Style a data.frame or list prior to converting to geojson

This helps you add styling following the Simplestyle Spec. See Details

Usage

geojson_style(
  input,
  var = NULL,
  var_col = NULL,
  var_sym = NULL,
  var_size = NULL,
  var_stroke = NULL,
  var_stroke_width = NULL,
  var_stroke_opacity = NULL,
  var_fill = NULL,
  var_fill_opacity = NULL,
  color = NULL,
  symbol = NULL,
  size = NULL,
  stroke = NULL,
  stroke_width = NULL,
  stroke_opacity = NULL,
  fill = NULL,
  fill_opacity = NULL
)

Arguments

input

A data.frame or a list

var

(character) A single variable to map colors, symbols, and/or sizes to

var_col

(character) A single variable to map colors to.

var_sym

(character) A single variable to map symbols to.

var_size

(character) A single variable to map size to.

var_stroke

(character) A single variable to map stroke to.

var_stroke_width

(character) A single variable to map stroke width to.

var_stroke_opacity

(character) A single variable to map stroke opacity to.

var_fill

(character) A single variable to map fill to.

var_fill_opacity

(character) A single variable to map fill opacity to

color

(character) Valid RGB hex color. Assigned to the variable marker-color

symbol

(character) An icon ID from the Maki project https://labs.mapbox.com/maki-icons/ or a single alphanumeric character (a-z or 0-9). Assigned to the variable marker-symbol

size

(character) One of 'small', 'medium', or 'large'. Assigned to the variable marker-size

stroke

(character) Color of a polygon edge or line (RGB). Assigned to the variable stroke

stroke_width

(numeric) Width of a polygon edge or line (number > 0). Assigned to the variable stroke-width

stroke_opacity

(numeric) Opacity of a polygon edge or line (0.0 - 1.0). Assigned to the variable stroke-opacity

fill

(character) The color of the interior of a polygon (GRB). Assigned to the variable fill

fill_opacity

(character) The opacity of the interior of a polygon (0.0-1.0). Assigned to the variable fill-opacity

Details

The parameters color, symbol, size, stroke, stroke_width, stroke_opacity, fill, and fill_opacity expect a vector of size 1 (recycled), or exact length of vector being applied to in your input data.

This function helps add styling data to a list or data.frame following the Simplestyle Spec (https://github.com/mapbox/simplestyle-spec/tree/master/1.1.0), used by MapBox and GitHub Gists (that renders geoJSON/topoJSON as interactive maps).

There are a few other style variables, but deal with polygons

GitHub has a nice help article on geoJSON files https://help.github.com/articles/mapping-geojson-files-on-github/

Please do get in touch if you think anything should change in this function.

Examples

if (FALSE) {
## from data.frames - point data
library("RColorBrewer")
smalluscities <-
  subset(us_cities, country.etc == "OR" | country.etc == "NY" | country.etc == "CA")

### Just color
geojson_style(smalluscities,
  var = "country.etc",
  color = brewer.pal(length(unique(smalluscities$country.etc)), "Blues")
)
### Just size
geojson_style(smalluscities, var = "country.etc", size = c("small", "medium", "large"))
### Color and size
geojson_style(smalluscities,
  var = "country.etc",
  color = brewer.pal(length(unique(smalluscities$country.etc)), "Blues"),
  size = c("small", "medium", "large")
)

## from lists - point data
mylist <- list(
  list(latitude = 30, longitude = 120, state = "US"),
  list(latitude = 32, longitude = 130, state = "OR"),
  list(latitude = 38, longitude = 125, state = "NY"),
  list(latitude = 40, longitude = 128, state = "VT")
)
# just color
geojson_style(mylist,
  var = "state",
  color = brewer.pal(length(unique(sapply(mylist, "[[", "state"))), "Blues")
)
# color and size
geojson_style(mylist,
  var = "state",
  color = brewer.pal(length(unique(sapply(mylist, "[[", "state"))), "Blues"),
  size = c("small", "medium", "large", "large")
)
# color, size, and symbol
geojson_style(mylist,
  var = "state",
  color = brewer.pal(length(unique(sapply(mylist, "[[", "state"))), "Blues"),
  size = c("small", "medium", "large", "large"),
  symbol = "zoo"
)
# stroke, fill
geojson_style(mylist,
  var = "state",
  stroke = brewer.pal(length(unique(sapply(mylist, "[[", "state"))), "Blues"),
  fill = brewer.pal(length(unique(sapply(mylist, "[[", "state"))), "Greens")
)

# from data.frame - polygon data
smallstates <- states[states$group %in% 1:3, ]
head(smallstates)
geojson_style(smallstates,
  var = "group",
  stroke = brewer.pal(length(unique(smallstates$group)), "Blues"),
  stroke_width = c(1, 2, 3),
  fill = brewer.pal(length(unique(smallstates$group)), "Greens")
)
}