Histrogram

import IEx.Helpers

Build a histogram with library function

Example

istogram.build("apple")

a | *
p | **
l | *
e | *

"let us get started on some elixir"
|> String.graphemes()
|> Enum.frequencies()
|> Enum.map(fn {key, value} ->
  "#{key} | #{String.duplicate(~s[*], value)}"
end)
|> Enum.join("\n")
|> IO.puts

Histogram with Enum.map/1

"build a histogram with the map function"
|> String.graphemes()
|> Enum.group_by(&(&1))
|> Enum.map(fn {k, v} -> {k, length(v)} end)
|> Enum.sort()
|> Enum.map(fn {key, count} ->
  "#{key} | #{String.duplicate(~s[*], count)}"
end)
|> Enum.join("\n")
|> IO.puts

h Enum.sort/1

Histogram with Enum.reduce/3

# add one letter to the frequency map

acc = %{"a" => 1, "p" => 1}
letter = "l"

# Map.put(acc, letter, acc[letter] + 1) # broken because of non-exixtant values
add_one_letter = 
  fn letter, acc -> 
    Map.update(acc, letter, 1, fn x -> x + 1 end) 
  end

# "build a histogram with the reduce function"
# |> Enum.reduce(%{}, fn letter, acc ->
#   Map.update(acc, letter, 1, &(&1 + 1))
# end)

# acc[letter] + 1

# "build a histogram with the reduce function"
# |> String.graphemes()

print_one_row =
  fn {letter, count}, acc ->
    stars = String.duplicate("*", count)
    row = "#{letter} | #{stars}"
    IO.puts(row)
    [row | acc]
  end

print_one_row.({"p", 2}, [])

"build a histogram with the map function"
|> String.graphemes()
|> Enum.reduce(%{}, add_one_letter))
|> Enum.sort()
|> Enum.reduce([], print_one_row)

&(&1 + 1)