Standardized output of test statistics with \Sexpr

Question

I try to get Latex and knitr to do a standardized \Sexpr{} output of statistics.

Example: I computed a correlation with

mycor<-cor.test(a,b)

Let's say the result would be:

Pearson's product-moment correlation

data:  a and b
t = 2.9413, df = 54, p-value = 0.004805
alternative hypothesis: true correlation is not equal to 0
95 percent confidence interval:
0.1204668 0.5780293
sample estimates:
cor
0.3715985

How can I "teach" LaTeX to generate the output

r(54)=.37, p < .01

without having to write

$r(\Sexpr{mycor$parameter)=\Sexpr{mycor$estimate}$, $p < .05$

all the time?

I want to write a command which does this for every correlation I report. Please note that I look for a possibility to let it transform p = 0.004805 to p<.01 automatically.

BTW: I tried to do it with

\newcommand{\repcor}[1]{$r(\Sexpr{#1$parameter)=\Sexpr{#1$estimate}$}

but this doesn't work...

Thank you in advance! Benjamin

Answer 1

Why not just write a function to output what you want. For example, at the start of your document, have:

<<echo=FALSE, tidy=FALSE>>=
trans = function(mycor) {

  out1 = paste0("$r(", mycor$parameter, ") = ", signif(mycor$estimate, 2), "$,")

  p = mycor$p.value
  cutpoints = c(0, 0.001, 0.01, 0.05, 0.1, 1) 
  round_p = cut(p, cutpoints, labels=cutpoints[-1])
  p_value = paste0("$p < ", round_p, "$"  )

  paste(out1, p_value)
}
@

Which allows \Sexpr{trans(mycor)} to work as you want.