Interactive versions of the maps

The same map, rendered by leaflet: pan, zoom, and click a cell for its value. For looking at a surface while working on it, and for a report where the reader should be able to find their own bay.

Usage

leaflet_surface(
  x,
  value = NULL,
  by = NULL,
  coords = NULL,
  crs = NULL,
  label = NULL,
  transform = "auto",
  limits = NULL,
  probs = c(0, 0.99),
  popup = NULL,
  tiles = "Esri.WorldGrayCanvas",
  opacity = 0.8,
  legend = TRUE
)

leaflet_probability(
  x,
  value = NULL,
  by = NULL,
  coords = NULL,
  crs = NULL,
  label = NULL,
  limits = c(0, 1),
  popup = NULL,
  tiles = "Esri.WorldGrayCanvas",
  opacity = 0.8,
  legend = TRUE
)

leaflet_diverging(
  x,
  value = NULL,
  midpoint,
  by = NULL,
  coords = NULL,
  crs = NULL,
  label = NULL,
  limits = NULL,
  probs = c(0.01, 0.99),
  direction = 1,
  popup = NULL,
  tiles = "Esri.WorldGrayCanvas",
  opacity = 0.8,
  legend = TRUE
)

Arguments

x, value, by, coords, crs, label: Passed to as_map_data(), exactly as for map_surface(). crs here only says what the incoming coordinates are; it does not choose a projection, because leaflet is always Web Mercator.
transform, limits, probs: Passed to surface_scale(), so the colours match the static map's exactly.
popup: Extra columns of x to show when a cell is clicked, as a character vector. The value and the join key are always shown. FALSE turns popups off.
tiles: A leaflet provider name for the basemap, or NULL for no basemap at all. The default is "Esri.WorldGrayCanvas", a quiet grey one, so the data is the brightest thing on the map rather than competing with a road network. It is also key-free: see the note on leaflet_base().
opacity: How opaque the cells are over the basemap.
legend: Whether to draw the legend.
midpoint, direction: For leaflet_diverging(), as in map_diverging().

Value

A leaflet widget.

Why these exist rather than a call to leaflet

Not for the rendering – leaflet does that. For the decisions. Handing a grid to leaflet::colorNumeric() re-decides the scale at the call site, and it decides differently: linear, over the full data range, with no capping. So the static figure and the interactive one show the same numbers in different colours, and a reader who has seen both has been told two things. These reuse the same scale objects, so a cell is the same colour in both.

What is not carried over

The projection is leaflet's: Web Mercator, with WGS84 inputs, so display_crs() does not apply and everything is transformed to EPSG:4326. Land comes from the tile provider rather than from coastline() – which means, unlike every static map here, these need the network at draw time. That is the reason the static ones do not use tiles.

The legend

Swatches at the same breaks the static legend uses, with the same labels – including the >= on a capped scale. It is a stepped legend for a continuous ramp, which is what leaflet draws well; the colours between the swatches are continuous as they are on the static map.

Examples

if (FALSE) { # \dontrun{
grid <- example_grid()

leaflet_surface(grid, "density", label = "animals per km2")
leaflet_probability(grid, "occupancy", popup = c("density", "cv"))
leaflet_diverging(grid, "mess", midpoint = 0, direction = -1)
} # }