remove depencence on Kendall package

Author: vlyubchich

DESCRIPTION

@@ -1,8 +1,8 @@
 Package: funtimes
 Type: Package
 Title: Functions for Time Series Analysis
-Version: 9.2
-Date: 2023-04-28
+Version: 10.0
+Date: 2025-12-05
 Authors@R: c(person("Vyacheslav", "Lyubchich", 
                     role = c("aut", "cre"),
                     comment = c(ORCID = "0000-0001-7936-4285"),
@@ -19,7 +19,7 @@ Authors@R: c(person("Vyacheslav", "Lyubchich",
              person("Xingyu", "Wang", role = "ctb"))
 Depends: R (>= 3.5.0)
 License: GPL (>= 2)
-Imports: dbscan, Kendall, lmtest, mlVAR, parallel, Rdpack, sandwich, vars
+Imports: dbscan, lmtest, mlVAR, parallel, Rdpack, sandwich, vars
 Suggests: covid19us, Ecdat, ggplot2, gridExtra, knitr, patchwork, randomcoloR, readxl, reshape2, rmarkdown
 Description: Nonparametric estimators and tests for time series analysis. The functions use bootstrap techniques and robust nonparametric difference-based estimators to test for the presence of possibly non-monotonic trends and for synchronicity of trends in multiple time series.
 RdMacros: Rdpack

NAMESPACE

@@ -26,7 +26,6 @@ export(sync_test)
 export(tails_i)
 export(tails_q)
 export(wavk_test)
-importFrom(Kendall,MannKendall)
 importFrom(Rdpack,reprompt)
 importFrom(dbscan,dbscan)
 importFrom(grDevices,adjustcolor)

R/fun_cusum.R

@@ -8,6 +8,7 @@
 #   - Mfun(): Computes M(k1,...,km) statistic from p. 553
 #   - M1fun(): Optimized version for at most one changepoint
 #   - MTfun(): Computes MT statistic from p. 554 or first equation on p. 568
+#   - mann_kendall_tau(): Computes Kendall's tau for trend detection
 #
 # @keywords internal
 # @noRd

R/fun_trend.R

@@ -0,0 +1,26 @@
+# Internal Helper Functions for Trend Testing and Estimation
+#
+# This file contains internal (non-exported) helper functions for trend testing
+# and estimation methods. These functions are used by notrend_test(), wavk_test(),
+# sync_test(), and related trend analysis methods.
+#
+# Functions:
+#   - mann_kendall_tau(): Computes Kendall's tau for Mann-Kendall trend test
+#
+# @keywords internal
+# @noRd
+
+
+##### Mann-Kendall Trend Test Statistic #####
+# Internal implementation to replace Kendall::MannKendall() dependency
+# Computes Kendall's tau correlation between time series and time index
+#
+# @param x numeric vector (time series)
+# @return numeric scalar, Kendall's tau (from -1 to 1)
+mann_kendall_tau <- function(x) {
+    if (length(x) < 2) stop("The time series must have at least 2 observations")
+    
+    # Use base R's C-optimized cor() function
+    # Comparing 'x' against 'seq_along(x)' (time) is equivalent to Mann-Kendall
+    stats::cor(x, seq_along(x), method = "kendall")
+}

R/funtimes.R

@@ -32,7 +32,6 @@
 #' \insertAllCited{}
 #'
 #' @importFrom dbscan dbscan
-#' @importFrom Kendall MannKendall
 #' @importFrom Rdpack reprompt
 #' @importFrom stats acf ar arima arima0 arima.sim as.formula cov dist embed filter IQR lm loess median na.omit pnorm qnorm quantile rnorm sd var
 #' @importFrom utils combn

R/notrend_test.R

@@ -182,9 +182,9 @@ notrend_test <- function(x, B = 1000, test = c("t", "MK", "WAVK"),
     if (test == "MK") {
         METHOD <- "Sieve-bootstrap Mann--Kendall's trend test"
         ALTERNATIVE <- "monotonic trend."
-        STATISTIC <- MannKendall(x)$tau
+        STATISTIC <- mann_kendall_tau(x)
         names(STATISTIC) <- "Mann--Kendall's tau"
-        boot.stat <- sapply(1:dim(Y)[2], function(i) MannKendall(Y[,i])$tau)
+        boot.stat <- sapply(1:dim(Y)[2], function(i) mann_kendall_tau(Y[,i]))
     }
     #If WAVK test is used
     if (test == "WAVK") {

README.md

@@ -22,8 +22,12 @@ library(funtimes)
 
 ## Current GitHub version
 
+## CRAN version 10.0
+
 - Added new function `r_crit()` to compute critical values of correlations.
 - In the function `causality_pred()`, added option to turn off automatic lag selection. 
+- Removed defunct functions.
+- Removed dependence on the package `Kendall` by adding an internal helper function.
 
 ## CRAN version 9.1
 

funtimes.Rproj

@@ -18,4 +18,5 @@ BuildType: Package
 PackageUseDevtools: Yes
 PackageInstallArgs: --no-multiarch --with-keep.source
 PackageBuildBinaryArgs: --html
+PackageCheckArgs: --as-cran
 PackageRoxygenize: rd,collate,namespace,vignette