Title:	Visualization and Analysis of Nominal Variable Distributions
Version:	1.0.2
Description:	Provides tools for visualizing and analyzing the shape of discrete nominal frequency distributions. The package introduces centered frequency plots, in which nominal categories are ordered from the most frequent category at the center toward less frequent categories on both sides, facilitating the detection of distributional patterns such as uniformity, dominance, symmetry, skewness, and long-tail behavior. In addition, the package supports Pareto charts for the study of dominance and cumulative frequency structure in nominal data. The package is designed for exploratory data analysis and statistical teaching, offering visualizations that emphasize distributional form rather than arbitrary category ordering.
License:	MIT + file LICENSE
Encoding:	UTF-8
RoxygenNote:	7.3.3
Depends:	R (≥ 4.1.0)
LazyData:	true
Imports:	dplyr, ggplot2
Suggests:	knitr, rmarkdown, testthat (≥ 3.0.0)
VignetteBuilder:	knitr
Config/testthat/edition:	3
NeedsCompilation:	no
Packaged:	2026-03-21 18:26:31 UTC; norberello
Author:	Norberto Asensio [aut, cre]
Maintainer:	Norberto Asensio <norberto.asensio@ehu.eus>
Repository:	CRAN
Date/Publication:	2026-03-21 18:40:02 UTC

Alice in Wonderland word dataset

Description

Tokenized words from Alice's Adventures in Wonderland by Lewis Carroll. Each row represents a single word occurrence, allowing analysis of word frequency distributions and demonstration of Zipf-like behavior in natural language.

Usage

alice

Format

A data frame with one column:

word

Character. Tokenized word from the text.

Source

Public domain text (Lewis Carroll, 1865)

Categories: Uniform Distribution of Bikinibottom Species

Description

A dataset of dummy nominal data inspired by characters/species from the Bikini Bottom universe (SpongeBob SquarePants). This dataset simulates a roughly uniform distribution across 11 species, with a total of 250 observations. It was intentionally designed to be uniform-like for testing nominal distribution visualization functions.

A simple dataset of categorical values used for examples.

Usage

categories

categories

Format

A data frame with 250 rows and 1 variable:

animal

Character. Species/animal names. 11 species inspired by Bikini Bottom.

A data frame with 1 column:

animal

Factor with animal categories as letters

Source

Generated for examples

Examples

categories
# Ranked bar plot of species frequencies
ranked_barplot(categories, "animal")

# Centered bar plot (most frequent in the center)
centered_barplot(categories, "animal")

# Centered dot plot with theoretical shape overlays
shape_comp_plot(categories, "animal")

Categories2: Triangular Distribution of Bikinibottom Species

Description

A dataset of dummy nominal data inspired by characters/species from the Bikini Bottom universe (SpongeBob SquarePants). This dataset simulates a roughly triangular distribution of frequencies.

Usage

categories2

Format

A data frame with 250 rows and 11 variables:

animal

Character. Species/animal names.

freq

Integer. Frequency of each species, forming a triangular pattern.

Examples

ranked_barplot(categories2, "animal")

Categories3: Exponential/Dominance Distribution of Bikinibottom Species

Description

A dataset of dummy nominal data inspired by characters/species from the Bikini Bottom universe (SpongeBob SquarePants). This dataset simulates a highly skewed distribution where a few species dominate most of the frequency (long-tail / exponential pattern). It was intentionally designed for pedagogical purposes to demonstrate dominance and Pareto-like behavior in nominal data.

Usage

categories3

Format

A data frame with 250 rows and 1 variable:

animal

Character. Species/animal names. 11 species inspired by Bikini Bottom.

Examples

categories3
# Centered dot plot showing exponential/long-tail pattern
shape_comp_plot(categories3, "animal")

# Pareto chart highlighting cumulative frequency and dominance
pareto(categories3, "animal")

# Optional: ranked or centered bar plots
ranked_barplot(categories3, "animal")
centered_barplot(categories3, "animal")

Categories4: Structured (triangular / normal-like) nominal distribution

Description

A dataset of dummy nominal data inspired by characters or species from the Bikini Bottom universe (SpongeBob SquarePants).

Usage

categories4

Format

A data frame with 250 rows and 1 variable:

animal

Character or species name (11 categories inspired by Bikini Bottom).

Details

The dataset represents a structured nominal distribution in which a limited number of categories dominate, followed by a gradual and approximately symmetric decline in frequencies. This pattern is consistent with a triangular or normal-like shape rather than a strongly long-tailed (Pareto/exponential) distribution.

The dataset was intentionally designed for pedagogical purposes to illustrate dominance, symmetry, and modal structure in nominal data, and to serve as a contrast with truly long-tailed distributions included elsewhere in the package.

Examples

categories4

# Centered dot plot showing a structured (normal-like) pattern
shape_comp_plot(categories4, "animal")

# Pareto chart showing dominance without a strong long tail
pareto(categories4, "animal")

# Ranked and centered bar plots
ranked_barplot(categories4, "animal")
centered_barplot(categories4, "animal")

Centered Frequency Bar Plot for Nominal Variables Creates a centered bar plot for discrete nominal variables by placing the most frequent category at the center and progressively less frequent categories alternately to the left and right.

Description

Centered Frequency Bar Plot for Nominal Variables Creates a centered bar plot for discrete nominal variables by placing the most frequent category at the center and progressively less frequent categories alternately to the left and right.

Usage

centered_barplot(df, var, title = NULL, scale = c("count", "percent"))

Arguments

Value

A ggplot2 object.

Examples

centered_barplot(categories, "animal")
centered_barplot(categories, "animal", scale = "percent")

Centered Dot Plot for Nominal Variables

Description

Creates a centered dot plot for a nominal variable, ordering categories from the most frequent at the center toward less frequent categories on both sides. Optionally connects points with a line and shades the area under the line.

Usage

centered_dotplot(
  df,
  var,
  connect = FALSE,
  shade = FALSE,
  scale = c("count", "percent")
)

Arguments

Value

A ggplot2 object.

Examples

centered_dotplot(categories, "animal")
centered_dotplot(categories, "animal", connect = TRUE)
centered_dotplot(categories, "animal", connect = TRUE, shade = TRUE)
centered_dotplot(mpg, "manufacturer", scale = "percent")

Central Concentration Index for Nominal Variables

Description

Computes a measure of how concentrated counts are around the center of a nominal variable, based on the centered plotting order.

Usage

central_concentration(df, var, top_k = 3, weighted = FALSE)

Arguments

Value

A numeric value between 0 and 1 representing the central concentration.

Examples

central_concentration(categories, "animal")
central_concentration(categories2, "animal", top_k = 5)
central_concentration(categories3, "animal", weighted = TRUE)

Dominance Index for Nominal Variables

Description

Computes dominance for a nominal variable using the Simpson index, quantifying the degree to which a few categories dominate the distribution.

Usage

dominance_index(df, var)

Arguments

Details

Dominance is calculated as:

D = \sum p_i^2

where p_i is the relative frequency of category i.

Higher values indicate stronger dominance by fewer categories.

Value

A numeric value representing dominance.

Examples

dominance_index(categories, "animal")
dominance_index(categories2, "animal")
dominance_index(categories3, "animal")

The Metamorphosis word dataset

Description

Tokenized words from The Metamorphosis by Franz Kafka. Each row represents a single word occurrence, allowing analysis of word frequency distributions and comparison with Zipf's law.

Usage

kafka

Format

A data frame with one column:

word

Character. Tokenized word from the text.

Source

Public domain text (Franz Kafka, 1915; English translation)

MPG dataset

Description

Car fuel economy data (from ggplot2) for examples.

Usage

mpg

Format

A data frame

Source

ggplot2::mpg

Pareto Plot for Nominal Variables

Description

Creates a Pareto chart for a nominal variable, displaying frequencies and cumulative percentages.

Usage

pareto(df, var, show_table = TRUE)

Arguments

Value

A ggplot2 object representing the Pareto chart.

Examples

pareto(categories, "animal")

Pielou's Evenness for Nominal Variables

Description

Computes Pielou's evenness index based on Shannon entropy for a nominal variable recorded as individual-level observations.

Usage

pielou_evenness(df, var)

Arguments

Details

Pielou's evenness is defined as:

E = H / \log(S)

where H is Shannon entropy and S is the number of observed categories.

Values range from 0 (complete dominance by one category) to 1 (perfectly even distribution).

Value

A numeric value representing Pielou's evenness.

Examples

pielou_evenness(categories, "animal")
pielou_evenness(categories2, "animal")
pielou_evenness(categories3, "animal")

Ranked Bar Plot for Nominal Variables

Description

Creates a bar plot for a nominal variable, with categories ordered from most frequent to least frequent.

Usage

ranked_barplot(df, var, scale = c("count", "percent"), title = NULL)

Arguments

Value

A ggplot2 object representing the ranked bar plot.

Examples

ranked_barplot(categories, "animal")
ranked_barplot(categories, "animal", scale = "percent")

Ranked Dot Plot for Nominal Variables

Description

Creates a ranked dot plot for a nominal variable, displaying category frequencies or percentages from highest to lowest. Optionally connects points with a line and shades the area under the line.

Usage

ranked_dotplot(
  df,
  var,
  connect = FALSE,
  shade = FALSE,
  scale = c("count", "percent")
)

Arguments

Value

A ggplot2 object.

Examples

ranked_dotplot(categories, "animal")
ranked_dotplot(categories, "animal", connect = TRUE)
ranked_dotplot(categories, "animal", connect = TRUE, shade = TRUE)
ranked_dotplot(mpg, "manufacturer", scale = "percent")

Rarefaction curve for nominal variables

Description

Generates a rarefaction curve showing the expected number of distinct categories discovered as sampling effort increases. The curve is estimated using Monte Carlo permutations of the observation order.

Usage

rare_plot(df, var, reps = 1000, max_effort = NULL)

Arguments

Value

Invisibly returns a data frame containing:

• effort: sampling effort

• mean: expected number of categories

• lowCI: lower confidence interval

• highCI: upper confidence interval

Examples

rare_plot(categories3, "animal")
rare_plot(ufo, "shape", reps = 25, max_effort = 500)

Fit Nominal Data to Theoretical Shapes Using AIC (Safe Exponential)

Description

Computes the multinomial log-likelihood of observed counts against four theoretical distributions (uniform, triangular, normal-like, and exponential/Pareto-like) and returns AIC and DeltaAIC values.

Usage

shape_aic(df, var, rate_exp = 0.7, eps = 1e-12)

Arguments

Value

A data.frame with columns: Shape, AIC, DeltaAIC.

Compare Observed Nominal Distribution with Theoretical Shapes

Description

Plots a centered dotplot of a nominal variable and overlays four theoretical distributions: uniform, triangular, exponential (Pareto-like), and normal-like.

Usage

shape_comp_plot(df, var, rate_exp = 0.7, scale = c("count", "percent"))

Arguments

Details

The function orders categories from most frequent at the center outwards. Observed frequencies are plotted as points and lines, and each theoretical distribution is overlaid with a different color and line type.

Value

A ggplot2 object.

Examples

shape_comp_plot(categories, "animal")
shape_comp_plot(categories2, "animal")
shape_comp_plot(categories3, "animal")

Star Wars dataset

Description

Character info from Star Wars (from dplyr/ggplot2 examples)

Usage

starwars

Format

A data frame

Source

dplyr::starwars

Tail Index for Nominal Variables

Description

Computes the proportion of categories contributing to the lower part of the distribution. Useful to quantify long-tail structure in nominal distributions.

Usage

tail_index(df, var, threshold = 0.8)

Arguments

Value

Numeric between 0 and 1 representing the tail proportion.

Examples

tail_index(categories3, "animal")
tail_index(categories2, "animal", threshold = 0.9)

UFO Sightings Dataset

Description

Sample data of UFO sightings used for examples.

A large real-world dataset of UFO sighting reports collected by the National UFO Reporting Center (NUFORC), a non-profit organization dedicated to the collection and dissemination of objective UFO data.

Usage

ufo

ufo

Format

A data frame with 8 columns:

city

Character. City where the UFO was reported.

comments

Character. Description or comments about the sighting.

date_sighted

Date. Date of the sighting.

duration_sec

Numeric. Duration of the sighting in seconds.

latitude

Numeric. Latitude of the sighting location.

longitude

Numeric. Longitude of the sighting location.

shape

Factor. Shape of the UFO observed. This is the nominal variable of interest.

state

Character. State of the sighting location.

A data frame with 63,561 rows and 8 variables:

date_sighted

Character. Date of the UFO sighting (YYYY-MM-DD).

latitude

Numeric. Latitude of the sighting location.

longitude

Numeric. Longitude of the sighting location.

city

Character. City where the sighting occurred.

state

Character. State or region of the sighting.

shape

Character. Reported shape of the UFO (nominal variable of interest).

duration_sec

Numeric. Duration of the sighting in seconds.

comments

Character. Free-text comments describing the sighting.

Details

The dataset contains over 63,000 reported sightings spanning several decades and includes information on sighting date, geographic location, duration, narrative comments, and—most importantly for nomiShape— the reported shape of the observed object.

The shape variable is a nominal variable with many categories (e.g., "light", "circle", "triangle", "sphere"), exhibiting strong dominance by a few common shapes followed by a gradual decline across rarer categories. Despite the presence of a highly frequent leading category ("light"), the overall frequency structure is better described as triangular or normal-like rather than strictly exponential or Pareto.

This dataset is included as a realistic, large-sample example for exploring dominance, modality, and shape classification of nominal distributions using visual and information-theoretic tools.

Source

Example dataset

National UFO Reporting Center (NUFORC), https://nuforc.org

Examples

ufo

# Centered bar plot highlighting dominance and symmetry
centered_barplot(ufo, "shape")

# Centered dot plot with connections and shading
centered_dotplot(ufo, "shape", connect = TRUE, shade = TRUE)

# Shape comparison plot
shape_comp_plot(ufo, "shape")

# AIC-based shape classification
shape_aic(ufo, "shape")

Rank-frequency (Zipf) plot for nominal variables

Description

Generates a rank-frequency plot comparing observed category frequencies with the expected Zipf distribution (inverse rank relationship).

Usage

zipf_rank_plot(df, var, max_rank = NULL, top_prop = NULL, loglog = FALSE)

Arguments

Value

Invisibly returns a data frame with rank-frequency information.

Examples

zipf_rank_plot(kafka, "word")
zipf_rank_plot(alice, "word", loglog=TRUE)
zipf_rank_plot(alice, "word", max_rank = 250)