### Full cols4all GUI and table example

Source: https://cols4all.github.io/cols4all-R/reference/c4a_gui.html

Demonstrates launching the GUI and using the table function with various options, provided all necessary packages are installed and the session is interactive.

```R
if (requireNamespace("shiny") &&
  requireNamespace("shinyjs") &&
  requireNamespace("kableExtra") &&
  requireNamespace("colorblindcheck") &&
  interactive()) {

c4a_gui()

# categorical palettes with maximum number of colors
c4a_table(type = "cat")

# sort sequential palettes by hue
c4a_table(type = "seq", n = 7, sort = "H")

# sort sequential palettes by hue type (how many hues are used)
c4a_table(type = "seq", n = 5, sort = "hues")
}
```

--------------------------------

### Example: Plotting Brewer Set 1 Palette

Source: https://cols4all.github.io/cols4all-R/reference/c4a_plot.html

Demonstrates plotting the 'brewer.set1' palette with one row.

```R
c4a_plot("brewer.set1", nrows=1)
```

--------------------------------

### Install cols4all from CRAN

Source: https://cols4all.github.io/cols4all-R/index.html

Install the cols4all package from CRAN, including its dependencies.

```R
install.packages("cols4all", dependencies = TRUE)
```

--------------------------------

### Install cols4all Development Version

Source: https://cols4all.github.io/cols4all-R/index.html

Install the development version of the cols4all package from GitHub using the remotes package.

```R
install.packages("remotes")
remotes::install_github("cols4all/cols4all-R", dependencies = TRUE)
```

--------------------------------

### Install cols4all R Package

Source: https://cols4all.github.io/cols4all-R/articles/01_paper.html

Install the cols4all R package to access interactive tools for color palette analysis. This is the primary method for obtaining the package.

```r
install.packages("cols4all")
```

--------------------------------

### Get or set global options

Source: https://cols4all.github.io/cols4all-R/reference/c4a_options.html

The primary interface for interacting with package configuration.

```R
c4a_options(...)
```

--------------------------------

### Example: Plotting 'tol.pu_gn' Palette with CVD Simulation

Source: https://cols4all.github.io/cols4all-R/reference/c4a_plot.html

Demonstrates plotting the 'tol.pu_gn' palette including color-blindness simulations.

```R
c4a_plot_cvd("tol.pu_gn")
```

--------------------------------

### Example: Plotting 'greens' Palette with CVD Simulation

Source: https://cols4all.github.io/cols4all-R/reference/c4a_plot.html

Demonstrates plotting the 'greens' palette including color-blindness simulations.

```R
c4a_plot_cvd("greens")
```

--------------------------------

### Example: Plotting Brewer Set 1 with CVD Simulation

Source: https://cols4all.github.io/cols4all-R/reference/c4a_plot.html

Demonstrates plotting the 'brewer.set1' palette including color-blindness simulations.

```R
c4a_plot_cvd("brewer.set1")
```

--------------------------------

### Example: Plotting Brewer Set 1 with Hex Codes

Source: https://cols4all.github.io/cols4all-R/reference/c4a_plot.html

Demonstrates plotting the 'brewer.set1' palette and displaying its hex codes, with one row.

```R
c4a_plot_hex("brewer.set1", nrows=1)
```

--------------------------------

### Get Palette Overview

Source: https://cols4all.github.io/cols4all-R/reference/c4a_palettes.html

Provides a summary table of the number of palettes available per series and type.

```APIDOC
## GET /api/overview

### Description
Generates an overview table summarizing the count of color palettes for each series and type combination available in the cols4all package.

### Method
GET

### Endpoint
/api/overview

### Query Parameters
- **return.matrix** (boolean) - Optional - If TRUE, returns only a matrix of counts. Defaults to FALSE (returns a data frame with additional info).
- **zero.count.as.NA** (boolean) - Optional - If TRUE, zero counts are returned as NA. Defaults to FALSE.

### Response
#### Success Response (200)
- **overview** (object or matrix) - A table or matrix showing palette counts per series and type.

#### Response Example
```json
{
  "overview": [
    {
      "series": "viridis",
      "type": "seq",
      "count": 5
    },
    {
      "series": "magma",
      "type": "seq",
      "count": 5
    }
  ]
}
```
```

--------------------------------

### Retrieve palette scores

Source: https://cols4all.github.io/cols4all-R/reference/c4a_scores.html

Examples of retrieving scores for a single palette and batch processing multiple palettes.

```R
c4a_scores("blues3")

pals = c4a_palettes(type = "cat")
scores_cat7 = t(sapply(pals, c4a_scores, n = 7))

head(scores_cat7)
```

--------------------------------

### Example: Plotting a Met Bivc Palette

Source: https://cols4all.github.io/cols4all-R/reference/c4a_plot.html

Plots a specific bivariate color palette from the 'met' dataset.

```R
c4a_plot(.P$met$bivc$monet)
```

--------------------------------

### Example: Plotting a cols4all Bigv Palette

Source: https://cols4all.github.io/cols4all-R/reference/c4a_plot.html

Plots a specific bivariate color palette from cols4all, specifying 5 colors.

```R
c4a_plot(.P$cols4all$bivg$gn_bivg, n = 5)
```

--------------------------------

### Get an overview of palette counts

Source: https://cols4all.github.io/cols4all-R/reference/c4a_palettes.html

Provides a summary table showing the number of palettes per series and type.

```R
c4a_overview()
```

--------------------------------

### Launch Interactive Palette GUI

Source: https://cols4all.github.io/cols4all-R/articles/02_paletteer.html

Start the interactive graphical user interface (GUI) for exploring color palettes. This tool allows for filtering and sorting palettes based on various criteria.

```r
c4a_gui()
```

--------------------------------

### Example: Plotting a cols4all Bivs Palette

Source: https://cols4all.github.io/cols4all-R/reference/c4a_plot.html

Plots a specific bivariate color palette from cols4all, specifying 5 colors.

```R
c4a_plot(.P$cols4all$bivs$pu_gn_bivs, n = 5)
```

--------------------------------

### Overview of Available Palettes

Source: https://cols4all.github.io/cols4all-R/articles/02_paletteer.html

Get an overview of the number of available palettes from 'paletteer' in a matrix format. This helps in understanding the distribution of palettes by type and source.

```r
(m <- c4a_overview(return.matrix = TRUE))
```

--------------------------------

### Example: Plotting a cols4all Bivd Palette

Source: https://cols4all.github.io/cols4all-R/reference/c4a_plot.html

Plots a specific bivariate color palette from cols4all, specifying 5 colors.

```R
c4a_plot(.P$cols4all$bivd$pu_gn_bivd, n = 5)
```

--------------------------------

### Get Available Series

Source: https://cols4all.github.io/cols4all-R/reference/c4a_palettes.html

Lists the available series for organizing color palettes. Can return results as a data frame.

```APIDOC
## GET /api/series

### Description
Lists the available series used to organize color palettes in the cols4all package. The output can be formatted as a data frame.

### Method
GET

### Endpoint
/api/series

### Query Parameters
- **type** (string) - Optional - Filter series by palette type: 'all', 'cat', 'seq', 'div', 'cyc'. Defaults to 'all'.
- **as.data.frame** (boolean) - Optional - Whether to return the result as a data frame with descriptions. Defaults to TRUE.

### Response
#### Success Response (200)
- **series** (array of objects or strings) - A list of series names or data frame rows describing each series.

#### Response Example
```json
{
  "series": [
    {
      "name": "viridis",
      "description": "Perceptually uniform sequential colormap"
    },
    {
      "name": "magma",
      "description": "Perceptually uniform sequential colormap"
    }
  ]
}
```
```

--------------------------------

### Get Colors from a Palette and Missing Value Color

Source: https://cols4all.github.io/cols4all-R/index.html

Use `c4a` to retrieve a specified number of colors from a named palette (e.g., 'hcl.purple_green'). Use `c4a_na` to get the specific color designated for missing values within that palette.

```R
# select purple green palette from the hcl series:
c4a("hcl.purple_green", 11)
#>  [1] "#492050" "#82498C" "#B574C2" "#D2A9DB" "#E8D4ED" "#F1F1F1" "#C8E1C9"
#>  [8] "#91C392" "#4E9D4F" "#256C26" "#023903"

# get the associated color for missing values
c4a_na("hcl.purple_green")
#> [1] "#BABABA"
```

--------------------------------

### Get and plot a color palette

Source: https://cols4all.github.io/cols4all-R/reference/c4a.html

Retrieves colors from the 'brewer.set3' palette and plots them. Ensure the 'c4a_plot_hex' function is available for plotting.

```R
set3 <- c4a("brewer.set3")
c4a_plot_hex(set3, nrows = 1)
```

--------------------------------

### Get Available Palette Names and Series

Source: https://cols4all.github.io/cols4all-R/reference/c4a_palettes.html

Lists all available cols4all color palettes, organized by series and functional type. Use `.P` for interactive browsing in an IDE.

```R
c4a_palettes(
  type = c("all", "cat", "seq", "div", "cyc", "bivs", "bivc", "bivd", "bivg"),
  series = NULL,
  full.names = TRUE
)
```

```R
c4a_series(type = c("all", "cat", "seq", "div", "cyc"), as.data.frame = TRUE)
```

```R
c4a_types(series = NULL, as.data.frame = TRUE)
```

```R
c4a_overview(return.matrix = FALSE, zero.count.as.NA = FALSE)
```

```R
.P
```

--------------------------------

### Get information from a cols4all palette

Source: https://cols4all.github.io/cols4all-R/reference/c4a_scores.html

Retrieves detailed information and scores for a specified color palette from the cols4all package.

```APIDOC
## GET /api/c4a_scores

### Description
Retrieves information and scores for a cols4all color palette.

### Method
GET

### Endpoint
/api/c4a_scores

### Parameters
#### Query Parameters
- **palette** (string) - Optional - Name of the palette.
- **type** (string) - Optional - Type of palettes (if palette is not specified).
- **series** (string) - Optional - Series name (if palette is not specified).
- **n** (integer) - Optional - Number of colors. Defaults to NA.
- **no.match** (string) - Optional - Action to take if no match is found. Options: "message", "error", "null". Defaults to "message".
- **verbose** (boolean) - Optional - Whether to print messages. Defaults to TRUE.

### Response
#### Success Response (200)
- **name** (string) - Name of the palette.
- **series** (string) - Series the palette belongs to.
- **fullname** (string) - Full name of the palette.
- **type** (string) - Type of the palette (e.g., sequential, categorical).
- **palette** (array of strings) - The colors in the palette.
- **na** (string) - The color used for NA values.
- **nmax** (integer) - Maximum number of colors available in the palette.
- **reverse** (boolean) - TRUE if the palette name has a "-" prefix, indicating reversal.

### Request Example
```json
{
  "palette": "blues3",
  "n": 7
}
```

### Response Example
```json
{
  "name": "blues3",
  "series": "hcl",
  "fullname": "hcl.blues3",
  "type": "seq",
  "palette": ["#E5F5F9", "#C7EDF0", "#99D5C9", "#66C2A5", "#45A586", "#238B67", "#0C4534"],
  "na": "#FFFFFF",
  "nmax": 7,
  "reverse": false
}
```
```

--------------------------------

### Retrieve palette colors and missing value handling

Source: https://cols4all.github.io/cols4all-R/reference/c4a.html

Get specific colors for a palette and the designated color for missing values.

```R
c4a("carto.safe", 7)
```

```R
c4a_na("carto.safe")
```

--------------------------------

### Get Available Palette Names

Source: https://cols4all.github.io/cols4all-R/reference/c4a_palettes.html

Retrieves a list of all available color palettes, organized by series and type. Supports filtering by palette type and series.

```APIDOC
## GET /api/palettes

### Description
Retrieves a list of all available color palettes from the cols4all package. Palettes can be filtered by type and series.

### Method
GET

### Endpoint
/api/palettes

### Query Parameters
- **type** (string) - Optional - Type of color palette: 'all', 'cat', 'seq', 'div', 'cyc', 'bivs', 'bivc', 'bivd', or 'bivg'. Defaults to 'all'.
- **series** (string) - Optional - Series to list the palettes from. See `c4a_series` for options.
- **full.names** (boolean) - Optional - Whether to return full palette names including the series prefix. Defaults to TRUE.

### Response
#### Success Response (200)
- **palettes** (array of strings) - A list of palette names.

#### Response Example
```json
{
  "palettes": [
    "viridis.viridis",
    "magma.magma",
    "inferno.inferno"
  ]
}
```
```

--------------------------------

### Get Available Palette Types

Source: https://cols4all.github.io/cols4all-R/reference/c4a_palettes.html

Lists the different types of color palettes available, such as categorical, sequential, and diverging. Can return results as a data frame.

```APIDOC
## GET /api/types

### Description
Lists the available types for color palettes within the cols4all package, including categorical, sequential, diverging, cyclic, and bivariate types. The output can be formatted as a data frame.

### Method
GET

### Endpoint
/api/types

### Query Parameters
- **series** (string) - Optional - Filter types by a specific series. 
- **as.data.frame** (boolean) - Optional - Whether to return the result as a data frame with descriptions. Defaults to TRUE.

### Response
#### Success Response (200)
- **types** (array of objects or strings) - A list of palette type names or data frame rows describing each type.

#### Response Example
```json
{
  "types": [
    {
      "name": "cat",
      "description": "Categorical palette"
    },
    {
      "name": "seq",
      "description": "Sequential palette"
    }
  ]
}
```
```

--------------------------------

### Get a cols4all color palette

Source: https://cols4all.github.io/cols4all-R/reference/c4a.html

Functions to retrieve colors from specified palettes, handle missing values, and create color ramp functions.

```APIDOC
## Get a cols4all color palette

Source: `R/c4a.R`
`c4a.Rd`

`c4a` returns the colors of the specified palette, `c4a_na` returns the color for missing value that is associated with the specified palette, and `c4a_ramp` returns a color ramp function. Run `c4a_gui` to see all available palettes, which are also listed with `c4a_palettes`.

### Usage

```R
c4a(
  palette = NULL,
  n = NA,
  m = NA,
  type = c("cat", "seq", "div", "cyc", "bivs", "bivc", "bivd", "bivg"),
  reverse = FALSE,
  diag_flip = FALSE,
  order = NULL,
  range = NA,
  colorsort = "orig",
  format = c("hex", "rgb", "hcl", "RGB", "XYZ", "HSV", "HLS", "LAB", "polarLAB", "LUV",
    "polarLUV"),
  nm_invalid = c("error", "repeat", "interpolate"),
  verbose = TRUE
)

c4a_ramp(..., space = c("rgb", "Lab"), interpolate = c("linear", "spline"))

c4a_na(
  palette = NULL,
  type = c("cat", "seq", "div", "cyc", "bivs", "bivc", "bivd", "bivg"),
  verbose = TRUE
)
```

### Arguments 

`palette`
    
name of the palette. See `c4a_palettes` for available palettes. If omitted, the default palette is provided by `c4a_default_palette`. The palette name can be prefixed with a `-` symbol, which will reverse the palette (this can also be done with the `reverse` argument). For bivariate palettes, a `-` means reversed horizontally (columns), a `|`means reversed vertically (row), and a `+` means reversed in both directions. In addition, a `//` or `\` will flip the palette diagonally. This can be used in combination with `-`, `|`, or `+`. E.g. `-//` will reverse the columns and flip the palette diagonally.

`n`
    
number of colors. If omitted then: for type `cat` the maximum number of colors is returned, for types `seq`, `div`, and `cyc`, 7 , 9, and 9 colors respectively. For bivariate palettes `n` is the number of columns. 

`m`
    
number of rows in case type is bivariate, so one of `bivs`, `bivc`, `bivd` or `bivg` (see `c4a_types` for descriptions) 

`type`
    
type of color palette, in case `palette` is not specified: one of `cat`, `seq`, `div`, `cyc`, `bivs`, `bivc`, `bivd`, `bivg`. Run `c4a_types` for descriptions. 

`reverse`
    
should the palette be reversed? In case of a bivariate palette, a vector of two: the first indicates the horizontal direction (columns) and the second the vertical (rows). 

`diag_flip`
    
should a bivariate palette be flipped diagonally? 

`order`
    
order of colors. Only applicable for `cat` palettes 

`range`
    
a vector of two numbers between 0 and 1 that determine the range that is used for sequential and diverging palettes. The first number determines where the palette begins, and the second number where it ends. For sequential `seq` palettes, 0 means the leftmost (normally lightest) color, and 1 the rightmost (often darkest) color. For diverging `seq` palettes, 0 means the middle color, and 1 both extremes. If only one number is provided, this number is interpreted as the endpoint (with 0 taken as the start). 

`colorsort`
    
Sort the colors. Options: `orig` (original order), `Hx` (hue, where x is a starting number from 0 to 360), `C` (chroma), `L` (luminance). All these options are available for `cat` palettes, only the last one for `seq`, and none for the other palette types. 

`format`
    
format of the colors. One of: `hex` character vector of hex color values, `rgb` 3 column matrix of RGB values, `hcl` 3-column matrix of HCL values, or one of the color classes from `colorspace` 

`nm_invalid`
    
what should be done in case `n` or `m` is larger than the maximum number of colors or smaller than the minimum number? Options are `error` (an error is returned), `repeat` the palette is repeated, `interpolate` colors are interpolated. For categorical `cat` palettes only. 

`verbose`
    
should messages be printed? 

`...`
    
passed on to `c4a`. 

`space`
    
a character string; interpolation in RGB or CIE Lab color spaces 

`interpolate`
    
use spline or linear interpolation

### Value

A vector of colors (`c4a`) and a color (`c4a_na`)

### Examples

```R
# get the colors from brewer.set3 and plot them
set3 <- c4a("brewer.set3")
c4a_plot_hex(set3, nrows = 1)


c4a("hcl.set2", n = 36) |> c4a_plot_hex()

c4a("-hcl.set2", n = 12) |> c4a_plot_hex()


# how to know which palettes are avaiable?
# 1) Via the interactive tool:
if (FALSE) { # \dontrun{
  c4a_gui()
}
```
```

--------------------------------

### Get and plot a specific number of colors

Source: https://cols4all.github.io/cols4all-R/reference/c4a.html

Retrieves 36 colors from the 'hcl.set2' palette and plots them. This demonstrates specifying the number of colors using the 'n' argument.

```R
c4a("hcl.set2", n = 36) |> c4a_plot_hex()
```

--------------------------------

### Cite palettes using c4a_citation

Source: https://cols4all.github.io/cols4all-R/reference/c4a_citation.html

Use this function to get citation details for color palettes. Set verbose to FALSE to return only a bibentry object.

```r
c4a_citation("hcl")
```

```r
c4a_citation("poly.glasbey")
```

--------------------------------

### Get and plot a reversed color palette

Source: https://cols4all.github.io/cols4all-R/reference/c4a.html

Retrieves 12 colors from the 'hcl.set2' palette in reverse order and plots them. The '-' prefix on the palette name reverses the color order.

```R
c4a("-hcl.set2", n = 12) |> c4a_plot_hex()
```

--------------------------------

### Get cols4all palette information

Source: https://cols4all.github.io/cols4all-R/reference/c4a_info.html

Use this function to retrieve details about a cols4all palette. Specify the palette name and control the behavior when no match is found. The function returns a list containing palette name, series, full name, type, colors, NA color, maximum number of colors, and a boolean indicating if the palette is reversed.

```R
c4a_info(palette, no.match = c("message", "error", "null"), verbose = TRUE)
```

--------------------------------

### Load and Import paletteer Palettes

Source: https://cols4all.github.io/cols4all-R/articles/02_paletteer.html

Load the prepared system data from 'paletteer' and import it into 'cols4all'. This replaces the default 'cols4all' palettes with those from 'paletteer'.

```r
paletteer = readRDS(gzcon(url("https://cols4all.github.io/paletteer.rds")))
# from paletteer version 1.6.0

c4a_sysdata_import(paletteer)
```

--------------------------------

### Import and Export cols4all System Data

Source: https://cols4all.github.io/cols4all-R/reference/c4a_sysdata_import.html

Demonstrates exporting current system data and then importing it back. Verifies that the exported and re-imported data are identical.

```R
x = c4a_sysdata_export()
c4a_sysdata_import(x)
#> cols4all system data imported successfully
y = c4a_sysdata_export()
identical(x, y)
#> [1] TRUE
```

--------------------------------

### Explore available palettes interactively

Source: https://cols4all.github.io/cols4all-R/reference/c4a.html

Launches an interactive tool to view all available color palettes. This function is intended for interactive use and is wrapped in `if (FALSE)` to prevent execution during standard package checks.

```R
if (FALSE) { # \dontrun{
  c4a_gui()
} # }
```

--------------------------------

### Build palette data as is with c4a_data_as_is

Source: https://cols4all.github.io/cols4all-R/reference/c4a_data.html

Use `c4a_data_as_is` to build palette data without restructuring colors. It accepts arguments passed to `c4a_data` and defaults to not formatting palette names or removing grayscales.

```r
c4a_data_as_is(
  ...,
  format.palette.name = FALSE,
  remove.blacks = FALSE,
  remove.whites = FALSE,
  take.gray.for.NA = FALSE,
  remove.other.grays = FALSE,
  light.to.dark = FALSE,
  remove.names = FALSE
)
```

--------------------------------

### c4a_palettes()

Source: https://cols4all.github.io/cols4all-R/reference/index.html

Lists available palette names, series, and types within the package.

```APIDOC
## c4a_palettes()

### Description
Get available palette names and series.

### Method
Function Call

### Endpoint
c4a_palettes()
```

--------------------------------

### Configure color-blind friendliness thresholds

Source: https://cols4all.github.io/cols4all-R/reference/c4a_options.html

Adjusting thresholds for categorical palettes to change how color-blind friendliness is evaluated in the GUI.

```R
if (FALSE) { # \dontrun{
c4a_table(n = 9, sort = "cbfriendly")

opts = c4a_options("CBF_th", "CBVF_th")
opts$CBF_th$cat["min_dist"] = 7
opts$CBVF_th$cat["min_dist"] = 10


old = c4a_options(opts)

# more smileys :-) :-)
c4a_table(n = 9, sort = "cbfriendly")

# set the old settings back
c4a_options(old)
} # }
```

--------------------------------

### List available palette types

Source: https://cols4all.github.io/cols4all-R/reference/c4a_palettes.html

Displays the different types of color palettes supported by the package.

```R
c4a_types()
```

--------------------------------

### Load cols4all Package

Source: https://cols4all.github.io/cols4all-R/index.html

Load the cols4all package into the R session to access its functions.

```R
library(cols4all)
```

--------------------------------

### Graphical User Interface for Palettes

Source: https://cols4all.github.io/cols4all-R/reference/c4a_gui.html

Launches a Shiny app for interactive analysis of color palettes.

```APIDOC
## c4a_gui()

### Description
Launches a graphical user interface (Shiny app) for analyzing color palettes.

### Method
Function call

### Endpoint
N/A (R function)

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Request Example
```R
c4a_gui()
```

### Response
Launches a Shiny application in the user's default web browser.
```

--------------------------------

### Access palettes via .P

Source: https://cols4all.github.io/cols4all-R/reference/c4a.html

Directly access palette objects using the .P shorthand.

```R
.P$brewer$cat$set3
```

--------------------------------

### Sort sequential palettes by hue

Source: https://cols4all.github.io/cols4all-R/reference/c4a_gui.html

Displays sequential palettes with a specified number of colors, sorted by hue. Requires 'kableExtra'.

```R
c4a_table(type = "seq", n = 7, sort = "H")
```

--------------------------------

### Add Continuous Diverging Scale to ggplot2

Source: https://cols4all.github.io/cols4all-R/index.html

Use `scale_color_continuous_c4a_div` to apply a cols4all continuous diverging color scale to a ggplot2 plot. The 'mid' argument should be set appropriately, for example, to the mean of the data.

```R
# continuous diverging scale
ggplot(diam_exp, aes(x = carat, y = depth, color = price)) +
    geom_point(size = 2) +
    scale_color_continuous_c4a_div("wes.zissou1", mid = mean(diam_exp$price)) +
    theme_light()
```

--------------------------------

### Build and Load Palette Data

Source: https://cols4all.github.io/cols4all-R/reference/c4a_data.html

Functions to create, process, and register color palette data objects.

```APIDOC
## c4a_data

### Description
Builds palette data from a named list of color palettes or a c4a_info object. This function allows for restructuring palette colors and defining metadata.

### Parameters
#### Arguments
- **x** (list/c4a_info) - Required - Named list of color palettes or a c4a_info object.
- **xNA** (vector) - Optional - Colors for missing values.
- **types** (character) - Optional - Type of palette: "cat", "seq", "div", "cyc", "bivs", "bivc", "bivd", or "bivg".
- **series** (character) - Optional - Determines the series.
- **nmin, nmax, ndef** (numeric) - Optional - Minimum, maximum, and default number of colors.
- **mmin, mmax, mdef** (numeric) - Optional - Minimum, maximum, and default number of rows for bivariate palettes.
- **format.palette.name** (boolean) - Optional - Whether to format names to lowercase/underscore.
- **remove.blacks, remove.whites, take.gray.for.NA, remove.other.grays** (boolean) - Optional - Processing options for grayscale colors.
- **light.to.dark** (boolean) - Optional - Whether to order sequential palettes from light to dark.
- **remove.names** (boolean) - Optional - Whether to remove individual color names.
- **biv.method** (string) - Optional - Method to create bivariate palettes.
- **space** (string) - Optional - Color space for interpolation ("rgb" or "Lab").
- **range_matrix_args** (list) - Optional - Range specifications for sequential/diverging palettes.
- **bib** (bibentry) - Optional - Bibtex reference.
- **description** (string) - Optional - Description of the series.

### Response
- **c4a_data object** (list) - Returns a list containing data, s, citation, and description.

## c4a_load

### Description
Loads processed palette data into the cols4all environment.

### Parameters
- **data** (c4a_data) - Required - Data created with c4a_data.
- **overwrite** (boolean) - Optional - Whether to overwrite existing palettes.

## c4a_data_as_is

### Description
Builds palette data without restructuring the palette colors.

### Parameters
- **...** (dots) - Optional - Arguments passed to c4a_data.
- **format.palette.name, remove.blacks, remove.whites, take.gray.for.NA, remove.other.grays, light.to.dark, remove.names** (boolean) - Optional - Processing flags.
```

--------------------------------

### List available color palette series

Source: https://cols4all.github.io/cols4all-R/reference/c4a_palettes.html

Displays all available color palette series and their descriptions.

```R
c4a_series()
```

--------------------------------

### Define and apply custom nameability functions

Source: https://cols4all.github.io/cols4all-R/reference/c4a_options.html

Implementing a custom function to calculate color distance matrices and registering it via c4a_options.

```R
naming_RGB = function(pal) {
  cols = colorspace::hex2RGB(pal)
  coords = cols@coords

  cls = apply(coords, MARGIN = 1, which.max)
  mx = apply(coords, MARGIN = 1, max)
  dominance = ((mx + 0.001) / (rowSums(coords) + 0.001))
  cls[dominance < 0.4] = 4L

  m = matrix(0, nrow = length(pal), ncol = 4,
        dimnames = list(NULL, c("Red", "Green", "Blue", "Other")))
  for (i in 1:nrow(m)) {
    m[i, cls[i]] = 1
  }

  -m
}

# testing this function...
naming_RGB(c4a("brewer.set1")) #fair enough
#>       Red Green Blue Other
#>  [1,]  -1     0    0     0
#>  [2,]   0     0   -1     0
#>  [3,]   0    -1    0     0
#>  [4,]   0     0   -1     0
#>  [5,]  -1     0    0     0
#>  [6,]  -1     0    0     0
#>  [7,]  -1     0    0     0
#>  [8,]  -1     0    0     0
#>  [9,]   0     0    0    -1

# This vector should contain the 'prototype' colors, and have names that correspond
# to the column names of the returned matrices by the function above.
names_RGB =
    c("Red" = "#FF0000",
      "Green" = "#00FF00",
      "Blue" = "#0000FF",
      "Other" = "#AAAAAA")

# Set the options (may take a while because if calculated the nameability scores)
if (FALSE) { # \dontrun{
c4a_options(naming_fun = naming_RGB,
      naming_fun_args = list(),
      naming_colors = names_RGB)
} # }
```

--------------------------------

### Sort sequential palettes by number of hues

Source: https://cols4all.github.io/cols4all-R/reference/c4a_gui.html

Displays sequential palettes with a specified number of colors, sorted by the number of distinct hues used. Requires 'kableExtra'.

```R
c4a_table(type = "seq", n = 5, sort = "hues")
```

--------------------------------

### Display categorical palettes in a table

Source: https://cols4all.github.io/cols4all-R/reference/c4a_gui.html

Generates a table of categorical palettes. Requires the 'kableExtra' package for rendering.

```R
c4a_table(type = "cat")
```

--------------------------------

### Build palette data with c4a_data

Source: https://cols4all.github.io/cols4all-R/reference/c4a_data.html

Use `c4a_data` to build palette data, with options to restructure colors and handle missing values. It can also process `c4a_info` objects.

```r
c4a_data(
  x,
  xNA = NA,
  types = "cat",
  series = "x",
  nmin = NA,
  nmax = NA,
  ndef = NA,
  mmin = NA,
  mmax = NA,
  mdef = NA,
  format.palette.name = TRUE,
  remove.blacks = NA,
  remove.whites = NA,
  take.gray.for.NA = FALSE,
  remove.other.grays = FALSE,
  light.to.dark = FALSE,
  remove.names = TRUE,
  biv.method = "byrow",
  space = "rgb",
  range_matrix_args = list(NULL),
  bib = NA,
  description = NA
)
```

--------------------------------

### Show how to cite palettes

Source: https://cols4all.github.io/cols4all-R/reference/c4a_citation.html

This function allows users to retrieve citation information for color palettes or series within the cols4all package.

```APIDOC
## c4a_citation()

### Description
Show how to cite palettes

### Method
N/A (R function)

### Endpoint
N/A (R function)

### Parameters
#### Arguments 
- **name** (string) - Required - name of a palette or series 
- **verbose** (boolean) - Optional - should text be printed (if FALSE only a `utils::bibentry` object is returned)

### Request Example
```R
c4a_citation("hcl")
c4a_citation("poly.glasbey")
```

### Response
#### Success Response (200)
- **bibentry** (`utils::bibentry`) - A citation object for the specified palette or series.

#### Response Example
```
To cite palettes from series "hcl" in publications use:

Zeileis A, Hornik K, Murrell P (2009). "Escaping RGBland: Selecting Colors for Statistical Graphics." _Computational Statistics & Data Analysis_, *53*(9), 3259-3270. doi:10.1016/j.csda.2008.11.033 <https://doi.org/10.1016/j.csda.2008.11.033>.

@Article{hcl,
  title = {Escaping {RGB}land: Selecting Colors for Statistical Graphics},
  author = {Achim Zeileis and Kurt Hornik and Paul Murrell},
  journal = {Computational Statistics & Data Analysis},
  year = {2009},
  volume = {53},
  number = {9},
  pages = {3259--3270},
  doi = {10.1016/j.csda.2008.11.033},
}
```
```

--------------------------------

### List Available Color Palette Series

Source: https://cols4all.github.io/cols4all-R/index.html

Display a table of all available color palette series supported by the cols4all package, including their descriptions.

```R
c4a_series()
#>        series                                         description
#> 1      brewer                                ColorBrewer palettes
#> 2       carto                          Palettes designed by CARTO
#> 3    cols4all                  cols4all palettes (in development)
#> 4         gmt                 Palettes from General Mapping Tools
#> 5         hcl  Palettes from the Hue Chroma Luminance color space
#> 6      kovesi                   Palettes designed by Peter Kovesi
#> 7  matplotlib         Palettes from the Python library matplotlib
#> 8         met Palettes inspired by The Metropolitan Museum of Art
#> 9       meteo           Palettes by Oliver Fuhrer from MeteoSwiss
#> 10       misc                              Miscellaneous palettes
#> 11      ocean          Colormaps for Oceanography by Thyng et al.
#> 12      parks                 Palettes inspired by National Parks
#> 13       poly               Qualitative palettes with many colors
#> 14    powerbi                    Palettes from Microsoft Power BI
#> 15      scico             Scientific colour maps by Fabio Crameri
#> 16    seaborn            Palettes from the Python library Seaborn
#> 17    stevens                Bivariate palettes by Joshua Stevens
#> 18    tableau                        Palettes designed by Tableau
#> 19        tol                       Palettes designed by Paul Tol
#> 20        wes                   Palettes from Wes Anderson movies
```

--------------------------------

### List palettes by series and type

Source: https://cols4all.github.io/cols4all-R/reference/c4a.html

Retrieve lists of available palettes using the c4a_palettes function with optional filters.

```R
c4a_palettes(series = "brewer")
```

```R
c4a_palettes(type = "cat", series = "brewer")
```

--------------------------------

### System Data Import and Export

Source: https://cols4all.github.io/cols4all-R/reference/c4a_sysdata_import.html

Functions to import, export, and remove system data for cols4all.

```APIDOC
## Import and export system data

### Description
Import and export system data. `c4a_sysdata_import` will import system data and overwrite the current system data, `c4a_sysdata_export` will export the current system data, and `c4a_sysdata_remove` (partly) removes system data.

### Usage
```R
c4a_sysdata_import(data)
c4a_sysdata_export()
c4a_sysdata_remove(fullnames = NULL, series = NULL, are.you.sure = NA)
```

### Arguments

#### `c4a_sysdata_import(data)`
- **data** (cols4all data) - Description: cols4all data (see `c4a_data`)

#### `c4a_sysdata_export()`
- No arguments.

#### `c4a_sysdata_remove(fullnames = NULL, series = NULL, are.you.sure = NA)`
- **fullnames** (character vector) - Description: full palette names (so in the format `series.palette_name`)
- **series** (character vector) - Description: a character vector of series names that should be removed (use `"all"` to remove all).
- **are.you.sure** (logical) - Description: are you sure you want to remove series?

### Value
`c4a_sysdata_export` returns the system data (a list)

### Examples
```R
x = c4a_sysdata_export()
c4a_sysdata_import(x)
#> cols4all system data imported successfully
y = c4a_sysdata_export()
identical(x, y)
#> [1] TRUE
```
```

--------------------------------

### Load palette data with c4a_load

Source: https://cols4all.github.io/cols4all-R/reference/c4a_data.html

Use `c4a_load` to load previously built cols4all data. The `overwrite` argument controls whether existing palettes with the same name will be replaced.

```r
c4a_load(data, overwrite = FALSE)
```

--------------------------------

### Create and visualize color ramps

Source: https://cols4all.github.io/cols4all-R/reference/c4a.html

Generate color ramps and visualize them using the c4a_plot function.

```R
c4a("viridis", 100) |> c4a_plot()
```

```R
c4a_ramp("viridis")(100) |> c4a_plot()
```

--------------------------------

### Define and Load Pink Floyd Palettes

Source: https://cols4all.github.io/cols4all-R/reference/c4a_data.html

Defines a named list of hex color vectors and registers them as a new series in the cols4all package.

```R
pf = list(piper = c("#391C1C", "#C6C6AA", "#713939", "#C6391C",
    "#C6E3C6", "#AA7155", "#AA8E71", "#C68E71"),
      saucerful = c("#000000", "#1C1C1C", "#393939", "#FFFFFF",
    "#555555", "#8E8E71", "#E3C6AA", "#715539"),
      atom = c("#C6E3FF", "#397139", "#557139", "#E3E3C6",
    "#1C1C1C", "#1C551C", "#AAAA8E", "#8EC6E3"),
      meddle = c("#715539", "#553939", "#8E7155", "#71AAAA",
    "#8E8E71", "#1CAAE3", "#55C6E3", "#AA7155"),
      obscured = c("#000000", "#1C1C1C", "#393939", "#717155",
    "#8E8E71", "#715539", "#C6AA8E", "#E3C6AA"),
      moon = c("#000000", "#FF0000", "#FF9224", "#FFFF00",
    "#71C600", "#00C6FF", "#8E398E", "#FFFFFF"),
      wish = c("#FFFFFF", "#AAC6E3", "#8E8E8E", "#717155",
    "#555539", "#8E8E71", "#555555", "#8E7155"),
      animals = c("#391C39", "#393955", "#E3C671", "#718E8E",
    "#AAAA8E", "#C67139", "#AA5539", "#E3AA39"),
      wall = c("#FFFFFF", "#E3E3E3", "#C6C6C6", "#AAAAC6",
    "#1C1C1C", "#000000", "#8E8E8E", "#E3C6E3"),
      cut = c("#000000", "#E30000", "#AA0000", "#391C55",
    "#FFE3E3", "#1C1C00", "#FFAA55", "#8E8E55"),
      lapse = c("#000000", "#8E8EC6", "#8E8E71", "#7171AA",
    "#39391C", "#717171", "#AAAAAA", "#E3E3E3"),
      division = c("#000000", "#FFFFC6", "#00398E", "#AA8E55",
    "#39558E", "#C6AA71", "#39391C", "#555571"),
      more = c("#0055AA", "#FFAA1C", "#1C71AA", "#003971",
    "#E38E55", "#E3AAAA", "#718EAA", "#71718E"),
      umma = c("#AA8E71", "#555539", "#39391C", "#1C1C1C",
    "#E3E3C6", "#715539", "#391C1C", "#8E7155"),
      relics = c("#3955AA", "#1C3971", "#5571C6", "#715555",
    "#8E7155", "#E3AA71", "#8E8EAA", "#E3FFFF"),
      river = c("#393939", "#555555", "#39558E", "#C6C6C6",
    "#718EAA", "#1C1C1C", "#717171", "#E3C68E"))

if (requireNamespace("colorblindcheck", quietly = TRUE)) {
  pfdata = c4a_data_as_is(pf, series = "pinkfloyd",
    description = "Palettes extracted from Pink Floyd album covers")
  c4a_load(pfdata)

  c4a_series()
  c4a_overview()

  if (requireNamespace("shiny") &&
    requireNamespace("shinyjs") &&
    requireNamespace("kableExtra") &&
    requireNamespace("colorblindcheck") &&
    requireNamespace("plotly") &&
    interactive()) {
    c4a_gui(series = "pinkfloyd", n = 8)
  }
}
```

--------------------------------

### c4a_info()

Source: https://cols4all.github.io/cols4all-R/reference/index.html

Retrieves metadata and information about a specific cols4all palette.

```APIDOC
## c4a_info()

### Description
Get information from a cols4all palette.

### Method
Function Call

### Endpoint
c4a_info()
```