add_screengrid {mapdeck}

Add Screengrid

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

...

clear_legend and clear_view arguments passed to 'clear_()' functions

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
)