Short moveVis example on how to colour paths based on a continuous variable

moveVis_colours_by_variable.R

# use moveVis >= 0.10.2 for this example
library(moveVis)
library(move)
library(plyr)

# get example data. align movement to unique times and regular resolution
data("move_data")
m.aligned <- align_move(move_data, res = 4, unit = "mins")

# let's create some fake continous variable by splitting the moveStack into single tracks
m.split <- mapply(x = split(m.aligned), y = c(25, 11, 16), function(x, y){
  x$var <- round(sin(seq(0,10, length.out = length(x)))*y)+y+1
  return(x)
})
# now, each move object has a column "var" with some values (this could be anything,
# e.g. heart rate, temperature etc.)

# let's create a colour ramp function and assign colours for each value in "var"
colfun <- colorRampPalette(c("navy", "blue", "lightblue", "purple", "violetred"))
m.split <- lapply(m.split, function(x){
  x$colour <- mapvalues(x$var, 1:max(x$var), colfun(max(x$var)))
  return(x)
})
# now, we have a colour column with individual colours per value for each individual

# finally, merge the tracks back togehter into a stack...
m <- moveStack(m.split)

# ...and create frames from it
frames <- frames_spatial(m, map_service = "mapbox", map_type = "satellite", map_token = "YOUR_MAPBOX_TOKEN",
                         trace_show = T, path_legend = F, equidistant = F, path_fade = T) %>% 
  add_timestamps(type = "label") %>% 
  add_progress() %>% 
  add_northarrow(colour = "white") %>% 
  add_scalebar(colour = "white") %>% 
  add_labels(x = "Longitude", y = "Latitude")

# animate the frames
animate_frames(frames, "moveVis_colours_by_variable.gif",  width = 800, height = 550,
               end_pause = 1)