plot_bar: Bar Plot

Description

Plots a Bertin, Ford (battleship curve) or Dice-Leraas diagram.

Usage

plot_bertin(object, ...)
plot_ford(object, ...)
# S4 method for CountMatrix
plot_bertin(object, threshold = NULL,
  scale = NULL)
# S4 method for CountMatrix
plot_ford(object, EPPM = FALSE)

Arguments

object

An object to be plotted.

...

Currently not used.

threshold

A function that takes a numeric vector as argument and returns a numeric threshold value (see below). If NULL (the default), no threshold is computed.

scale

A function used to scale each variable, that takes a numeric vector as argument and returns a numeric vector. If NULL (the default), no scaling is performed.

EPPM

A logical scalar: should the EPPM be drawn (see details)?

Value

A ggplot object.

Bertin Matrix

As de Falguerolles et al. (1997) points out: "In abstract terms, a Bertin matrix is a matrix of displays. [...] To fix ideas, think of a data matrix, variable by case, with real valued variables. For each variable, draw a bar chart of variable value by case. High-light all bars representing a value above some sample threshold for that variable."

Ford Diagram

If EPPM is TRUE and if a relative abundance is greater than the mean percentage of the type, the exceeding part is highlighted. This positive difference from the column mean percentage (in french "<U+00E9>cart positif au pourcentage moyen", EPPM) represents a deviation from the situation of statistical independence. As independence can be interpreted as the absence of relationships between types and the chronological order of the assemblages, EPPM is a useful graphical tool to explore significance of relationship between rows and columns related to seriation (Desachy 2004).

References

Bertin, J. (1977). La graphique et le traitement graphique de l'information. Paris: Flammarion. Nouvelle Biblioth<U+00E8>que Scientifique.

de Falguerolles, A., Friedrich, F. & Sawitzki, G. (1997). A Tribute to J. Bertin's Graphical Data Analysis. In W. Badilla & F. Faulbaum (eds.), SoftStat '97: Advances in Statistical Software 6. Stuttgart: Lucius & Lucius, p. 11-20.

Desachy, B. (2004). Le s<U+00E9>riographe EPPM: un outil informatis<U+00E9> de s<U+00E9>riation graphique pour tableaux de comptages. Revue arch<U+00E9>ologique de Picardie, 3(1), 39-56. DOI: 10.3406/pica.2004.2396.

Ford, J. A. (1962). A quantitative method for deriving cultural chronology. Washington, DC: Pan American Union. Technical manual 1.

Examples

Run this code

# NOT RUN {
## Abundance data
## Coerce dataset to a count matrix
mississippi_count <- as_count(mississippi)

## Plot a Bertin diagram...
## ...without threshold
plot_bertin(mississippi_count, threshold = NULL)
## ...with the variable mean as threshold
plot_bertin(mississippi_count, threshold = mean)

## ...with variables scaled to 0-1
scale_01 <- function(x) (x - min(x)) / (max(x) - min(x))
plot_bertin(mississippi_count, threshold = mean, scale = scale_01)

## Abundance data
## Coerce dataset to a count matrix (data from Desachy 2004)
compiegne_count <- as_count(compiegne)

## Plot a Ford diagram...
## ...without threshold
plot_ford(compiegne_count)
## ...with EPPM
plot_ford(compiegne_count, EPPM = TRUE)
# }

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