add_screengrid: Add Screengrid

In mapdeck: Interactive Maps Using 'Mapbox GL JS' and 'Deck.gl'

Description

The Screen Grid Layer takes in an array of latitude and longitude coordinated points, aggregates them into histogram bins and renders as a grid

Usage

add_screengrid(
  map,
  data = get_map_data(map),
  lon = NULL,
  lat = NULL,
  polyline = NULL,
  weight = NULL,
  aggregation = c("sum", "mean", "min", "max"),
  colour_range = NULL,
  opacity = 0.8,
  cell_size = 50,
  layer_id = NULL,
  update_view = TRUE,
  focus_layer = FALSE,
  digits = 6
)

Arguments

map	a mapdeck map object
data	data to be used in the layer. All coordinates are expected to be EPSG:4326 (WGS 84) coordinate system
lon	column containing longitude values
lat	column containing latitude values
polyline	optional column of data containing the polylines, if using encoded polylines
weight	the weight of each value. Default 1
aggregation	one of 'min', 'mean', 'max', 'sum'. If supplied it specifies how the weights used.
colour_range	vector of 6 hex colours
opacity	opacity of cells. Value between 0 and 1. Default 0.8
cell_size	size of grid squares in pixels. Default 50
layer_id	single value specifying an id for the layer. Use this value to distinguish between shape layers of the same type. Layers with the same id are likely to conflict and not plot correctly
update_view	logical indicating if the map should update the bounds to include this layer
focus_layer	logical indicating if the map should update the bounds to only include this layer
digits	number of digits for rounding coordinates

Details

add_screengrid supports POINT and MULTIPOINT sf objects

data

If the data is a simple feature object, the geometry column is automatically detected. If the sf object contains more than one geometry column and you want to use a specific one, you'll need to set the active geometry using sf::st_geometry( x ) <- "your_column" , where "your_column" is the name of the column you're activating. See ?sf::st_geometry

Examples

## You need a valid access token from Mapbox
key <- 'abc'
set_token( key )

df <- read.csv(paste0(
'https://raw.githubusercontent.com/uber-common/deck.gl-data/master/',
'examples/3d-heatmap/heatmap-data.csv'
))

df <- df[ !is.na(df$lng), ]
df$weight <- sample(1:10, size = nrow(df), replace = TRUE)

mapdeck( style = mapdeck_style('dark'), pitch = 45 ) %>%
add_screengrid(
  data = df
  , lat = "lat"
  , lon = "lng"
  , weight = "weight",
  , layer_id = "screengrid_layer"
  , cell_size = 10
  , opacity = 0.3
)

## as an sf object
library(sfheaders)
sf <- sfheaders::sf_point( df, x = "lng", y = "lat")

mapdeck( style = mapdeck_style('dark'), pitch = 45 ) %>%
add_screengrid(
  data = sf
  , weight = "weight",
  , layer_id = "screengrid_layer"
  , cell_size = 10
  , opacity = 0.3
)

mapdeck documentation built on Sept. 4, 2020, 9:07 a.m.