rsq in scala repl

gistfile1.txt

val data = List((1,2),(2,3),(3,4),(4,5),(5,7))
def line(x:Int) = x+1  // guess based on data
 
def mean(xy:List[(Int,Int)]) = xy.map(a=>a._2).sum/(0.0+xy.size)  // average the y's
def sstot(xy:List[(Int,Int)]) = { val mu = mean(data); xy.map(a=>(a._2-mu)*(a._2-mu)).sum } // total sum of squares  
def sserr(xy:List[(Int,Int)]) = { xy.map(a=>(a._2-line(a._1))*(a._2-line(a._1))).sum }  // sum of squares of residuals
def rsq(xy:List[(Int,Int)]) = 1.0 - sserr(xy)/sstot(xy) 
 
scala> rsq(data)
res5: Double = 0.9324324324324325  // 93% fit, not bad for a guess.