New format_markdown() function

In response to issue #1 this function try to solve the need of a parser function for expression objects returned by any of `{ggtatsplot}` or `{statsExpressions}` functions for reporting purposes in R Markdown

API

@@ -6,6 +6,7 @@ add_expression_col(data, paired = FALSE, statistic.text = NULL, effsize.text = N
 centrality_description(data, x, y, type = "parametric", tr = 0.2, k = 2L, ...)
 contingency_table(data, x, y = NULL, paired = FALSE, type = "parametric", counts = NULL, ratio = NULL, k = 2L, conf.level = 0.95, sampling.plan = "indepMulti", fixed.margin = "rows", prior.concentration = 1, top.text = NULL, ...)
 corr_test(data, x, y, type = "parametric", k = 2L, conf.level = 0.95, tr = 0.2, bf.prior = 0.707, top.text = NULL, ...)
+format_markdown(expr, ...)
 long_to_wide_converter(data, x, y, subject.id = NULL, paired = TRUE, spread = TRUE, ...)
 meta_analysis(data, type = "parametric", random = "mixture", k = 2L, conf.level = 0.95, top.text = NULL, ...)
 one_sample_test(data, x, type = "parametric", test.value = 0, alternative = "two.sided", k = 2L, conf.level = 0.95, tr = 0.2, bf.prior = 0.707, effsize.type = "g", top.text = NULL, ...)

NAMESPACE

@@ -14,6 +14,7 @@ export(centrality_description)
 export(contingency_table)
 export(corr_test)
 export(enframe)
+export(format_markdown)
 export(format_value)
 export(long_to_wide_converter)
 export(meta_analysis)

R/format_markdown.R

@@ -0,0 +1,89 @@
+#' @title Format expression to R Markdown
+#' @name format_markdown
+#'
+#' @description
+#'
+#'  Pass the expression generated using any of the functions to
+#'  get statistical details ready for the writing reports in R Markdown
+#'
+#' @param expr The expression returned inside the data.frame containing
+#' statistical details
+#' @param ... Currently ignored
+#'
+#' @examples
+#' \donttest{
+#' # for reproducibility
+#' set.seed(123)
+#' library(statsExpressions)
+#' options(tibble.width = Inf, pillar.bold = TRUE, pillar.neg = TRUE)
+#'
+#' # without changing defaults
+#' result <- corr_test(
+#'   data = ggplot2::midwest,
+#'   x    = area,
+#'   y    = percblack
+#' )
+#'
+#' format_markdown(result$expression)
+#'
+#' result <- oneway_anova(
+#'   data = iris_long,
+#'   x = condition,
+#'   y = value,
+#'   paired = TRUE
+#' )
+#'
+#' format_markdown(result$expression)
+#'
+#' }
+#' @export
+
+format_markdown <- function(expr, ...) {
+
+  # trasnform expression to be able to modify it
+  if (is.list(expr)) expr <- expr[[1]]
+  expr <- as.list(x = as.list(expr)[[1]])
+
+  # replace invalid patterns to be evaluated
+  expr <- gsub(")[", ") * \"\"[", expr, fixed = TRUE)
+  expr <- gsub("](", "] * list2(", expr, fixed = TRUE)
+  expr <- gsub("~", "%@%", expr, fixed = TRUE)
+
+  # transform to again to expression to evaluate it
+  expr <- lapply(expr, str2lang)
+  expr <- as.call(expr)
+
+  # global variables; could be changed for anything else
+  p <- "p"; CI <- "CI"; chi <- "*X*";
+  mu <- "*mu*"; log <- "log"; BF <- "BF";
+  e <- "e"; epsilon <- "Epsilon"; R <- "R";
+  HDI <- "HDI"; xi <- "xi"; omega <- "Omega";
+
+  # list works pasting expressions
+  list <- function(...) paste(..., sep = ", ")
+
+  # `list2` works the same but only for expressions with >= 1 parameter(s)
+  list2 <- function(...) paste0("(", paste(..., sep = ", "), ")")
+
+  # italic text just has stars around it
+  italic <- function(s) paste0("*", s, "*")
+
+  # wide hat has no effect on final output
+  widehat <- function(s) as.character(s)
+
+  # single subscripts are entered using subsetting
+  `[` <- function(main, subscript) paste0(main, "~", subscript, "~")
+
+  # single superscript are entered using symbol in both sides
+  `^` <- function(main, superscript) paste0(main, "^", superscript, "^")
+
+  # this symbol will concatenate
+  `*` <- function(lhs, rhs) paste0(lhs, rhs, collapse = ", ")
+  `%@%` <- function(lhs, rhs) paste0(lhs, rhs)
+
+  # replace to equal sign
+  `==` <- function(lhs, rhs) paste0(lhs, " = ", rhs)
+
+  # evaluate the expression to produce a string
+  eval(expr)
+}