How To Compute Relative Strength Index (RSI) using Scala?

@genevieve_boehm 

To compute the Relative Strength Index (RSI) using Scala, you can follow these steps:

1. Define the period for which you want to calculate RSI (usually 14 days is used).
2. Create a list of historical closing prices for the given period.
3. Calculate the daily price changes by subtracting the current day's closing price from the previous day's closing price.
4. Separate the positive and negative daily price changes into their respective lists.
5. Calculate the average gain (AG) and average loss (AL) over the defined period.
6. Calculate the Relative Strength (RS) by dividing the AG by AL.
7. Calculate the RSI using the formula: RSI = 100 - (100 / (1 + RS)).

Here is an example of how you can implement this in Scala:

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def calculateRSI(prices: List[Double], period: Int): Double = {
  val priceChanges = prices.sliding(2).map{ case List(a, b) => b - a }.toList
  val (positiveChanges, negativeChanges) = priceChanges.partition(_ > 0)
  
  val averageGain = positiveChanges.take(period).sum / period
  val averageLoss = negativeChanges.take(period).map(Math.abs).sum / period
  
  val RS = if (averageLoss != 0) averageGain / averageLoss else 0
  val RSI = 100 - (100 / (1 + RS))

  RSI
}

// Example usage
val prices = List(10.2, 12.5, 11.8, 14.6, 16.3, 15.7, 17.2, 19.8, 21.5, 22.3, 20.9, 19.5, 18.7, 23.2)
val period = 14

val rsi = calculateRSI(prices, period)
println(s"The RSI for the given prices is: $rsi")

This code snippet demonstrates how to calculate RSI for a list of historical prices over a specified period using Scala.