Statistics usable for data series

example.ex

Stream.repeatedly(&:random.uniform/0) 
 |> Enum.take(10000)
 |> Stats.all
 |> IO.inspect

example_output.ex

#run using `elixirc stats.ex && elixir example.ex`

[len: 10000, avg: 0.5000783694558532,
 range: {2.4128016570301725e-4, 0.9999365376549191}, stdev: 0.29015552976626224,
 uniq: 10000,
 pct: [{99, 0.9892887006250969}, {98, 0.9803346036167921},
  {95, 0.9518418120922166}, {90, 0.9028639280861167}, {80, 0.8028527301428907},
  {60, 0.6020177938775699}, {50, 0.4995763856900868}]]

stats.ex

defmodule Stats do
  def all(data) do
    len = length(data)
    avg = sum(data)/len
    [len: len,
     avg: avg,
     range: {Enum.min(data),Enum.max(data)},
     stdev: stdev(data,len,avg),
     uniq: length(Enum.uniq(data)),
     pct: percentiles(data, len)
    ]
  end
  
  def stdev(data,len,avg) do
    total = data 
      |> Enum.map(&(&1-avg))
      |> Enum.map(&(&1*&1))
      |> sum() 
    :math.sqrt(total / len)
  end
  
  def sum(data) do
    Enum.reduce(data,0,&(&1+&2))
  end
	
  def percentiles(data, len) do
	sorted = Enum.sort(data)
	[99,98,95,90,80,60,50] 
	   |> Enum.map( &({&1,Enum.at(sorted,round(&1*len/100))}))
  end
end