Visualize gpx tracks from a folder on a picture from google maps.

gpx-visualization.R

library(plotKML)
library(maps)
library(ggmap)

# Settings
activities_folder = "/Users/noqqe/Downloads/activities/"
center_map_on = "Plech"
zoom_depth = 9  # 1 - 21
routes_color = "#FF000022"

# Get list of files
setwd(activities_folder)
files <- dir(pattern = "\\Ride.gpx")

# Initialize vectors
index <- c()
latitude <- c()
longitude <- c()

# Parse all files 
for (i in 1:length(files)) {
  
  route <- readGPX(files[i])
  location <- route$tracks[[1]][[1]]
  
  # build up vectors of all coordinates
  index <- c(index, rep(i, dim(location)[1]))
  latitude <- c(latitude, location$lat)
  longitude <- c(longitude, location$lon)
}

# Combine the three vectors into one data frame
routes <- data.frame(cbind(index, latitude, longitude))

# Get a google map centered on target with appropriate zoom (1 - 21)
nbgmap <- qmap(location = center_map_on, zoom = zoom_depth)

# map routes data onto the google map
nbgmap + geom_path(aes(x = longitude, y = latitude, group = factor(index)), 
                   colour = routes_color, data = routes, alpha=0.7)