ReorderingFactorForFacetGridPlot

## reordering a factor for a facet grid plot
# ie when you have a plot with 5 'subplots' within it
# eg for different sample days
# and you want them to be ordered a specific way

# some kind person wrote a function setFactorOrder
# so run this in R to make the functionfirst. 



setFactorOrder <- function(x, order=sort(levels(x))) { 
  # Returns a factor ordered by `order`.  
  # If order is missing, defaults to `levels(x)` if available, else to `sort(unique(x))`
  # Useful for ggplot and elsewhere were ordering is based on the order of the levels
  
  if (!is.factor(x)) {
    warning("`x` is not a factor. Will coerce.")
    levs <- sort(unique(x))
    if (missing(order))
      order <- levs
  } else {
    levs <- levels(x)
  }
  
  # any values in order, not in levels(x)
  NotInx <- setdiff(order, levs)
  
  if (length(NotInx)) {
    warning ("Some values not in x:\n", paste(NotInx, collapse=", "))
  }
  
  # levels(x) not explicitly named in order
  Remaining <-  setdiff(levs, order)
  
  order <- c(setdiff(order, NotInx), Remaining)
  
  factor(x, level=order)
}


## now you can alter your factor
## where PsD is my dataframe and SamplingTime is one of the variables
# ie columns, and I want to specify how to order my 'subplots'
# based on samplingtime info
# inside the c("") put the variables of SamplingTime how 
# you want them ordered in your plot. 

PsD[["SamplingTime"]] <- setFactorOrder(PsD[["SamplingTime"]], c("T0", "T2", "T3", "T7", "T8", "T11", "T13"))

# then you'd go ahead and plot as normal:
# with ggplot

k <- ggplot(PsD, aes(x=SamplingTime,y=Abundance, color = Treatment)) +
  geom_boxplot()


# from from 
# https://stackoverflow.com/questions/19384304/is-there-a-way-to-order-the-ggplot2-facet-grid-subplots