calculate {vegalite}

Derive new fields

Description

Derive new fields

Usage

calculate(vl, field, expr)

Arguments

vl

Vega-Lite object created by vegalite

field

the field name in which to store the computed value.

expr

a string containing an expression for the formula. Use the variable "datum" to refer to the current data object.

Examples

vegalite() %>%
  add_data("https://vega.github.io/vega-editor/app/data/population.json") %>%
  add_filter("datum.year == 2000") %>%
  calculate("gender", 'datum.sex == 2 ? "Female" : "Male"') %>%
  encode_x("gender", "nominal") %>%
  encode_y("people", "quantitative", aggregate="sum") %>%
  encode_color("gender", "nominal") %>%
  scale_x_ordinal(band_size=6) %>%
  scale_color_nominal(range=c("#EA98D2", "#659CCA")) %>%
  facet_col("age", "ordinal", padding=4) %>%
  axis_x(remove=TRUE) %>%
  axis_y(title="population", grid=FALSE) %>%
  axis_facet_col(orient="bottom", axisWidth=1, offset=-8) %>%
  facet_cell(stroke_width=0) %>%
  mark_bar()