add_gg: Add 'ggplot2' function to frames
In moveVis: Movement Data Visualization

Description Usage Arguments Details Value Author(s) See Also Examples

This function adds ggplot2 functions (e.g. to add layers, change scales etc.) to the animation frames created with frames_spatial.

1	add_gg(frames, gg, data = NULL, ..., verbose = T)

`frames`	list of `ggplot2` objects, crated with `frames_spatial`.
`gg`	`ggplot2` expressions (see details), either as an expression of one or a list of `ggplot2` functions to be added to every frame, a list of such of the same length as `frames` to add different `ggplot2` expressions per frame
`data`	optional data used by `gg` (see details), either an object of any class, e.g. a `data.frame`, used by `gg` that will be added to all frames, a list, e.g. of multiple `data.frames`, with length of `frames` to add different data to each frame.
`...`	additional (non-iterated) objects that should be visible to `gg`.
`verbose`	logical, if `TRUE`, messages and progress information are displayed on the console (default).

Agrument gg expects ggplot2 functions handed over as expressions (see expr) to avoid their evaluation before thex are called for the correct frame. Simply wrap your ggplot2 function into expr() and supply it to gg. To add multiple ggplot2 functions to be applied on every frame, supply an expression containing a list of ggplot2 functions (e.g. expr(list(geom_label(...), geom_text(...)))). This expression would be added to all frames. To add specific ggplot2 functions per frame, supply a list of expressions of the same length as frames. Each expression may contain a list of ggplot2 functions, if you want to add multiple functions per frame.

If data is used, the ggplot2 expressions supplied with gg can use the object by the name data for plotting. If data is a list, it must be of the same length as frames. The list will be iterated, so that functions in gg will have access to the individual objects within the list by the name data per each frame. If the data you want to display is does not change with frames and may only be a character vector or similiar, you may not need data, as you can supply the needed values within the expression supplied through gg.

If you supply gg as a list of expressions for each frame and data as a list of objects (e.g. data.frames) for each frame, each frame will be manipulated with the corresponding ggplot2 function and the corresponding data.

List of frames.

Jakob Schwalb-Willmann

frames_spatial frames_graph animate_frames

library(moveVis)
library(move)
library(ggplot2)

data("move_data", "basemap_data")
# align movement
m <- align_move(move_data, res = 4, unit = "mins")


frames <- frames_spatial(m, map_service = "osm", map_type = "watercolor")
frames[[100]] # take a look at one of the frames

# let's draw a polygon on frames:
data <- data.frame(x = c(8.917, 8.924, 8.924, 8.916, 8.917),
                   y = c(47.7678, 47.7675, 47.764, 47.7646, 47.7678))
                   
frames = add_gg(frames, gg = expr(geom_path(aes(x = x, y = y), data = data,
                                            colour = "red", linetype = "dashed")), data = data)
                        
# add some text
frames <- add_text(frames, "Static feature", x = 8.9205, y = 47.7633,
                    colour = "black", size = 3)
frames[[100]]

# add_gg can also be used iteratively to manipulate each frame differently.
# Let's create unique polygons per frame:

# create data.frame containing corner coordinates
data <- data.frame(x = c(8.96, 8.955, 8.959, 8.963, 8.968, 8.963, 8.96),
                   y = c(47.725, 47.728, 47.729, 47.728, 47.725, 47.723, 47.725))
# make a list from it by replicating it by the length of frames
data <- rep(list(data), length.out = length(frames))

# now alter the coordinates to make them shift
data <- lapply(data, function(x){
  y <- rnorm(nrow(x)-1, mean = 0.00001, sd = 0.0001) 
  x + c(y, y[1])
})

# draw each individual polygon to each frame
frames = add_gg(frames, gg = expr(geom_path(aes(x = x, y = y), data = data,
                                            colour = "black")), data = data)
                                            
# add a text label
frames <- add_text(frames, "Dynamic feature", x = 8.959, y = 47.7305,
                   colour = "black", size = 3)
frames[[100]]

# animate frames to see how the polygons "flip"
animate_frames(frames, out_file = tempfile(fileext = ".mov"))

# you can use add_gg on any list of ggplot2 objects,
# also on frames made using frames_gr
r_list <- basemap_data[[1]]
r_times <- basemap_data[[2]]

frames.gr <- frames_graph(m, r_list = r_list, r_times = r_times, r_type = "gradient",
                          fade_raster = TRUE, graph_type = "hist", val_by = 0.01)
frames.gr[[100]]                         
# manipulate the labels, since they are very dense:
# just replace the current scale
frames.gr <- add_gg(frames.gr, expr(scale_x_continuous(breaks=seq(0,1,0.1),
                                    labels=seq(0,1,0.1), expand = c(0,0))))
frames.gr[[100]]