我试图构建一个修剪均值函数，但函数返回'NaN'，我不确定问题所在的函数

trimmed_mean <- function(x, trim) {
    n = length(x)
    ## the number to trim on each end
    n_to_trim = floor(trim * length(x))
    ## sort the vector
    x_sorted = sort(x)
    ## the indices of the elements to trim at the low end
    lo_idx = 1:n_to_trim
    ## the indices of the elements to trim at the high end
    hi_idx = (n - n_to_trim):n
    ## get rid of the lowest elements
    x_trimmed = x_sorted[!lo_idx]
    ## get rid of the highest elements
    x_trimmed = x_trimmed[!hi_idx]
    return(mean(x_trimmed))
}

## should give 2.75
trimmed_mean(c(-20, 1, 3, 2, 2, 5, 20, 2, 3, 4), trim = .1)

它应该返回2.75。