rasterly (version 0.2.0)

rasterly: Easily and rapidly generate raster image data with support for Plotly.js

Description

Create a rasterly object, to which aggregation layers may be added. This function is the first step in the process to generate raster image data using the rasterly package.

Usage

rasterly(
  data = NULL,
  mapping = aes(),
  ...,
  plot_width = 600,
  plot_height = 600,
  x_range = NULL,
  y_range = NULL,
  background = "white",
  color = NULL,
  show_raster = TRUE,
  drop_data = FALSE,
  variable_check = FALSE
)

Arguments

data

Dataset to use for generating the plot. If not provided, data must be supplied in each layer of the plot. For best performance, particularly when processing large datasets, use of data.table is recommended.

mapping

Default list of aesthetic mappings to use for plot. The same with ggplot2 aes. See details.

...

Other arguments which will be passed through to layers.

plot_width

Integer. The width of the image to plot; must be a positive integer. A higher value indicates a higher resolution.

plot_height

Integer. The height of the image to plot; must be a positive integer. A higher value indicates a higher resolution.

x_range

Vector of type numeric. The range of x; it can be used to clip the image. For larger datasets, providing x_range may result in improved performance.

y_range

Vector of type numeric. The range of y; it can be used to clip the image. For larger datasets, providing y_range may result in improved performance.

background

Character. The background color of the image to plot.

color

Vector of type character. It will determine this color vector is a color_map or color_key automatically.

• color_map: It has Color(s) used to draw each pixel. The color_map is extended by linear interpolation independently for RGB. The darkness of the mapped color depends upon the values of the aggregation matrix.

• color_key: Vector of type character. The color_key is used for categorical variables; it is passed when the color aesthetic is provided.

show_raster

Logical. Should the raster be displayed?

drop_data

Logical. When working with large datasets, drops the original data once processed according to the provided aes() parameters, using the remove() function. See details for additional information.

variable_check

Logical. If TRUE, drops unused columns to save memory; may result in reduced performance.

Value

An environment wrapped by a list which defines the properties of the raster data to be generated.

Details

• The rasterly package currently supports five aesthetics via aes(): x, y, on, color, and size. The "on" aesthetic specifies the variable upon which the reduction function should be applied to generate the raster data.

• drop_data can help save space, particularly when large datasets are used. However, dropping the original dataset may result in errors when attempting to set or update aes() parameters within rasterly layers.

See Also

rasterly_points, rasterly_build, [.rasterly, [<-.rasterly ggRasterly, plotRasterly

Examples

# NOT RUN {
 if(requireNamespace("data.table")) {
 url1 <- "https://raw.githubusercontent.com/plotly/datasets/master/uber-rides-data1.csv"
 ridesRaw_1 <-  url1 %>%
   data.table::fread(stringsAsFactors = FALSE)
 url2 <- "https://raw.githubusercontent.com/plotly/datasets/master/uber-rides-data2.csv"
 ridesRaw_2 <-  url2 %>%
   data.table::fread(stringsAsFactors = FALSE)
 url3 <- "https://raw.githubusercontent.com/plotly/datasets/master/uber-rides-data3.csv"
 ridesRaw_3 <-  url3 %>%
   data.table::fread(stringsAsFactors = FALSE) 
 ridesDf <- list(ridesRaw_1, ridesRaw_2, ridesRaw_3) %>% 
   data.table::rbindlist()
 
 ridesDf %>%
       rasterly(mapping = aes(x = Lat, y = Lon)) %>%
       rasterly_points()
 }
# }
# NOT RUN {
# }