How To Compute Commodity Channel Index (CCI) using Erlang?

@leonor 

Commodity Channel Index (CCI) measures the deviation of a financial instrument's price from its average price. It is typically calculated using the following formula:

CCI = (Price - SMA) / (0.015 * Mean Deviation)

Where:

• Price is the current closing price of the asset
• SMA is the simple moving average of the asset's closing prices over a specified period
• Mean Deviation is the mean deviation of the asset's closing prices from its SMA over the specified period

To compute CCI using Erlang, you can use the following code snippet:

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-module(cci).
-export([compute_cci/2]).

compute_cci(Prices, Period) ->
    Averages = moving_average(Prices, Period),
    Deviations = [abs(X - lists:nth(Index, Averages)) || {X, Index} <- lists:zip(Prices, lists:seq(1, length(Prices)))],
    MeanDeviation = lists:sum(Deviations) / length(Deviations),
    {Price, _} = lists:last(Prices),
    SMA = lists:last(Averages),
    CCI = (Price - SMA) / (0.015 * MeanDeviation),
    CCI.


moving_average(Prices, Period) ->
    lists:map(fun(X) -> average(lists:sublist(Prices, X-Period, Period)) end, lists:seq(Period, length(Prices))).

average(List) when length(List) > 0 ->
    lists:sum(List) / length(List);
average(_) ->
    0.

In this code snippet, the compute_cci/2 function takes a list of prices and a period as input and computes the CCI value. It first calculates the moving averages of the prices using the moving_average function, then computes the mean deviation and finally calculates the CCI value using the formula mentioned above.

You can call the compute_cci/2 function with a list of prices and a specified period to get the CCI value for that particular asset.