Add extract_expressions()

[IndrajeetPatil]

Similar to how extract_stats() lets you extract data frames, this function will help you extract all expressions present in the plot.

This will also help get rid of the output argument.

How to make this work with grouped_ plots?

[IndrajeetPatil]

Already implemented:

library(ggstatsplot)

p <- ggscatterstats(mtcars, wt, mpg)
#> Registered S3 method overwritten by 'ggside':
#>   method from   
#>   +.gg   ggplot2

extract_caption(p)
#> list(log[e] * (BF["01"]) == "-17.84", widehat(rho)["Pearson"]^"posterior" == 
#>     "-0.84", CI["95%"]^HDI ~ "[" * "-0.92", "-0.73" * "]", italic("r")["beta"]^"JZS" == 
#>     "1.41")

extract_subtitle(p)
#> list(italic("t")["Student"] * "(" * 30 * ")" == "-9.56", italic(p) == 
#>     "1.29e-10", widehat(italic("r"))["Pearson"] == "-0.87", CI["95%"] ~ 
#>     "[" * "-0.93", "-0.74" * "]", italic("n")["pairs"] == "32")

^{Created on 2023-01-03 with reprex v2.0.2}

As for what to do with the grouped plots, this is the same issue as #815.