2016-12-01-multiple-layers-leaflet-widget-with-rstat.Rmd

---
title: "Add multiple layers in leaflet widget"
author: "Sébastien Rochette"
output:
  html_document: default
---

```{r setup, include=FALSE}
# Define output size for the leaflet widget
knitr::opts_chunk$set(
  fig.width = 4.5,
  fig.height = 4.5
)
```

```{r leaflet, echo = FALSE, message = FALSE, warning = FALSE}
library(leaflet)
library(rgdal)

# Working directory ------------------------------------------------------------
wd <- ""

# Read multiple shapefiles with standardised name ------------------------------
species <- c("Sole", "Maquerel", "Langoustine", "Merlan")
Groupnames <- c("Cas 1 : Sole", "Cas 2 : Maquereau", "Cas 3 : Langoustine",
                "Cas 4 : Merlan")

for (sp in species) {
  for (type in c("Avis", "TAC")) {
    files.sp <- readOGR(dsn = wd, layer = paste(sp, type, sep = "_"),
                        verbose = FALSE)
    assign(paste(sp, type, sep = "_"), files.sp)
  }
}

# Create leaflet widget --------------------------------------------------------
m <- leaflet() %>%
  addTiles(group = "OSM (default)") 

# Add multiple layers with a loop ----------------------------------------------
for (sp.N in 1:length(species)) {
  sp <- species[sp.N]
  for (type in c("Avis", "TAC")) {
    tmp <- get(paste(sp, type, sep = "_"))
    
    # Define different colors depending on type of data
    if (type == "Avis") {
      myPal <- colorRampPalette(c("blue", "skyblue", "navyblue"))
      factpal.Div <- colorFactor(myPal(length(tmp$id)), tmp$id)
      
      m <- m %>%
        addPolygons(data = tmp, 
                    fillColor = ~factpal.Div(tmp$id), 
                    color = "#000000", 
                    opacity = 1, 
                    fillOpacity = 0.8, 
                    stroke = TRUE,
                    weight = 1.5, 
                    smoothFactor = 0.2,
                    popup = paste0("Zone d'avis : ", tmp$id),
                    group = Groupnames[sp.N]
        ) 
    } else {
      myPal <- colorRampPalette(c("red", "orange", "brown"))
      factpal.Div <- colorFactor(myPal(length(tmp$id)), tmp$id)
      
      m <- m %>%
        addPolygons(data = tmp, 
                    fillColor = "#FF0000",
                    color = ~factpal.Div(tmp$id), 
                    opacity = 0.6, 
                    fillOpacity = 0.05, 
                    stroke = TRUE,
                    weight = 5, 
                    smoothFactor = 0.2,
                    popup = paste0("Zone de TAC : ", tmp$id),
                    group = Groupnames[sp.N]
        )
    }
  }
} # end of species

# Additional leaflet options ---------------------------------------------------
m <- m %>%
  # Add layers controls
  addLayersControl(
    baseGroups = Groupnames,
    options = layersControlOptions(collapsed = FALSE)
  ) %>%
  # Add common legend
  addLegend(colors = c("#4367F4", "#FF0000"),
            labels = c("Zones d'avis", "Zones de TAC"),
            opacity = c(0.8, 0.5))

# Print the map ----------------------------------------------------------------            
m
```
Widget réalisé par Sébastien de <http://statnmap.com>

***