Type:	Package
Title:	Create Flashcards of Terms and Definitions
Version:	0.3.0
Maintainer:	Jeffrey R. Stevens <jeffrey.r.stevens@protonmail.com>
Description:	Provides functions for creating flashcard decks of terms and definitions. This package creates HTML slides using 'revealjs' that can be viewed in the 'RStudio' viewer or a web browser. Users can create flashcards from either existing built-in decks or create their own from CSV files or vectors of function names.
License:	MIT + file LICENSE
URL:	https://github.com/JeffreyRStevens/flashr, https://jeffreyrstevens.github.io/flashr/
BugReports:	https://github.com/JeffreyRStevens/flashr/issues
Depends:	R (≥ 2.10)
Imports:	cli, curl, gh, httr, memoise, revealjs, rmarkdown, testthat, utils
Suggests:	covr, knitr, litedown, withr
VignetteBuilder:	knitr
Config/testthat/edition:	3
Encoding:	UTF-8
LazyData:	true
RoxygenNote:	7.3.2
NeedsCompilation:	no
Packaged:	2025-05-07 18:34:53 UTC; jstevens
Author:	Jeffrey R. Stevens [aut, cre, cph]
Repository:	CRAN
Date/Publication:	2025-05-07 18:50:02 UTC

flashr: Create Flashcards of Terms and Definitions

Description

Provides functions for creating flashcard decks of terms and definitions. This package creates HTML slides using 'revealjs' that can be viewed in the 'RStudio' viewer or a web browser. Users can create flashcards from either existing built-in decks or create their own from CSV files or vectors of function names.

Author(s)

Maintainer: Jeffrey R. Stevens jeffrey.r.stevens@protonmail.com (ORCID) [copyright holder]

See Also

Useful links:

• https://github.com/JeffreyRStevens/flashr

• https://jeffreyrstevens.github.io/flashr/

• Report bugs at https://github.com/JeffreyRStevens/flashr/issues

Build data frame of functions for input to flashcard()

Description

To create a data frame of functions that can be used to create a flashcard deck, use build_functions_df(). This function calls extract_functions() to find the functions if the file argument is specified. Otherwise, users can pass a character vector of function names to the fs argument. Either way, a title must be passed to title to create the data frame.

Users can then either complete the description column of the data frame with their own descriptions or set the desc argument to TRUE to use descriptions from flashr_decks.

Usage

build_functions_df(file = NULL, fs = NULL, title, desc = TRUE, omit = TRUE)

Arguments

Value

Data frame suitable to include in flashcard().

See Also

Other functions for extracting code and functions: extract_code(), extract_functions()

Examples

build_functions_df(fs = c("apple", "apply", "+"), title = "Test")

Checks if a character input is valid

Description

Checks if a character input is valid

Usage

check_character(name = NULL, value = NULL, allowed = NULL, nullok = FALSE)

Arguments

Checks if a logical input is valid

Description

Checks if a logical input is valid

Usage

check_logical(name = NULL, value = NULL)

Arguments

Choose from available flashcard decks

Description

This function prints a list of flashcard decks to the console and let's the user choose one of the decks. By default, the function searches the flashr_decks repo. But other GitHub repos can be used.

To narrow the results, include text in the pattern argument (for example, choose_deck(pattern = "r4ds")).

Usage

choose_deck(
  pattern = NULL,
  choice = NULL,
  repo = "JeffreyRStevens/flashr_decks"
)

Arguments

Value

Outputs a list of available built-in flashcard decks to the console, where the user can choose one of the decks to generate flashcards.

Note

This function requires internet connectivity as it checks GitHub repos for decks.

See Also

Other functions for finding decks: list_decks()

Examples

## Not run: 
# Choose from all available decks in default repository
choose_deck()

# Choose from decks including text matching pattern
choose_deck(pattern = "r4ds")

# Choose from decks from specific repository
choose_deck(repo = "JeffreyRStevens/flashr_decks")

## End(Not run)

Create deck from vector of functions

Description

The create_deck() function generates a set of flashcards with randomly ordered pairs of terms and descriptions from a vector of functions provided by the user. The function outputs reveal.js presentation as an HTML file. If running in RStudio, the flashcards are output to the viewer. Otherwise, they are output to a web browser.

Usage

create_deck(
  x,
  title = NULL,
  termsfirst = TRUE,
  package = TRUE,
  theme = "moon",
  file = NULL,
  random = TRUE,
  fontsize = "default",
  fontcolor = NULL,
  linkcolor = NULL,
  use_browser = FALSE
)

Arguments

Value

An HTML file of terms and descriptions rendered in the RStudio viewer or web browser.

See Also

Other functions for creating decks: flashcard()

Examples

# Display terms then descriptions
my_functions <- c("as_tibble()", "bind_rows()", "c()")
create_deck(x = my_functions)

# Customize the title
create_deck(x = my_functions, title = "My deck")

# Save the HTML version of the flashcard deck locally
create_deck(x = my_functions, title = "My deck", file = "my_deck.html")

Data types deck

Description

This flashcard deck includes terms associated with data types and structures.

Usage

data_types

Format

A data frame with 4 columns.

term

reference term or function

description

description or definition of term

url

URL for function documentation

package

package including function/argument

title

title of deck

Extract code blocks from R Markdown or Quarto file

Description

To extract code blocks, apply extract_code() to R Markdown or Quarto files either locally or via a URL. This function returns a character vector where each line of content from an R code block is an element of the vector. Code block options are not returned—only the content of the block. Code blocks from other languages/engines (e.g., Python) are not returned.

Usage

extract_code(file, empty = TRUE, comments = TRUE)

Arguments

Value

Returns character vector of individual lines of code.

Note

This function is adapted from one Yihui Xie posted at https://yihui.org/en/2023/01/func-call/.

See Also

Other functions for extracting code and functions: build_functions_df(), extract_functions()

Examples

extract_code("https://raw.githubusercontent.com/JeffreyRStevens/flashr/refs/heads/main/README.Rmd")

Extract function calls from character vector of R code

Description

This function finds all of the R functions in a character vector of R code. For R scripts, first use readLines() or readr::read_file() to import the script into a character vector. For R Markdown or Quarto documents, first use extract_code() to find all of the R code in code blocks. The character vector can then be passed to extract_functions() to find all of the functions. By default, all instances of functions are returned. To omit duplicate functions, set duplicates = FALSE.

Usage

extract_functions(code, duplicates = TRUE)

Arguments

Value

Returns character vector of function names without parentheses (e.g., it returns "library" rather than "library()") included in R code.

Note

This function is adapted from one Yihui Xie posted at https://yihui.org/en/2023/01/func-call/.

See Also

Other functions for extracting code and functions: build_functions_df(), extract_code()

Examples

extract_functions(extract_code(
  "https://raw.githubusercontent.com/JeffreyRStevens/flashr/refs/heads/main/README.Rmd"
))

Gracefully fail if internet connection is not available

Description

CRAN policies require that "Packages which use Internet resources should fail gracefully with an informative message if the resource is not available or has changed (and not give a check warning nor error)." This solution is adapted from kvasilopoulos' response at https://forum.posit.co/t/internet-resources-should-fail-gracefully/49199/11. This function is not exported.

Usage

fail_gracefully(remote_file, maxtime = 10)

Arguments

Create flashcards

Description

The flashcard() function generates a set of flashcards with randomly ordered pairs of terms and descriptions from built-in flashcard decks. The function outputs reveal.js presentation as an HTML file. If running in RStudio, the flashcards are output to the viewer. Otherwise, they are output to a web browser.

Usage

flashcard(
  x,
  termsfirst = TRUE,
  package = TRUE,
  theme = "moon",
  file = NULL,
  random = TRUE,
  fontsize = "default",
  fontcolor = NULL,
  linkcolor = NULL,
  use_browser = FALSE,
  omit_na = TRUE
)

Arguments

Value

An HTML file of terms and descriptions rendered in the RStudio viewer or web browser.

Note

This function requires internet connectivity to use existing decks. An internet connection is not required if you supply a CSV file. However, without an internect connection, themes other than black, white, and serif, may not render properly, as they require access to Google Fonts.

See Also

Other functions for creating decks: create_deck()

Examples

# Display terms then descriptions
flashcard("data_types")

# Display descriptions then terms
flashcard("data_types", termsfirst = FALSE)

# Display terms without package information
flashcard("data_types", package = FALSE)

List available available flashcard decks

Description

This function searches for flashcard decks stored in GitHub repositories. By default, the function searches the flashr_decks repo. But other GitHub repos can be used.

To narrow the results, include text in the pattern argument (for example, list_decks(pattern = "r4ds")).

Usage

list_decks(
  pattern = NULL,
  repo = "JeffreyRStevens/flashr_decks",
  quiet = FALSE
)

Arguments

Details

You are welcome to fork the flashr_decks repo and modify or add your own decks. Or you can create your own repo from scratch. Just make sure to place your decks in a directory called ⁠decks/⁠ in your root directory. Then set the repo argument to your username and repo (see Examples).

Value

Outputs a list of available built-in flashcard decks to the console.

See Also

Other functions for finding decks: choose_deck()

Examples

# View all available decks
list_decks()

# View decks with text matching pattern
list_decks(pattern = "r4ds")

# View decks from specific repository
list_decks(repo = "JeffreyRStevens/flashr_decks")

Vectors deck

Description

This flashcard deck includes terms associated with vectors.

Usage

vectors

Format

A data frame with 4 columns.

term

reference term or function

description

description or definition of term

package

package including function/argument

title

title of deck