tmap

Create an interactive map to explore your data.

Miriam Lerma true
2024-12-04

Intro

When analyzing tracking data in R, you may want to explore the locations. One option is to export the cleaned data set and open it a GIS program. However, R also offers interactive mapping features. In this post, I’ll walk you through the steps I used to create interactive maps with my GPS data.

Data

For the exercises, test data is from masked boobies.
To access the data you have to install the package sula: devtools::install_github(“MiriamLL/sula”)

library(sula)
Data_1original<-GPS_preparado

Transform

The function fortify helps the data frame to be more easily be plotted.

library(tidyverse)
Data_2fortify<-fortify(Data_1original)

Make sure your lat and lon are numerical

Data_2fortify$lat<-as.numeric(Data_2fortify$Latitude)
Data_2fortify$lon<-as.numeric(Data_2fortify$Longitude)

Transform to spatial.

library(sf)

Select which CRS you will like to use.

Data_3spatial <- st_as_sf(Data_2fortify, coords = c("lon", "lat"),crs = 4326, agr = "constant")

Select the columns that are of interest.

Data_4info<-Data_3spatial[,c("IDs","trip_number","dia_hora")]

Map

Install the package tmap.

This package allows you to create interactive maps.

library(tmap)

For making the map interactive, the mode view should be declared.

tmap_mode("view")

To create your map with points you can use the arguments tm_shape and tm_dots

tm_shape(Data_4info)+
   tm_dots()

To rename the information that shows, you can add the argument popup.vars

tm_shape(Data_4info)+
   tm_dots(id = "IDs",col="yellow",popup.vars=c("trip_number"="trip_number","dt"="dia_hora"))

To separate between individuals you can also include them as separated layers.

tm_shape(subset(Data_4info,Data_4info$ID=='GPS01'))+
   tm_dots(id = "IDs",col="yellow",popup.vars=c("trip_number"="trip_number","dt"="dia_hora"))+
  tm_shape(subset(Data_4info,Data_4info$ID=='GPS03'))+
   tm_dots(id = "IDs",col="red",popup.vars=c("trip_number"="trip_number","dt"="dia_hora"))

Interact with you map

Using you can zoom-in to see the points.
Using you can zoom-out to see the points.

Using you can select which layers to show.

Put the cursor on top of the dot , when appears click on it and you should be able to see the ID, trip number and dt and time of the point.

tm_shape(subset(Data_4info,Data_4info$ID=='GPS01'))+
   tm_dots(id = "IDs",col="yellow",popup.vars=c("trip_number"="trip_number","dt"="dia_hora"))+
  tm_shape(subset(Data_4info,Data_4info$ID=='GPS03'))+
   tm_dots(id = "IDs",col="red",popup.vars=c("trip_number"="trip_number","dt"="dia_hora"))

Using tmap might save you the step to export your dataframe, and the import it into another program, particularly if you want to check a particular point and particular information associated to that point.

Further reading