Creating a function that inputs data and outputs results in a list

Question

I am looking to create a function that take in data, perform a test, and then release the data to a list. The primary issue I'm having is how to get the list output to call from the previous if_else statement and say which type of test it is, and the summary of the tests. I'm pretty new to OOP, especially in R, so a little lost but here is what I have so far.

## Function
con_function <- function(x, y, alpha = 0.05) {
  if (var(x) == var(y)) {
    print(t.test(x, y, var.equal = TRUE))
  } else if (var(x) != var(y)) {
    print(t.test(x, y, var.equal = FALSE))
  }
  output_list <- list(data1 = x, data2 = y, # test_type = ?, reject_null =  ?,
  attr(output, "class") <- "example"

}

Answer 1

Your function can be simplified a bit. You can store the t test object and pull elements out of it with the $ operator

set.seed(47); x=rnorm(40,mean=18,sd=17)
set.seed(50); y=rnorm(40,mean=16,sd=17)

## Constructor Function
con_function <- function(x, y, alpha = 0.05) {
  
  tt <- t.test(x, y, var.equal = (var(x) == var(y)))

  structure(list(data1 = x, data2 = y, test = tt$method,
                 reject_null = tt$p.value < alpha), 
            class = "example")
}

con_function(x, y)
#> $data1
#>  [1]  51.909838  30.089423  21.151890  13.209995  19.849184  -0.457537
#>  [7]   1.246803  18.257225  13.715220  -6.917755   2.318244  18.673241
#> [13]  26.394943 -13.079896  19.555040  29.403247  16.621673  39.492099
#> [19]   6.042401  17.310171  -8.624755  22.235519  12.212928  25.092244
#> [25]  12.450065   2.865002  -9.338719 -21.480329 -15.442726  18.467956
#> [31]  26.221270  20.453740  -2.407491  33.048921  33.077896  18.011668
#> [37]   6.214965  22.434220  26.613678  27.593131
#> 
#> $data2
#>  [1]  25.344388   1.692736  16.560965  24.910545 -13.369270  11.276303
#>  [7]  22.134084   5.954488  32.585039  -8.577749  21.018515  25.430788
#> [13]   7.523196  19.327475   8.255811   9.831457  13.334172   2.990726
#> [19]  -3.822295  10.501763  10.051235   6.022749 -11.027920  44.722512
#> [25]  25.580922  61.349768  22.061094   9.843953  25.668688  16.487467
#> [31]  19.383398   1.525821  -3.217641  26.153232  -2.632814  16.324641
#> [37]  23.075383  47.274487  22.905172  22.684770
#> 
#> $test
#> [1] "Welch Two Sample t-test"
#> 
#> $reject_null
#> [1] FALSE
#> 
#> attr(,"class")
#> [1] "example"

^{Created on 2022-04-09 by the reprex package (v2.0.1)}