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Plot an interpolated variable as a choropleth map

Source: R/plot-methods.R
plot.interpElections_result.Rd

Produces a ggplot2 choropleth map of an interpolated variable. Variables can be referenced by column name, ballot number, candidate name, or party abbreviation.

Usage

# S3 method for class 'interpElections_result'
plot(
  x,
  variable = NULL,
  quantity = "pct_tract",
  palette = "RdYlBu",
  breaks = "quantile",
  n_breaks = 5L,
  title = NULL,
  subtitle = NULL,
  legend_title = NULL,
  caption = NULL,
  show_sources = FALSE,
  border_color = "white",
  border_width = 0.05,
  limits = NULL,
  scale_bar = TRUE,
  ...
)

# S3 method for class 'interpElections_result'
autoplot(object, ...)

Arguments

x

An interpElections_result object.

variable

Variable to plot. Accepts a column name (e.g., "CAND_13"), ballot number (numeric, e.g. 13), candidate name substring (e.g., "Lula"), or party abbreviation (e.g., "PT"). Multiple values produce a faceted comparison. If NULL, auto-selects the first candidate variable.

quantity

Quantity to map: "pct_tract" (default), "absolute", "pct_muni", "pct_valid", "pct_eligible", "density".

palette

Color palette name. RColorBrewer palettes (e.g., "RdYlBu", "YlGnBu", "Spectral") or viridis palettes (e.g., "viridis", "magma", "plasma"). Default: "RdYlBu" (diverging, colorblind-friendly).

breaks

Scale breaks: "quantile" (default), "continuous", "jenks" (requires classInt), or a numeric vector of custom break points.

n_breaks

Number of breaks for "quantile" or "jenks". Default: 5.

title

Plot title. NULL = auto-generated from dictionary (title-cased candidate name with party).

subtitle

Plot subtitle. NULL = auto-generated from municipality/year/quantity metadata.

legend_title

Legend title. NULL = auto-generated from quantity type.

caption

Plot caption. NULL = auto-generated source note. Use "" to suppress.

show_sources

Overlay source points (polling stations) on the map. Requires electoral_sf in the result (use keep = "electoral_sf" when interpolating). Default: FALSE.

border_color

Tract border color. Default: "white".

border_width

Tract border width. Default: 0.05.

limits

Bounding box for the map extent as c(xmin, xmax, ymin, ymax) in the CRS of the data (typically longitude/latitude). NULL (default) shows the full extent. Use this to zoom into a region of interest.

scale_bar

Add a scale bar (requires ggspatial). Default: TRUE.

...

Ignored.

object

An interpElections_result object.

Value

A ggplot object (invisibly). Can be further customized with ggplot2 + syntax.

Examples

if (FALSE) { # \dontrun{
result <- interpolate_election_br(3304557, 2020, 2022)

# By candidate name (default: % of tract votes, quantile breaks)
plot(result, variable = "Lula")

# By ballot number
plot(result, variable = 13)

# Absolute counts with continuous scale
plot(result, variable = "PT", quantity = "absolute",
     breaks = "continuous")

# Faceted comparison
plot(result, variable = c("Lula", "Bolsonaro"))

# Zoom into a region
plot(result, variable = "Lula",
     limits = c(-43.2, -43.1, -22.95, -22.85))

# Composable with ggplot2
library(ggplot2)
plot(result, variable = "PT") + theme_dark()
} # }