R/calc_Stats.R

In tzerk/roughness: A Collection of Functions Related to Soil Surface Roughness

#' Calculate basic statistics
#' 
#' This function calculates several descriptive statistics.
#' 
#' @param data \code{\link{data.frame}} (\bold{required}): 
#' A log file imported with \code{\link{import_Data}}.
#'
#' @return A \code{\link{data.frame}} with information on the mean, median,
#' standard deviation, relative standard deviation, variance, range,
#' minimum and maximum value and slope of a linear regression.
#' 
#' @export
#'
#' @examples
#' # none
calc_Stats <- function(data) {
  
  # only take the x and y values of the data set
  df <- data[ ,1:2]
  colnames(df) <- c("x", "y")
  
  # only y values
  y <- na.omit(df[ ,2])
  
  # standard statistical parameters
  mean <- mean(y)
  median <- median(y)
  sd <- sd(y)
  rsd <- sd / mean * 100
  var <- sd^2
  range <- max(y) - min(y)
  min <- min(y)
  max <- max(y)
  
  # linear regression
  lm <- lm(y ~ x, data = df)
  slope <- abs(coef(lm)[2])
  
  # create results object
  res <- data.frame(mean = mean,
                    median = median,
                    sd = sd,
                    rsd = rsd,
                    var = var,
                    range = range,
                    min = min,
                    max = max,
                    slope = slope)
  
  return(res)
}