruby documentation for the #shell class leaves a lot to be desired, but [this very helpful blog post] (http://devver.wordpress.com/2009/10/12/ruby-subprocesses-part_3/) on starting sub-processes in Ruby provided me with a great point of departure. My next step is to figure out how to clean up lines 1 - 12.

# Create word list hash

malandrina

class FileReader
  def initialize(file)
    @file = file
  end

  def read_file
    @dictionary = {}
    File.open(@file, "r").each do |line|
      line.gsub!(/\\/, "")
      split_line = line.chomp.split("\t")

malandrina

def filter_by_highest_ranked_user_coaches
  coach_user_ids_string = coach_user_ids.to_s.gsub('[', '').gsub(']', '')

  highest_ranked_coach_ids = ActiveRecord::Base.connection.execute(<<-TEXT
    SELECT DISTINCT on (user_id) user_id, id
    FROM coaches c
    WHERE coachup_ranking_score =
      (SELECT MAX(r.coachup_ranking_score)
        FROM coaches r
        WHERE c.user_id = r.user_id

malandrina

class Geocoder
  queryGeocodingApi: (options) ->
    if options.coordinates
      formattedLatlng = "#{options.coordinates.latitude},#{options.coordinates.longitude}"
      @.reverseGeocode(latlng: formattedLatlng)
 
  reverseGeocode: (options) ->
    $.ajax
      type: 'GET'
      url: 'https://maps.googleapis.com/maps/api/geocode/json'

malandrina

module GeospatialObject
  METERS_PER_MILE = 1609.34
  
  module Callbacks
    def set_geographic_point
      ActiveRecord::Base.connection.execute(<<-TEXT
        UPDATE addresses
        SET geographic_point = ST_GeographyFromText('POINT(' || longitude || ' ' || latitude || ')')
        WHERE id = #{self.id}
      TEXT

malandrina

DEPRECATION WARNING: It looks like you are eager loading table(s) (one of: agents, hoteltonight) that are referenced in a string SQL snippet. For example:

    Post.includes(:comments).where("comments.title = 'foo'")

Currently, Active Record recognizes the table in the string, and knows to JOIN the comments table to the query, rather than loading comments in a separate query. However, doing this without writing a full-blown SQL parser is inherently flawed. Since we don't want to write an SQL parser, we are removing this functionality. From now on, you must explicitly tell Active Record when you are referencing a table from a string:

    Post.includes(:comments).where("comments.title = 'foo'").references(:comments)

If you don't rely on implicit join references you can disable the feature entirely by setting `config.active_record.disable_implicit_join_references = true`. (called from _app_views_agents_index_html_haml__860689087346826956_70228045189400 at /Users/training/Source/thoughtbot/hotelstonight/app/vi

malandrina

{
  "mapStyles": {
     "destinationHighlight":{
      "useClientId":true,
      "ease":"Back.easeInOut.config(1.7)",
      "fill":"#FFFFFF"
    },
    "categoryHighlight":{
      "ease":"Back.easeInOut.config(1.7)",
      "fills":{

malandrina

{
  "mapStyles": {
     "destinationHighlight":{
      "useClientId":true,
      "ease":"Back.easeInOut.config(1.7)",
      "fill":"#looool"
    },
    "categoryHighlight":{
      "ease":"Back.easeInOut.config(1.7)",
      "fills":{