Finding the most occurring character/letter in a string

Question

Trying to get the most occurring letter in a string.

So far:

puts "give me a string"
words = gets.chomp.split
counts = Hash.new(0)
words.each do |word|
  counts[word] += 1
end

Does not run further than asking for a string. What am I doing wrong?

Answer 1

If you're running this in irb, then the computer may think that the ruby code you're typing in is the text to analyse:

irb(main):001:0> puts "give me a string"
give me a string
=> nil
irb(main):002:0> words = gets.chomp.split
counts = Hash.new(0)
words.each do |word|
counts[word] += 1
end=> ["counts", "=", "Hash.new(0)"]
irb(main):003:0> words.each do |word|
irb(main):004:1* counts[word] += 1
irb(main):005:1> end
NameError: undefined local variable or method `counts' for main:Object
    from (irb):4:in `block in irb_binding'
    from (irb):3:in `each'
    from (irb):3
    from /Users/agrimm/.rbenv/versions/2.2.1/bin/irb:11:in `<main>'
irb(main):006:0> 

If you wrap it in a block of some sort, you won't get that confusion:

begin
  puts "give me a string"
  words = gets.chomp.split
  counts = Hash.new(0)
  words.each do |word|
    counts[word] += 1
  end
  counts
end

gives

irb(main):001:0> begin
irb(main):002:1*   puts "give me a string"
irb(main):003:1>   words = gets.chomp.split
irb(main):004:1>   counts = Hash.new(0)
irb(main):005:1>   words.each do |word|
irb(main):006:2*     counts[word] += 1
irb(main):007:2>   end
irb(main):008:1>   counts
irb(main):009:1> end
give me a string
foo bar
=> {"foo"=>1, "bar"=>1}

Then you can work on the fact that split by itself isn't what you want. :)

Answer 2

This should work:

puts "give me a string"
result = gets.chomp.split(//).reduce(Hash.new(0)) { |h, v| h.store(v, h[v] + 1); h }.max_by{|k,v| v}
puts result.to_s

Output:

@Alan ➜  test rvm:(ruby-2.2@europa)  ruby test.rb
give me a string
aa bbb cccc ddddd
["d", 5]

Or in irb:

:008 > 'This is some random string'.split(//).reduce(Hash.new(0)) { |h, v| h.store(v, h[v] + 1); h }.max_by{|k,v| v}
 => ["s", 4]

Answer 3

Rather than getting a count word by word, you can process the whole string immediately.

  str = gets.chomp
  hash = Hash.new(0)
  str.each_char do |c|
    hash[c] += 1 unless c == " " #used to filter the space
  end

After getting the number of letters, you can then find the letter with highest count with

max = hash.values.max

Then match it to the key in the hash and you're done :)

puts hash.select{ |key| hash[key] == max }

Or to simplify the above methods

hash.max_by{ |key,value| value }

The compact form of this is :

  hash = Hash.new(0)
  gets.chomp.each_char { |c| hash[c] += 1 unless c == " " }
  puts hash.max_by{ |key,value| value }

Answer 4

This returns the highest occurring character within a given string:

puts "give me a string"

characters = gets.chomp.split("").reject { |c| c == " " }
counts = Hash.new(0)

characters.each { |character| counts[character] += 1 }

print counts.max_by { |k, v| v }