automated text for reproducible research

Question

I am using RStudio, R Markdown, Latex, and Pandoc to clean data, construct variables, run my analysis, and report the results. I'm new to the concept of reproducible research, but I'm hooked. Makes a lot of sense.

Dynamic tables and figures are no problem. Dynamic text, however, is stumping me. I can insert inline code to say that 95% of all statistics are false, but I am not sure how I can vary my language in a reproducible way.

For instance, what if I have an object x=0.66 and I want to write "2 out of 3 dentists use Crest"? I can look at the current value of x, 0.66, and type "2 out of 3" in the text, but this is not reproducible. Let's say I get new data and rerun my analysis and x becomes 0.52. My text would be out of date. Sure, I could dynamically report that 52% of dentists prefer Crest, but a report gets stale when everything is reported as percentages.

My thought is that I could create functions that I could call in the text when I want to vary the writing. For instance, an "out.of" function could work on if else statements to produce the text:

ifelse(x < 0.09,"fewer than 1 out of 10",
ifelse(x >= 0.09) & x < 0.11,"roughly 1 out of 10",
ifelse(x >= 0.11 & x < 0.15,"slightly more than 1 out of 10",
ifelse(x >= 0.15 & x < 0.19,"nearly 2 out of 5",
ifelse(x >= 0.19 & x < 0.21,"roughly 2 out of 5",
...
ifelse(x >= 0.95 & x < 0.99,"nearly all",
ifelse(x >= 0.99,"all","fubar"))...)

I could also create a fraction function that would do something similar for one-tenth, two-fifths, one-third...

I'm sure others have tackled this issue already. Any leads? Ideas?

Answer 1

There is a package FRACTION and when you replace / by "out of", it could work. However, the output when using the number of decimals is strange:

library(FRACTION)
fra(0.66,j=2)
# [1] "33 / 50"
fra(0.66,j=1)
#"7 / 1e+08" 

Edit by @Dieter Menne: forget this, see @Ben Bolker below.