Data_Extrapolate_Function.R

##Data_Extrapolation_Function##
#This function will take dataframes that contain measured soil variables and make a smooth curve of each variable vs. soil depth
#The function will use the smoothed curve to extrapolate a soil response variable value for every centimeter in the soil profile
#The function will store each vector of responses and merge those vectors into a single dataframe after it extrapolates all the resonse variable sets
#The function will return a single dataframe with all the response variables. 
#***DAN: this is a pretty good description above, but...

#Args:
  #soilDatSet: This is a dataframe from which the user is extrapolating datapoints via linear interpolation
  #datReturn: gives user the option to return and view the complete data vector. If datReturn = F, the function only returns a data plot.
  #... : allows the user to specify arguments for plot parameters, such as axis labels and colors. 
#***DAN: ... these specs should be more precise. What is the assumed format of soilDatSet?

#Initial pseudocode:
#Data_Fill <- function(soilDatSets=SoilDatList)
#{
  #soilDat <- Make and empty dataframe into which columns of data may be added
  #for(set in soilDatSets)
  #{
    #plot(responseVar ~ soil depth)
    #make as smooth curve over the points
    #extrapolate a value at each 1 cm depth up to 2m
    #put values in a vector
    #soilDat[set] <- new vector becomes a dataframe column
  #}
  #return(soilDat)
#}
#***DAN: I am glad you are writing pseudocode


#Function that produces a plot and a set of response variable points generated using linear interpolation between sampled datapoints, as well as a plot of extrapolated and measured points.
data_fill <- function (soilDatSet, datReturn, ...)
{
  x <-soilDatSet[,2]
  y <- soilDatSet[,1]
df1 <- data.frame(x,y)
dfOrdered <- df1
plot(x=dfOrdered$x,y=dfOrdered$y,col="red", pch = 19, ylab = "Soil Depth (cm)", xlab = ..., ylim = c(180,0))
demo <- (approx(y=dfOrdered$x, x=dfOrdered$y, xout=seq(4,175)))
points(demo$x~demo$y, pch = 1, cex = 0.5, ylim = c(180,0))
  if(datReturn == T)
    {
      return(demo$y)
    }
}


#Then Produce a dataframe with each extrapolated response variable
#This could be more modular. I need to make my dataframes into a vector. However, I'm having trouble getting my function to run when I do this.
#To make a vector, I think I should do this:
# soilDataSets <- as.vector(PiFra, PoFra, EOC.c, AP.cs, AP.EO)
  
#SoilSummDat <- as.data.frame(4:175)
#colnames(SoilSummDat) <- "Depth"
#SoilSummDat$Pi <- data_fill(PiFra)
#SoilSummDat$Po <- data_fill(PoFra)
#SoilSummDat$EOC <- data_fill(EOC.c)
#SoilSummDat$AP <- data_fill(AP.cs)
#SoilSummDat$APEOC <- data_fill(AP.EO)
#SoilSummDat