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Bar chart of preference distribution for one contest

Source: R/quick_plots.R
dop_bar.Rd

Draws a bar chart showing how votes or preferences are distributed across items (candidates, parties, options) in a single contest or round. Bars are ordered from highest to lowest value.

Usage

dop_bar(data, items, value_col = NULL, round_col = "round", at_round = 1)

Arguments

data

A data frame in wide or long format. See Details.

items

<tidy-select> Columns to plot. Interpretation depends on format:

  • Wide: A tidy-select expression identifying the item columns to pivot, e.g. ALP:Other or -c(round, winner).

  • Long: A single column containing item names, e.g. PartyAb.

value_col

<tidy-select> Long format only. Column containing the numeric values to plot (vote shares or counts). When NULL (default), wide format is assumed and this argument is ignored.

round_col

Character. Name of the column used to identify rounds. Default "round", matching dop_irv() output. Override when your data uses a different column name (e.g., "CountNumber").

at_round

Integer. The round number to display. Default is 1.

Value

A ggplot object.

Details

dop_bar() accepts data in two formats, detected automatically via value_col:

Wide format (value_col = NULL, the default)

One row per round, one column per item. This is the direct output of dop_irv():

round | ALP  | LNP  | Other | winner
    1 | 0.40 | 0.35 | 0.25  | ALP
    2 | 0.52 | 0.48 | 0.00  | ALP

Supply the item columns via items (e.g., ALP:Other or -c(round, winner)) and select the round to display with at_round. Use round_col if your round column is named something other than "round" (e.g., round_col = "CountNumber").

Long format (value_col provided)

One row per item, with the item name and its value in separate columns. This is the format of aecdop_2022 and similar raw electoral datasets:

DivisionNm | CountNumber | PartyAb | CalculationValue
Adelaide   |           0 | ALP     |            0.40
Adelaide   |           0 | LNP     |            0.35
Adelaide   |           0 | Other   |            0.25

Supply the item name column via items, the value column via value_col, and the round to display via at_round. Use round_col if your round column is named something other than "round" (e.g., round_col = "CountNumber").

See also

dop_irv() to generate wide-format input from raw ballot data.

Examples

library(ggplot2)

# Wide format: output of dop_irv()
votes <- prefio::preferences(c("A > B > C", "B > A > C", "C > B > A",
                                "A > B > C", "A > C > B"))
irv_result <- dop_irv(votes)
dop_bar(irv_result, items = -c(round, winner), at_round = 1)


# Long format: pre-filter to desired contest, then plot
long_df <- aecdop_2022 |>
  dplyr::filter(
    CalculationType == "Preference Percent",
    CountNumber == 0,
    DivisionNm == "Adelaide"
  )
dop_bar(long_df, items = PartyAb, value_col = CalculationValue,
       round_col = "CountNumber", at_round = 0)