generalAxis.R

#' Axis generation for log discharge
#'
#' Discharge axis tick generation
#'
#' @param x vector to create scale about
#' @param maxVal number maximum value on returned scale
#' @param minVal number minimum value on returned scale
#' @param logScale logical whether or not to return a log scale
#' @param tinyPlot logical
#' @param padPercent number used to pad the max and min if not specified
#' @param concentration logical if concentration=TRUE, labels returned as concentration units, otherwise flux units.
#' @param units character concentration units. Typically found in INFO$param.units.
#' @param usgsStyle logical option to use USGS style guidelines. Setting this option
#' to TRUE does NOT guarantee USGS compliance. It will only change automatically
#' generated labels
#' @param prettyDate logical use 'pretty' limits for date axis if TRUE, or force the yearStart/yearEnd as limits if FALSE
#' @keywords graphics water-quality statistics
#' @param concLab object of concUnit class, or numeric represented the short code, 
#' or character representing the descriptive name. By default, this argument sets
#' concentration labels to use either Concentration or Conc (for tiny plots). Units
#' are taken from the eList$INFO$param.units. To use any other words than
#' "Concentration" see \code{vignette(topic = "units", package = "EGRET")}.
#' @export
#' @examples
#' eList <- Choptank_eList
#' Daily <- getDaily(eList)
#' INFO <- getInfo(eList)
#' x <- Daily$Q
#' max <- max(x)
#' min <- 0
#' units <- INFO$param.units
#' generalAxis(x, max, min, units)
#' min <- min(x)
#' generalAxis(x, max, min, units, log=TRUE)
#' generalAxis(Daily$ConcDay, 100, 0, concLab = "concentration")
generalAxis <- function(x,
                        maxVal,
                        minVal,
                        units = NA,
                        logScale = FALSE,
                        tinyPlot = FALSE,
                        padPercent = 5,
                        concentration = TRUE,
                        concLab = 1,
                        usgsStyle = FALSE,
                        prettyDate = TRUE) {
  
  
  nTicks<-if(tinyPlot) 5 else 8
  
  upperMagnification <- 1 + (padPercent / 100)
  lowerMagnification <- 1 - (padPercent / 100)
  
  if (max(x,na.rm=TRUE) > 0){
    high <- if(is.na(maxVal)) {upperMagnification*max(x,na.rm=TRUE)} else {maxVal}
  } else {
    high <- if(is.na(maxVal)) {lowerMagnification*max(x,na.rm=TRUE)} else {maxVal}
  }
  
  if (min(x,na.rm=TRUE) > 0){
    low <- if(is.na(minVal)) {lowerMagnification*min(x,na.rm=TRUE)} else {minVal}
  } else {
    low <- if(is.na(minVal)) {upperMagnification*min(x,na.rm=TRUE)} else {minVal}
  }
   
  if(concentration){
    
    if (is.numeric(concLab)){
      concPrefix <- concConst[shortCode=concLab][[1]]    
    } else if (is.character(concLab)){
      concPrefix <- concConst[concLab][[1]]
    } else {
      concPrefix <- concLab
    }
    
    if (tinyPlot){
      label <- paste0(concPrefix@shortPrefix, ". (",units,")")
    } else {
      if(usgsStyle){
        localUnits <- toupper(units) 
        possibleGoodUnits <- c("mg/l","mg/l as N", "mg/l as NO2", 
                               "mg/l as NO3","mg/l as P","mg/l as PO3","mg/l as PO4","mg/l as CaCO3",
                               "mg/l as Na","mg/l as H","mg/l as S","mg/l NH4" )
        
        allCaps <- toupper(possibleGoodUnits)
        
        if(localUnits %in% allCaps){
          label <- "Concentration, in milligrams per liter"
        } else {
          label <- paste0(concPrefix@longPrefix, ", in ",units)
        }
        
      } else {
        label <- paste0(concPrefix@longPrefix, " in ", units)
      }
    }
  } else {
    label <- ""
  }
  
  span <- c(low, high)
  
  ticks <- if (logScale) {
    if (tinyPlot) {
      logPretty1(low, high)
    } else {
      logPretty3(low, high)
    }
  } else {
    pretty(span, n = nTicks)
  }
  
  numTicks <- length(ticks)
  bottom <- ticks[1]
  top <- ticks[numTicks]
  
  if(!prettyDate){
    bottom <- minVal
    top <- maxVal
    ticks[1] <- minVal
    ticks[length(ticks)] <- maxVal
  }
  
  return(list(ticks=ticks, bottom=bottom, top=top, label=label))
}