Map with ggplot2: Site localization

Data source

The data used for this tutorial are available here

Note

The senegal shape file was downloaded here

This tutorial is based on this published paper

Make sure you've installed all requiered packages.

Code

#Reset R's brain
rm(list=ls())

library(rgdal)

## Loading required package: sp

## rgdal: version: 1.3-6, (SVN revision 773)
##  Geospatial Data Abstraction Library extensions to R successfully loaded
##  Loaded GDAL runtime: GDAL 2.2.3, released 2017/11/20
##  Path to GDAL shared files: C:/Users/ANGE/Documents/R/win-library/3.5/rgdal/gdal
##  GDAL binary built with GEOS: TRUE 
##  Loaded PROJ.4 runtime: Rel. 4.9.3, 15 August 2016, [PJ_VERSION: 493]
##  Path to PROJ.4 shared files: C:/Users/ANGE/Documents/R/win-library/3.5/rgdal/proj
##  Linking to sp version: 1.3-1

library(mapdata)

## Loading required package: maps

library(mapproj)
library(maps)
library(ggplot2)
library(ggrepel)
library(legendMap)

## Loading required package: maptools

## Checking rgeos availability: TRUE

## Loading required package: grid

library(dplyr)

## Warning: package 'dplyr' was built under R version 3.5.3

## 
## Attaching package: 'dplyr'

## The following objects are masked from 'package:stats':
## 
##     filter, lag

## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union

#Set the working directory
setwd("C:/Users/ANGE/Documents/R MAP")

#Set the shapefile path
mySHP="C:/Users/ANGE/Documents/R MAP"

#Import the shapefile
myFile=readOGR (mySHP, layer="SEN_adm1", stringsAsFactors=FALSE)

## OGR data source with driver: ESRI Shapefile 
## Source: "C:\Users\ANGE\Documents\R MAP", layer: "SEN_adm1"
## with 14 features
## It has 9 fields
## Integer64 fields read as strings:  ID_0 ID_1

#Focus on the regions of interest

myregion = subset(myFile, myFile$ID_1 == "13" | 
                    myFile$ID_1 == "2" | 
                    myFile$ID_1 == "3" |
                    myFile$ID_1 == "6" |
                    myFile$ID_1 == "5" |
                    myFile$ID_1 == "12" |
                    myFile$ID_1 == "7" |
                    myFile$ID_1 == "10")



#Transform into the dataframe
myreg = fortify(myregion, region = "NAME_1")

#Rename long and lat 
myreg = rename(myreg, Longitude = long, Latitude= lat)

#Transform the shapefile into a dataframe
myDF = fortify(myFile)

## Regions defined for each Polygons

#Change long and lat into Longitude and Latitude
myDF = rename(myDF, Longitude = long, Latitude= lat)

#Import my data
mydata = read.csv("dat_revu.csv", header=TRUE, sep=";")


#Join the data to plot
plotData <- left_join(myreg, mydata)

## Joining, by = "id"

## Warning: Column `id` joining character vector and factor, coercing into
## character vector

#Make the plot

p <-  ggplot() +
      geom_polygon(data=myreg, linetype = "dotted", aes(x=Longitude, y=Latitude, group = group),colour="black", fill="white") +
      coord_map(projection = "lagrange") +
      scale_bar(lon = -17.75, lat = 13, 
                         distance_lon = 40, distance_lat = 10, 
                         distance_legend = 25, dist_unit = "km", 
                         arrow_length = 10, arrow_distance = 50, arrow_north_size = 6)+
      geom_point(data=mydata, aes(x=long, y=lat), color = "grey") +
      geom_label_repel(
        data=mydata, aes(x=long, y=lat, label=label, fill = Region),
        fontface = 'bold', color = 'white',
        box.padding = 0.35, point.padding = 0.5,
        segment.color = 'grey'
      ) +
      theme_minimal() +
      theme(panel.grid.major = element_line(colour = "black", size = 0.5, linetype = "dotted")) +
      theme(plot.background = element_rect(colour = "white", size = 1)) +
      ggtitle("Map of sampling sites")

Map rendering

Just call the map variable p

That is it!

But I am struggling to remove the "a" in the legend.So I renamed the sites with a. Any help will be welcomed.