pasture_embed19.rmd

---
runtime: shiny
output: html_document

---

<!-- Simon Woodward, DairyNZ, 2018 -->
<!-- now use joined.rds data, including elevation nitrogen etc -->
<!-- # Note: Unlike Shiny Apps, Interactive R Markdown Documents are do not require ui and server,  -->
<!-- #       the whole document is treated as a server. -->
<!-- # You can't guarantee what order the reactive elements will execute I think -->


```{r setup, include=FALSE} 
knitr::opts_chunk$set(echo = TRUE)

# https://shiny.rstudio.com/articles/shinyapps.html
# note: shiny attempts to upload only packages which are actually used

library(rlang)
library(tidyverse)
library(leaflet) # interactive map (need devtools version of leaflet)
library(ggmap) # register google api
# library(cowplot) # plot box
library(geosphere) # distm
library(proj4) # warning masked by rgdal
library(KernSmooth) # for contouring
library(sp) # spatial polygons
library(quantreg) # quantile regression
library(ggthemes) # chart theme
library(dismo) # geocode
library(raster) # required by geocode. Warning - masks dplyr::select
library(XML) # needed by geocode
library(googleway) # for geocoding

# https://stackoverflow.com/questions/36175529/getting-over-query-limit-after-one-request-with-geocode
# https://developers.google.com/maps/documentation/geocoding/get-api-key
# https://lucidmanager.org/geocoding-with-ggmap/
googlekey <- readLines("google.api") # text file with the API key
# ggmap::register_google(key = googlekey)
# ggmap::ggmap_credentials()

#### these objects are available to all sessions ####
# this is good place to put global data or utility functions
# you can change them (for every session) but you have to use the <<- operator

# read multiyear data and tidy up 
data_all <- readRDS("joined.rds") %>%
  plyr::mutate(pasture_eaten=as.numeric(pasture_and_crop_eaten_t_dm_ha),
         region=as.factor(region),
         season=as.factor(season),
         slope=slope,
         aspect=aspect,
         nitrogen_applied=as.numeric(nitrogen_applied_for_year_l2),
         topo=topo_position_index,
         soil=as.character(nzsc_order)) 
data_all <- data_all %>%
  dplyr::select(farm_number, pasture_eaten, region, season, long, lat, soil, elev, 
         slope, aspect, topo, nitrogen_applied)   
temp <- nrow(data_all)
data_all <- data_all %>% tidyr::drop_na() # drops a lot of rows!
cat(file=stderr(), paste("Rows dropped with missing data =", temp-nrow(data_all), "\n"))
cat(file=stderr(), paste("Rows remaining =", nrow(data_all), "\n"))
# write_tsv(data_all, "data_all.tsv") # dump text version

# add elevation factor
data_all <- data_all %>%
  mutate(elev_fact=factor(x=case_when(elev<=50 ~ "Low (0-50m)", 
                                      elev<=200 ~ "Middle (50-200m)", 
                                     TRUE ~ "High (200m+)"),
                          levels=c("Low (0-50m)", "Middle (50-200m)", "High (200m+)")))

summary(data_all)

# create season and soil list
season_all <- as.list(sort(unique(as.character(data_all$season))))
names(season_all) <- season_all
soil_all <- as.list(sort(unique(data_all$soil)))
names(soil_all) <- soil_all
names(soil_all)[soil_all=="L"] <- "Allophanic"
names(soil_all)[soil_all=="A"] <- "Anthropic"
names(soil_all)[soil_all=="B"] <- "Brown"
names(soil_all)[soil_all=="Z"] <- "Podzol"
names(soil_all)[soil_all=="M"] <- "Pumice"
names(soil_all)[soil_all=="W"] <- "Raw"
names(soil_all)[soil_all=="G"] <- "Gley"
names(soil_all)[soil_all=="N"] <- "Granular"
names(soil_all)[soil_all=="E"] <- "Melanic"
names(soil_all)[soil_all=="R"] <- "Recent"
names(soil_all)[soil_all=="S"] <- "Semiarid"
names(soil_all)[soil_all=="U"] <- "Ultic"
names(soil_all)[soil_all=="O"] <- "Organic"
names(soil_all)[soil_all=="X"] <- "Oxidic"
names(soil_all)[soil_all=="P"] <- "Pallic"
elev_all <- levels(data_all$elev_fact)
names(elev_all) <- elev_all

# define nitrogen steps
nitrogen_range <- seq(0L, 250L, 50L)
nitrogen_here <- as.list(c("Don't Adjust", paste(nitrogen_range, "kgN/ha/y")))
nitrogen_default <- nitrogen_here[[4]]

# calculate nitrogen adjustment
#  could fail if there is insufficient data to do regression
# temp <- data_all %>%
#   group_by(season, elev_fact, soil) %>%
#   do(nitrogen_slope=lm(pasture_eaten ~ nitrogen_applied + 1, data=.)$coefficients["nitrogen_applied"],
#      nitrogen_count=length(.$nitrogen_applied)
#      )
# temp$nitrogen_slope <- unlist(temp$nitrogen_slope)
# ggplot(data=temp) +
#   geom_histogram(mapping=aes(nitrogen_slope*1000)) +
#   scale_x_continuous(limits=c(-30,50))
# temp$nitrogen_count <- unlist(temp$nitrogen_count)
# temp$nitrogen_slope <- median(temp$nitrogen_slope, na.rm=TRUE) # median about 0.010 anyway?
# temp$nitrogen_slope <- 0.010 # after all that, use standard value
data_all <- data_all %>%
  # left_join(temp, by=c("season", "elev_fact", "soil")) %>%
  mutate(
    nitrogen_slope = 0.010,
    pasture_eaten_raw = pasture_eaten,
    pasture_eaten_min = pasture_eaten + (min(nitrogen_range) - nitrogen_applied) * nitrogen_slope,
    pasture_eaten_max = pasture_eaten + (max(nitrogen_range) - nitrogen_applied) * nitrogen_slope
    )

# create data point map/contours for plotting on leaflet
# https://gis.stackexchange.com/questions/168886/r-how-to-build-heatmap-with-the-leaflet-package
data_pts <- unique(data_all[c("long", "lat")])
kde <- KernSmooth::bkde2D(data.matrix(data_pts), bandwidth=c(0.1, 0.1), gridsize=c(100,100))
CL <- contourLines(kde$x1 , kde$x2 , kde$fhat) # contour lines (list)
LEVS <- as.factor(sapply(CL, `[[`, "level")) # contour levels (vector)
NLEV <- length(levels(LEVS)) # number of levels 
pgons <- lapply(1:length(CL), function(i) # convert to polygons (ID=i is actually the level)
    sp::Polygons(list(sp::Polygon(cbind(CL[[i]]$x, CL[[i]]$y))), ID=i))
spgons = sp::SpatialPolygons(pgons)
spgon_cols <- topo.colors(NLEV, NULL)[LEVS]

# convert spatialPolygons to data frame for use in ggplot
#spgonsdf <- broom::tidy(spgons, region=ID)

# calculate NZTM2000 coordinates for farm locations
proj4string <- "+proj=tmerc +lat_0=0.0 +lon_0=173.0 +k=0.9996 +x_0=1600000.0 +y_0=10000000.0 +datum=WGS84 +units=m"
nzgd <- data.matrix(data_all[,c("long", "lat")])
nztm <- proj4::project(xy=nzgd, proj=proj4string)
temp <- proj4::project(xy=nzgd, proj=proj4string, inverse=TRUE)
data_all$east <- nztm[,1]
data_all$north <- nztm[,2]

# define some constants 
trim <- 0.0 # rqss fails near tails if insufficient data
probs <- seq(trim, 1-trim, 0.02) # probabilities for sampcdf
nprobs <- length(probs)
windows <- c(60,40,20)
nmin <- 4L # minimum number of farms in a window for analysis

# gets a list of default ggplot colours
gg_colour_hue <- function(n) {
  hues = seq(15, 375, length = n + 1)
  hcl(h = hues, l = 65, c = 100)[1:n]
}
window_cols <- gg_colour_hue(length(windows))

# default_loc must be somewhere with data!!!
# default_loc <- list(long=172.833333, lat=-41.5) # Nelson
default_loc <- list(long=175.619105, lat=-40.386396) # Massey
# default_loc <- list(long=174.865530, lat=-41.259256) # Wellington
# default_loc <- list(long=175.352116, lat=-37.781841) # DairyNZ
# default_loc <- list(long=167.893066, lat=-43.036775) # In the ocean!

min_long <- 160
max_long <- 180
min_lat <- -50
max_lat <- -30
# default_location <- "Click map or enter location here"
default_location <- ""

# normal list with same elements, useful for testing
my <- list(name="You Are Here",
                     long=default_loc$long,
                     lat=default_loc$lat,
                     distortion=1,
                     east=NA, north=NA,
                     adjust_here=nitrogen_here,
                     adjust_default=nitrogen_default,
                     adjust=nitrogen_default,
                     season_here=list(NA),
                     season=list(NA),
                     soil_here=list(NA),
                     soil=list(NA),
                     elev_here=list(NA),
                     elev=list(NA),
                     data=list(NA),
                     breaks=list(NA),
                     recalc=0L
                     )

```


```{css css_chunk, echo = FALSE}
/* fix cursor */
.leaflet-container {
  cursor: auto !important;
}
/* font doesnt work */
/* https://stackoverflow.com/questions/29274501/r-markdown-changing-font-size-and-font-type-in-html-output/29298407 */
body{
  font-family: Arial;
  font-size: 16pt;
}
/* hHeaders */
h1,h2,h3,h4,h5,h6{
  font-size: 24pt;
}
```


```{r input_pane, echo=FALSE, eval=TRUE}

#### initialise session ####

# useful trigger object to allow manual control (not used yet)
# https://www.r-bloggers.com/dynamically-generated-shiny-ui/
# makeReactiveTrigger <- function() {
#    rv <- reactiveValues(a = 0)
#    list(
#      depend = function() {
#        rv$a
#        invisible()
#      },
#      trigger = function() {
#        rv$a <- isolate(rv$a + 1)
#      }
#    )
# }
# usage
# my_trigger <- makeReactiveTrigger() # create trigger object
# my_trigger$depends() # put this where you want a dependency
# my_trigger$trigger() # put this where you want to trigger the dependency

# collect info about the current location and selections
# these variables are available in the reactive conext
# "my" is not itself a reactive object, it's a list of reactive objects
my <- reactiveValues(name="You Are Here", 
                     long=default_loc$long,
                     lat=default_loc$lat,
                     distortion=1, 
                     east=NA, north=NA, 
                     adjust_here=nitrogen_here,
                     adjust_default=nitrogen_default,
                     adjust=nitrogen_default,
                     season_here=list(NA), 
                     season_default=list(NA), 
                     season=list(NA),
                     soil_here=list(NA), 
                     soil_default=list(NA), 
                     soil=list(NA),
                     elev_here=list(NA), 
                     elev_default=list(NA), 
                     elev=list(NA),
                     data=list(NA),
                     breaks=list(NA),
                     recalc=0L
                     )

# set leaflet info
v <- reactiveValues(zoom=5, minzoom=5, maxzoom=15, long=NA, lat=NA) 

# initialise map centre
isolate({
  cat(file=stderr(), paste("initialise location"), "\n")
  v$long <- my$long
  v$lat <- my$lat
})

#### ui elements ### 

# titlePanel("Where are You?")

output$season_selector <- renderUI({
  cat(file=stderr(), paste("render season selector"), "\n")
  selectInput("season", p("Production season?"), my$season_here, selected=my$season_default)
})

output$elev_selector <- renderUI({
  cat(file=stderr(), paste("render elev selector"), "\n")
  selectInput("elev", p("Altitude over sea level?"), my$elev_here, selected=my$elev_default,
              selectize=FALSE, multiple=TRUE)
})

output$soil_selector <- renderUI({
  cat(file=stderr(), paste("render soil selector"), "\n")
  selectInput("soil", p("Soil orders?"), my$soil_here, selected=my$soil_default, 
              selectize=FALSE, multiple=TRUE)
})

output$nitrogen_checkbox <- renderUI({
  cat(file=stderr(), paste("render adjust checkbox"), "\n")
  selectInput("adjust", p("Nitrogen fertiliser applied?"), my$adjust_here, selected=my$adjust_default)
})

#### make initial map ####

# https://stackoverflow.com/questions/34348737/r-leaflet-how-to-click-on-map-and-add-a-circle
output$map <- renderLeaflet({
  cat(file=stderr(), paste("render leaflet"), "\n")
  
    isolate({ # prevent redraw if arguments change

      leaflet(spgons, options=leafletOptions(minZoom=v$minzoom, maxZoom=v$maxzoom)) %>%
        setView(v$long, v$lat, zoom=v$zoom)  %>%
        addTiles() %>% # default map
        addPolygons(data=spgons, color=spgon_cols, weight=0, options=pathOptions(clickable=FALSE)) %>%
        addMarkers(my$long, my$lat, "layer1", options=pathOptions(clickable=FALSE)) %>%
        addCircles(my$long, my$lat, layerId=as.character(windows), radius=windows*1000, 
                   color=window_cols, weight=4, fill=NA, options=pathOptions(clickable=FALSE))
      
    })

  }) # end renderLeaflet

#### ui layout ####

css <- "
.selectize-input { 
  font-family: Arial;
  font-size: 14px; 
  line-height: 14px;
} 
.selectize-dropdown { 
  font-family: Arial;
  font-size: 14px; 
  line-height: 14px; 
}"

shinyUI(fluidPage(

  tags$style(type='text/css', css),

  sidebarLayout(
    
    sidebarPanel(
      tags$style(".well {background-color:#FFFFFF;border-color:#FFFFFF;}"), # worked!
      cat(file=stderr(), paste("render sidebar"), "\n"),
      width=5, # 12ths of the panel
      uiOutput("season_selector"), 
      uiOutput("elev_selector"),
      uiOutput("soil_selector"), 
      uiOutput("nitrogen_checkbox") 
    ), # end sidebarPanel
    
    mainPanel(
      cat(file=stderr(), paste("render main panel"), "\n"),
      width=7, # 12ths of the panel
      leafletOutput("map", width="100%", height=480), # can manipulate size here
      absolutePanel(top=10, left=70, textInput("search_bar", "" , default_location, "75%")) # search bar
    ), # end mainPanel
    
    position="right"
    
  ) # end sidebarLayout

)) # end fluidPage

#### react to mouse clicks ####

# see also https://rstudio.github.io/leaflet/shiny.html
observeEvent(input$map_click, {
  
  cat(file=stderr(), "\n")
  cat(file=stderr(), paste("observed map_click"), "\n")    

  click <- input$map_click
  my$long <- click$lng
  my$lat <- click$lat
  my$season <- list(NA)
  my$elev <- list(NA)
  my$soil <- list(NA)
  
  # update map
  leafletProxy("map", deferUntilFlush=FALSE) %>%
    addMarkers(my$long, my$lat, "layer1", options=pathOptions(clickable=FALSE)) %>%
    addCircles(my$long, my$lat, layerId=as.character(windows), radius=windows*1000, 
               color=window_cols, weight=4, fill=NA, options=pathOptions(clickable=FALSE)) 
  
}) # end observe mouse click

# https://www.r-bloggers.com/4-tricks-for-working-with-r-leaflet-and-shiny/
observeEvent(input$search_bar, {

  cat(file=stderr(), "\n")
  cat(file=stderr(), paste("observed search bar =", input$search_bar), "\n")
  req(input$search_bar, nchar(input$search_bar)>=4)
  req(googlekey>"")

  # target_pos <- dismo::geocode(paste(input$search_bar, "New Zealand"),
  #                              extent=raster::extent(min_long, max_long, min_lat, max_lat),
  #                              oneRecord=TRUE)
  target_pos <- googleway::google_geocode(paste(input$search_bar, "New Zealand"),
                                          bounds=list(c(min_lat,min_long),c(max_lat,max_long)),
                                          key=googlekey)$results$geometry$location %>% 
    rename(lon=lng)
  cat(file=stderr(), paste(input$search_bar, "=", target_pos$lon, target_pos$lat), "\n")
  req(target_pos$lon, target_pos$lat)
  req(target_pos$lon!="NA", target_pos$lat!="NA")
  req(target_pos$lon>=min_long, target_pos$lon<=max_long)
  req(target_pos$lat>=min_lat, target_pos$lat<=max_lat)
    
  my$long <- target_pos$lon
  my$lat <- target_pos$lat
  my$season <- list(NA)
  my$elev <- list(NA)
  my$soil <- list(NA)

  # update map
  leafletProxy("map", deferUntilFlush=FALSE) %>%
    setView(my$long, my$lat, zoom=input$map_zoom)  %>%
    addMarkers(my$long, my$lat, "layer1", options=pathOptions(clickable=FALSE)) %>%
    addCircles(my$long, my$lat, layerId=as.character(windows), radius=windows*1000,
               color=window_cols, weight=4, fill=NA, options=pathOptions(clickable=FALSE))

}) # end observe search bar
          
#### react to change of location ####

observeEvent(c(my$long, my$lat), {

  cat(file=stderr(), "\n")
  cat(file=stderr(), paste("observed location =", my$long, my$lat), "\n")
    
  # calculate aspect ratio near my farm (not used)
  # nzgd <- data.matrix(tibble(long=c(my$long, my$long, my$long-0.5, my$long+0.5),
  #                            lat=c(my$lat-0.5, my$lat+0.5, my$lat, my$lat)))
  # nztm <- proj4::project(xy=nzgd, proj=proj4string)
  # my$distortion <- (max(nztm[,2])-min(nztm[,2]))/(max(nztm[,1])-min(nztm[,1]))
  
  # location for map centre
  nzgd <- data.matrix(c(my$long, my$lat))
  nztm <- proj4::project(xy=nzgd, proj=proj4string)
  my$east <- nztm[,1]
  my$north <- nztm[,2]

  # calculate distance #
  # we need to use rowwise()  because distm is not vectorised, I think, although rowwise() is deprecated
  # ungroup() removes the effect of rowwise()
  # http://www.expressivecode.org/2014/12/17/mutating-using-functions-in-dplyr/
  data <- data_all %>% 
    rowwise() %>% 
    mutate(dist = geosphere::distm(c(my$long, my$lat), c(long, lat), fun=distHaversine), # this needs rowwise()
           dist = dist/1000) %>%
    ungroup()
  
  # filter data
  temp <- data %>% 
    filter(dist < max(windows)) # km
  
  # insufficient data?
  if (nrow(temp)>=nmin){
    data <- temp
  } else {
    data <- data[1:max(2,nmin-1),] # grab a few rows (they won't be shown)
  }

  # calculate width of histogram for region
  my$breaks <- seq(  floor(min(data$pasture_eaten_raw, data$pasture_eaten_min, data$pasture_eaten_max)), 
                   ceiling(max(data$pasture_eaten_raw, data$pasture_eaten_min, data$pasture_eaten_max)), 
                   1)
  
  # store data for region
  my$data <- data 
 
  # what season are available here   
  i <- sort(unique(as.character(data$season)))
  my$season_here <- season_all[match(i, season_all)]
  n <- unlist(map(my$season_here, function(u) sum(u==data$season)))
  names(my$season_here) <- paste(names(my$season_here), " (", n, " Farms)", sep="")
  cat(file=stderr(), paste("my$season_here =", length(my$season_here)), "\n")
  cat(file=stderr(), paste(names(my$season_here)), "\n")

  # reset selections
  my$season_default <- tail(my$season_here, 1)
  my$season <- my$season_default
  my$elev <- list(NA)
  my$soil <- list(NA)
  # don't change my$adjust
  
}) # end reaction to location changing

#### react to change of season ####

observeEvent(input$season, {
  cat(file=stderr(), "\n")
  cat(file=stderr(), paste("observed input$season =", input$season), "\n")
  req(input$season, input$season!="NA")
  if (my$season != input$season) {
    my$season <- input$season
    my$elev <- list(NA)
    my$soil <- list(NA)
    # don't change my$adjust
  }
})

observeEvent(my$season, {

  cat(file=stderr(), "\n")
  cat(file=stderr(), paste("observed my$season =", my$season), "\n")
  req(my$season, my$season!="NA")

  # make elev list
  data <- my$data %>%
    filter(season == my$season)
  
  # insufficient data?
  if (nrow(data)<nmin){
    data <- my$data[1:max(2,nmin-1),]
  }
  
  # data <- data_all[1:10,] # subset for testing
  i <- unique(data$elev_fact)
  my$elev_here <- elev_all[which(elev_all %in% i)] # retains sorting
  n <- unlist(map(my$elev_here, function(u) sum(u==data$elev_fact)))
  names(my$elev_here) <- paste(my$elev_here, " (", n, " Farms)", sep="")
  cat(file=stderr(), paste("my$elev_here =", length(my$elev_here)), "\n")
  cat(file=stderr(), paste(names(my$elev_here)), "\n")

  # reset selections
  my$elev_default <- my$elev_here
  my$elev <- my$elev_default 
  my$soil <- list(NA)
  # don't change my$adjust
  
}) # end reaction to season changing

#### react to change of elevation ####

observeEvent(input$elev,  {
  cat(file=stderr(), "\n")
  cat(file=stderr(), paste("observed input$elev ="), paste(input$elev), "\n")
  req(input$elev, input$elev!="NA")
  if (any(my$elev != input$elev, na.rm=TRUE)) {
    my$elev <-  input$elev
    my$soil <- list(NA)
    # don't change my$adjust
  }
})

observeEvent(my$elev,  {

  cat(file=stderr(), "\n")
  cat(file=stderr(), paste("observed my$elev ="), paste(my$elev), "\n")
  req(my$elev, my$elev!="NA")

  # make soil list
  data <- my$data %>%
    filter(season == my$season) %>%
    filter(elev_fact %in% my$elev) 
  
  # insufficient data?
  if (nrow(data)<nmin){
    data <- my$data[1:max(2,nmin-1),]
  }

  i <- sort(unique(data$soil))
  my$soil_here <- soil_all[match(i, soil_all)]
  n <- unlist(map(my$soil_here, function(u) sum(u==data$soil)))
  names(my$soil_here) <- paste(names(my$soil_here), " (", n, " Farms)", sep="")
  cat(file=stderr(), paste("my$soil_here =", length(my$soil_here)), "\n")
  cat(file=stderr(), paste(names(my$soil_here)), "\n")

  # reset selections
  my$soil_default <- my$soil_here
  my$soil <- my$soil_default 
  # don't change my$adjust
  
})

#### react to change of soil ####

observeEvent(input$soil, {
  cat(file=stderr(), "\n")
  cat(file=stderr(), paste("observed input$soil ="), paste(input$soil), "\n")
  req(input$soil, input$soil!="NA")
  if (any(my$soil != input$soil, na.rm=TRUE)) {
    my$soil <- input$soil
    # don't change my$adjust
  }
})

observeEvent(my$soil, {
  
  cat(file=stderr(), "\n")
  cat(file=stderr(), paste("observed my$soil = "), paste(my$soil), "\n")
  req(my$soil, my$soil!="NA")
  
  # trigger recalc
  my$recalc <- my$recalc + 1L
  
}) # end reaction to soil changing

#### react to change of adjust ####

observeEvent(input$adjust, {
  cat(file=stderr(), "\n")
  cat(file=stderr(), paste("observed input$adjust =", input$adjust), "\n")
  req(my$adjust, input$adjust)
  if (my$adjust != input$adjust) {
    my$adjust <- input$adjust
  }
})

observeEvent(my$adjust, {
  
  cat(file=stderr(), "\n")
  cat(file=stderr(), paste("observed my$adjust =", my$adjust), "\n")
  req(my$adjust)

  # trigger recalc
  my$recalc <- my$recalc + 1L
  
})

```

<!-- # Your Neighbourhood -->

```{r output_calculations, eval=TRUE, echo=FALSE, warning=TRUE}

#### react to change of inputs ####

calc <- eventReactive(my$recalc,  {

  cat(file=stderr(), "\n")
  cat(file=stderr(), paste("analyse for location =", my$long, my$lat), "\n")
  cat(file=stderr(), paste("analyse for season =", my$season), "\n")
  cat(file=stderr(), paste("analyse for soil ="), paste(my$soil), "\n")
  cat(file=stderr(), paste("analyse for elev ="), paste(my$elev), "\n")
  cat(file=stderr(), paste("analyse for adjust ="), my$adjust, "\n")
  req(my$season!="NA", my$soil!="NA", my$elev!="NA", my$adjust!="NA")
  req(my$long, my$lat, my$season, my$soil, my$elev, my$adjust)

  dont_adjust <- nitrogen_here[[1]]
  nitrogen_level <- as.numeric(word(my$adjust,1))
  data <-  my$data %>% 
    filter(season == my$season) %>% 
    filter(soil %in% my$soil) %>%
    filter(elev_fact %in% my$elev) %>%
    mutate(pasture_eaten = 
             case_when(
               my$adjust==dont_adjust ~ pasture_eaten_raw,
               TRUE ~ pasture_eaten_raw + (nitrogen_level - nitrogen_applied) * nitrogen_slope
               )
           )

  if (my$adjust==dont_adjust){
    my$name <- paste("Your Location (", season_all[my$season[[1]]], ")", sep="")
  } else {
    my$name <- paste("Your Location (", season_all[my$season[[1]]], ")",
                     # " (Nitrogen response = ", sprintf("%.1f", data$nitrogen_slope[1]*1000), ")", 
                     sep="")
  }
  
  cat(file=stderr(), paste("nrow(data) = ", nrow(data)), "\n")

  # circle function
  circle_fun <- function(centre=c(0,0), r=1, npoints=100){
    tt <- seq(0, 2*pi, length.out=npoints)
    xx <- centre[1] + r * cos(tt)
    yy <- centre[2] + r * sin(tt)
    return(tibble(x=xx, y=yy))
  }    
    
  # prepare empty data frames for loop
  farms <- tibble(x=numeric(), y=numeric(), east=numeric(), north=numeric(), long=numeric(), lat=numeric(),
                  pasture=numeric(), dist=numeric(), window=numeric(), radius=factor())
  sampcdf <- tibble(probs=numeric(), quants=numeric(), radius=factor())
  samppdf <- tibble(pasture=numeric(), window=numeric(), radius=factor(),
                    q=numeric(), qr=numeric(), qrlower=numeric(), qrupper=numeric())
  circles <- tibble(east=numeric(), north=numeric(), radius=factor())
  
  # loop through decreasing window sizes 
  for (window in windows) {

    # select data within window
    data_window <- data %>% filter(dist < window)
    n <- nrow(data_window)
    code <- paste(window," km\n(", format(n, width=1), " Farms)", sep="")
    cat(file=stderr(), paste("window = ", window, " km"), "\n")

    # calculate circle
    circle <- circle_fun(centre=c(my$east, my$north), r=window*1000, npoints=100)
    nztm <- data.matrix(circle[,c("x", "y")])
    nzgd <- proj4::project(xy=nztm, proj=proj4string, inverse=TRUE)
    circle$long <- nzgd[,1]
    circle$lat <- nzgd[,2]

    # save selected farms for plot
    if (n >= 1) {
      farms <- rbind(farms, tibble(east=data_window$east, north=data_window$north,
                                 long=data_window$long, lat=data_window$lat,
                                 pasture=data_window$pasture_eaten,
                                 dist=data_window$dist, window=window, radius=as.factor(code)))
    }
    
    circles <- rbind(circles, tibble(long=circle$long, lat=circle$lat, radius=as.factor(code)))

    # save sample quantiles if enough data to be sensible
    if (n >= nmin) {
      
      # calculate quantile
      qr1 <- quantreg::rq(formula=pasture_eaten ~ 1, tau=0.9, data=data_window) # linear quantile regression
      se_method <- "boot" # how condience intervals are calculated, some methods more robust
      yqr1<- predict(qr1, tibble(east=my$east, north=my$north), interval="confidence", level=0.95, se=se_method)
      q90 <- quantile(data_window$pasture_eaten, 0.9, type=1) # also calc simple q90
  
      cat(file=stderr(), paste("yqr1 =", yqr1), "\n")
      # cat(file=stderr(), paste("q90 =", q90), "\n") # should be the same

      quants <- quantile(data_window$pasture_eaten, probs=probs, type=8) # see documentation for type=?
      sampcdf <- rbind(sampcdf, tibble(probs=probs, quants=quants, radius=as.factor(code)))
      samppdf <- rbind(samppdf, tibble(pasture=data_window$pasture_eaten, window=window,
                                       radius=as.factor(code),
                                       q=q90, qr=yqr1[1], qrlower=yqr1[2], qrupper=yqr1[3]))
      
    } # if n >= nmin

    # add a blank line (causes warnings but prevents errors)
    samppdf <- rbind(samppdf, tibble(pasture=NA, window=window,
                                 radius=as.factor(code),
                                 q=NA, qr=NA, qrlower=NA, qrupper=NA))

  } # next window size

  # biggest circle
  circle <- circle_fun(centre=c(my$east, my$north), r=max(windows)*1000, npoints=100)
  nztm <- data.matrix(circle[,c("x", "y")])
  nzgd <- proj4::project(xy=nztm, proj=proj4string, inverse=TRUE)
  circle$long <- nzgd[,1]
  circle$lat <- nzgd[,2]

  # return results as function for testing
  #calc <- function() list(data=data, circles=circles, circle=circle, farms=farms, sampcdf=sampcdf, samppdf=samppdf)
  
  # return results in a list
  return(list(data=data, circles=circles, circle=circle, farms=farms, 
              sampcdf=sampcdf, samppdf=samppdf))
  
}) # end reaction to elev chaning, calculation of calc <- list(results)

```


```{r output_plot, eval=TRUE, echo=FALSE}

#### create histograms ####

output$stacked_histogram <- renderPlot({

  samppdf <- calc()$samppdf # get data for histogram when calc() changes

  isolate({
    
    cat(file=stderr(), paste("render stacked histograms"), "\n")
    
    title_string <- paste("Pasture and Crop Eaten Near", my$name)

    # create empty plot
    stacked_histogram <- ggplot() +
      labs(title=title_string, y="Number of Farms\n", 
           x="Pasture and Crop Eaten, tonnes DM per ha", colour="Radius (km)") +
      # theme_cowplot() +
      #theme_stata(base_size=16, scheme="s2color") +
      # ggthemes::theme_economist_white(base_size=12, horizontal=FALSE) +
      theme(axis.text.x=element_text(size=16, colour="grey35"),
            axis.text.y=element_text(size=16, colour="grey35"),
            strip.text=element_text(size=16, colour="grey35"),
            plot.title=element_text(size=18, hjust=0.5, colour="grey35"),
            axis.title=element_text(size=16, colour="grey35"),
            axis.title.x=element_text(size=18, colour="grey35"),
            panel.background=element_rect(fill="white")
            ) +
      #scale_y_continuous(breaks=c()) + # remove y-scale when too many facets
      cowplot::panel_border(colour="grey35") +  
      theme(legend.position="none")
    
    # add histograms to empty plot
    if (nrow(drop_na(samppdf))>0) { 
      
      breaks <- my$breaks  

      # cat(file=stderr(), paste("xlim =", min(breaks), max(breaks)), "\n")
      
      stacked_histogram <- stacked_histogram +
        geom_rect(data=samppdf, mapping=aes(xmin=qrlower, xmax=qrupper, ymin=0, ymax=Inf), fill="lightcyan") +
        geom_histogram(data=samppdf, mapping=aes(x=pasture, colour=radius), fill=NA, size=1.1, binwidth=1) +
        geom_vline(data=samppdf, mapping=aes(xintercept=qr), size=1.5, colour="lightcyan4", alpha=0.2) +
        geom_vline(data=samppdf, mapping=aes(xintercept=q), size=1.5, colour="blue4") +
        geom_text(data=samppdf, mapping=aes(x=q, y=4, label=sprintf("%.1f t", q)),
                  colour="blue4", size=6, hjust=0, nudge_x=0.2) +
        facet_grid(radius ~ ., as.table=FALSE) + # as.table=FALSE reverses the order
        theme(strip.background=element_blank(), strip.text.y=element_text(angle=0)) +
        scale_x_continuous(breaks=breaks) +
        # scale_y_continuous(breaks=pretty_breaks(n=4)) +
        scale_y_continuous(breaks=NULL) +
        coord_cartesian(xlim=c(min(breaks),max(breaks)))
  
    } # end add histograms to empty plot
    
  }) # end isolate
  
  stacked_histogram

}) # end renderPlot
  
# show histogram
shinyUI(fluidPage(

    fluidRow(
      
      plotOutput("stacked_histogram")
      
    ) # end fluidRow
  
)) # end fluidPage

```

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