Is there any way to control the output decimal places of the t-test function?

Question

I'm using the built-in t-test function.

Code below:

t.test(
  mpg$cyl[mpg$model == "a4"],
  drill_df$Time_hr[mpg$model == "malibu"],
  alternative = "l",
  mu = 0,
  conf.level = 0.95,
)

Answer 1

Here is a solution. Write a function t_test calling t.test and then round the numbers in a lapply loop. The return value of lapply is a list, so class "htest" must be assigned manually before returning to caller.

t_test <- function(..., d = 2){
  tt <- t.test(...)
  tt <- lapply(tt, function(x){
    if(is.numeric(x)) round(x, d) else x
  })
  class(tt) <- "htest"
  tt
}

t_test(
  mpg$cyl[mpg$model == "a4"],
  mpg$cyl[mpg$model == "malibu"],
  alternative = "l",
  mu = 0,
  conf.level = 0.95,
)
#   Welch Two Sample t-test
#
#data:  mpg$cyl[mpg$model == "a4"] and mpg$cyl[mpg$model == "malibu"]
#t = -0.54, df = 8.63, p-value = 0.3
#alternative hypothesis: true difference in means is less than 0
#95 percent confidence interval:
# -Inf 0.83
#sample estimates:
#mean of x mean of y 
#     4.86      5.20