R/nlCor.R

In pratikpitreds/nlCor: Non Linear Correaltion - Quantify the Non linear correlations among variables

#' Non Linear Correaltion (Matrices)- Correlation coeffecient by considering non linear realtionships among two or more variables
#' @param x         a numeric vector, matrix or data frame.
#' @param y         a vector, matrix or data frame with compatible dimensions to x
#' @param inverse   an optional parameter to take the relation between inverse eg. checking 1/x^2,1/x^3 insted of x^2, x^3
#' @param n         Maximum Order of relation you would want to check
#' @param method    a character string indicating which correlation coefficient (or covariance) is to be computed.
#' @param method    log(logarithmic), poly(Polynomial), expo(Exponential), Linear. Default is log.

#' @examples x <- mtcars[,1:2]
#' @examples y <- mtcars[,1:2]
#' @examples nlCor(x,y,method="poly",n=3)
#' @return Returns Non Linear Correlation coeffecient
#' @export

nlCor <-function(x,y,inverse=F,n=2,method="log",na.rm=F){
  #checking the error conditions on arguments

  X <- as.matrix(x)
  Y <- as.matrix(y)

  if (!(is.logical(inverse)))
    stop("'Inverse' must be Logical")

  if (!(n%%1==0))
    stop("'n' must be an Integer")

  na.method <- pmatch(method, c("poly", "log", "expo","Linear"))
  for(i in 1:length(na.method)){
    if(is.na(na.method[i]))
      stop("invalid 'method' argument")
  }
  if (!(is.numeric(X) || is.logical(X)))
    stop("'X' must be all numeric")

  if (!(is.numeric(Y) || is.logical(Y)))
    stop("'Y' must be all numeric")


  if("poly" %in% method){
    if(inverse==FALSE){
      for(i in 2:n){
        X2 <- X^i
        print(paste0("Poly Converse of Order ",i," :"))
        print(cor(X2,Y))
      }
    }
    else{
      for(i in 1:n){
        X2 <- X^(-i)
        print(paste0("Poly Inverse of Order ",i," :"))
        print(cor(X2,Y))
      }
    }
  }
  if("expo" %in% method){
    if(inverse==FALSE){
      for(i in 2:n){
        X2 <- i^X
        print(paste0("Expo Converse of Value ",i," :"))
        print(cor(X2,Y))
      }
    }
    else{
      for(i in 2:n){
        X2 <- i^(-X)
        print(paste0("Expo Inverse of Value ",i," :"))
        print(cor(X2,Y))
      }
    }
  }
  if("log" %in% method){
    if(inverse==FALSE){
      X2 <- log(X)
      print(paste0("Logarithmic Correlation :"))
      print(cor(X2,Y))
    }
    else{
      for(i in 2:n){
        X2 <- exp(X)
        print(paste0("Logarithmic Inverse Correlation :"))
        print(cor(X2,Y))
      }
    }
  }
  if("Linear" %in% method){
    print(paste0("Linear Correlation :"))
    print(cor(X,Y))
  }
}