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LearnNonparam (version 1.3.0)

pmt: Syntactic Sugar for Object Construction

Description

Construct test objects in a unified way.

Usage

pmt(key, ...)

pmts( which = c("all", "onesample", "twosample", "distribution", "association", "paired", "ksample", "multcomp", "rcbd", "table") )

define_pmt( method = c("twosample", "distribution", "association", "paired", "ksample", "rcbd", "table"), statistic, rejection = c("<>", "<", "="">"), scoring = "none", n_permu = 10000, name = "User-Defined Permutation Test", alternative = NULL, quickr = FALSE, depends = character(), plugins = character(), includes = character() )

Value

a test object corresponding to the specified key.

a data frame containing keys and corresponding tests implemented in this package.

a test object based on the specified statistic.

Arguments

key

a character string specifying the test. Check pmts() for valid keys.

...

extra parameters passed to the constructor.

which

a character string specifying the desired tests.

method

a character string specifying the permutation scheme.

statistic

definition of the test statistic. See details.

rejection

a character string specifying the rejection region relative to the test statistic.

scoring

one of: - a character string in c("none", "rank", "vw", "expon") specifying the scoring system - a function that takes a numeric vector and returns an equal-length score vector

n_permu

an integer indicating number of permutations for the permutation distribution. If set to 0, all permutations will be used.

name, alternative

character strings specifying the name of the test and the alternative hypothesis, used for printing purposes only.

quickr

a logical indicating whether to use quickr::quick() to accelerate statistic. See details.

depends, plugins, includes

passed to Rcpp::cppFunction().

Details

The test statistic can be defined using either R or Rcpp, with the statistic parameter specified as:

  • R: a closure returning one of

    • a double (the test statistic).

    • a closure returning a double.

  • Rcpp: a character string defining a captureless lambda (since C++11) returning another lambda that captures by value, accepts parameters of the same type, and returns a double.

This design aims to pre-calculate potential constants that remain invariant during permutation.

When using Rcpp, the parameters for different method are listed as follows. Note that the names can be customized, and the types can be replaced with auto (thanks to the support for generic lambdas in C++14). See examples.

methodParameter 1Parameter 2
"twosample"const NumericVector& sample_1const NumericVector& sample_2
"distribution"const NumericVector& cumulative_prob_1const NumericVector& cumulative_prob_2
"association"const NumericVector& sample_1const NumericVector& sample_2
"paired"const NumericVector& sample_1const NumericVector& sample_2
"ksample"const NumericVector& combined_sampleconst IntegerVector& one_based_group_index
"rcbd"const NumericMatrix& block_as_column_data
"table"const IntegerMatrix& contingency_table

When using R, statistic and the parameters should be the R equivalents of the above. If no constants exist during permutation, statistic may simply be an R closure returning a double.

If quickr = TRUE and statistic returns a double, it will be compiled to Fortran via quickr::quick() with base::declare() calls for all arguments inserted automatically. Otherwise, statistic will be compiled using compiler::cmpfun().

Examples

Run this code
pmt("twosample.wilcoxon")

pmts("ksample")

x <- rnorm(5)
y <- rnorm(5, 1)

t <- define_pmt(
    method = "twosample", rejection = "<",
    scoring = base::rank, # equivalent to "rank"
    statistic = function(x, y) sum(x)
)$test(x, y)$print()

t$scoring <- function(x) qnorm(rank(x) / (length(x) + 1)) # equivalent to "vw"
t$print()

t$n_permu <- 0
t$print()

# \donttest{
r <- define_pmt(
    method = "twosample", n_permu = 1e5,
    statistic = function(x, y) {
        m <- length(x)
        n <- length(y)
        function(x, y) sum(x) / m - sum(y) / n
    }
)

quickr <- define_pmt(
    method = "twosample", n_permu = 1e5, quickr = TRUE,
    statistic = function(x, y) sum(x) / length(x) - sum(y) / length(y)
)

rcpp <- define_pmt(
    method = "twosample", n_permu = 1e5,
    statistic = "[](const auto& x, const auto& y) {
        auto m = x.length();
        auto n = y.length();
        return [=](const auto& x, const auto& y) {
            return sum(x) / m - sum(y) / n;
        };
    }"
)

# equivalent
# rcpp <- define_pmt(
#     method = "twosample", n_permu = 1e5,
#     statistic = "[](const NumericVector& x, const NumericVector& y) {
#         R_xlen_t m = x.length();
#         R_xlen_t n = y.length();
#         return [m, n](const NumericVector& x, const NumericVector& y) -> double {
#             return sum(x) / m - sum(y) / n;
#         };
#     }"
# )

set.seed(0)
r$test(x, y)$print()
set.seed(0)
quickr$test(x, y)$print()
set.seed(0)
rcpp$test(x, y)$print()

options(LearnNonparam.pmt_progress = FALSE)
system.time(r$test(x, y))
system.time(quickr$test(x, y))
system.time(rcpp$test(x, y))
# }

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