TECH603 Day 2 - Working with country data and Hashes

country_hashes.rb

# Convert all of the following country data in to a Hash, like that of Angola

# Angola
angola = {
  "id" => "AGO",
  "name" => "Angola",
  "population" => 21_471_618,
  "capital" => "Luanda",
  "latitude" => -8.81155,
  "longitude" => 13.242,
  "income_level" => "Upper Middle",
  "high_income" => false
}

# Antigua and Barbuda
# id: "ATG"
# name: "Antigua and Barbuda"
# population: 89_985
# capital: "Saint John's"
# latitude: 17.1175
# longitude: -61.8456
# income_level: "High"
# high_income: true
antigua_and_barbuda = {
  "id" => "ATG",
  "name" => "Antigua and Barbuda",
  "population" => 89_985,
  "capital" => "Saint John's",
  "latitude" => 17.1175,
  "longitude" => -61.8456,
  "income_level" => "High",
  "high_income" => true
}


# Belarus
# id: "BLR"
# name: "Belarus"
# population: 9_466_000
# capital: "Minsk"
# latitude: 53.9678
# longitude: 27.5766
# income_level: "Upper Middle"
# high_income: false
belarus = {
  "id" => "BLR",
  "name" => "Belarus",
  "population" => 9_466_000,
  "capital" => "Minsk",
  "latitude" => 53.9678,
  "longitude" => 27.5766,
  "income_level" => "Upper Middle",
  "high_income" => false
}

# Central African Republic
# id: "CAF"
# name: "Central African Republic"
# population: 4_616_417
# capital: "Bangui"
# latitude: 5.63056
# longitude: 21.6407
# income_level: "Low"
# high_income: false
central_african_republic = {
  "id" => "CAF",
  "name" => "Central African Republic",
  "population" => 4_616_417,
  "capital" => "Bangui",
  "latitude" => 5.63056,
  "longitude" => 21.6407,
  "income_level" => "Low",
  "high_income" => false
}


# Switzerland
# id: "CHE"
# name: "Switzerland"
# population: 8_081_482
# capital: "Bern"
# latitude: 46.948
# longitude: 7.44821
# income_level: "High"
# high_income: true
switzerland = {
  "id" => "CHE",
  "name" => "Switzerland",
  "population" => 8_081_482,
  "capital" => "Bern",
  "latitude" => 46.948,
  "longitude" => 7.44821,
  "income_level" => "High",
  "high_income" => true
}


# Output Angola
puts angola

# Output each key/value pair for Angola
angola.each_pair { |key, value| puts "#{key},#{value}" }

# Output each key/value pair for Switzerland
switzerland.each_pair{|k,v|puts"#{k},#{v}"}

# Output each key/value pair for Belarus
belarus.each_pair do |key, value|
  puts "#{key},#{value}"
end

# a list of countries
countries = [
  angola,
  switzerland,
  belarus,
  antigua_and_barbuda,
  central_african_republic
]

# loop through each country in the list
countries.each_with_index do |country, index|
  puts "#{country["name"]} at index #{index}"
  puts "---"

  # for each country (Hash), loop through each key and value
  country.each_pair do |key, value|
    puts "#{key},#{value}"
  end
end

puts "---"
puts "CSV"
puts "---"

# Super neat CSV / Spreadsheet example!!!
headers = countries.first.keys
puts %("#{headers.join("\",\"")}")

countries.each do |country|
  puts %("#{country.values.join("\",\"")}")
end


headers = countries.first.keys.map { |key| %("#{key}") }.join(",")
puts headers

countries.each do |country|
  values = country.values.map do |value|
    %("#{value}")
  end
  puts values.join(",")
end

country_variables.rb

# DRY this up!
# DRY - Don't Repeat Yourself! :)

# Data Type vs. Data Structure
# 
# New Data Type: Hash (or dictionary)
# A Hash is a Data Structure


# Angola:
country0_id = "AGO"
country0_name = "Angola"
country0_population = 21_471_618
country0_capital = "Luanda"
country0_latitude = -8.81155
country0_longitude = 13.242
country0_income_level = "Upper Middle"
country0_high_income = false

country0 = {
  "id"           => "AGO",
  "name"         => "Angola",
  "population"   => 21_471_618,
  "capital"      => "Luanda",
  "latitude"     => -8.81155,
  "longitude"    => 13.242,
  "income_level" => "Upper Middle",
  "high_income"  => false
}

puts country0["name"]
puts country0["population"]
puts country0

# ask for a non-existent key
puts country0["foo"].inspect

# insert something new in to the dictionary
country0["foo"] = "bar"

# the value now exists
puts country0
puts country0["foo"]

# check out the keys, then the values
puts country0.keys.to_s
puts country0.values.to_s

puts country0.keys.count
puts country0.keys.length
puts country0.keys.size

puts country0.values.count
puts country0.values.length
puts country0.values.size

puts country0.keys.sort

# Antigua and Barbuda:
country1_id = "ATG"
country1_name = "Antigua and Barbuda"
country1_population = 89_985
country1_capital = "Saint John's"
country1_latitude = 17.1175
country1_longitude = -61.8456
country1_income_level = "High"
country1_high_income = true

country1 = {
  "id" => "ATG",
  "name" => "Antigua and Barbuda",
  "population" => 89_985,
  "capital" => "Saint John's",
  "latitude" => 17.1175,
  "longitude" => -61.8456,
  "income_level" => "High",
  "high_income" => true
}

puts country1["longitude"]
puts country1["latitude"]
puts country1.key?("foo")

unless country1.key?("bar")
  puts "I can't find the key 'bar'"
end

puts "I can't find the key 'bar'" if !country1.key?("bar")

country1["baz"] = nil # or nil
unless country1["baz"]
  puts "The value of 'bar' is falsey"
end

# Belarus:
country2_id = "BLR"
country2_name = "Belarus"
country2_population = 9_466_000
country2_capital = "Minsk"
country2_latitude = 53.9678
country2_longitude = 27.5766
country2_income_level = "Upper Middle"
country2_high_income = false

# Central African Republic:
country3_id = "CAF"
country3_name = "Central African Republic"
country3_population = 4_616_417
country3_capital = "Bangui"
country3_latitude = 5.63056
country3_longitude = 21.6407
country3_income_level = "Low"
country3_high_income = false

# Switzerland:
country4_id = "CHE"
country4_name = "Switzerland"
country4_population = 8_081_482
country4_capital = "Bern"
country4_latitude = 46.948
country4_longitude = 7.44821
country4_income_level = "High"
country4_high_income = true

# is country4 population greater than country 1
puts country4_population > country1_population

# output all of the country ids
puts country0_id, country1_id, country2_id, country3_id, country4_id