diff --git a/DESCRIPTION b/DESCRIPTION
index 0699598dd1c5b68462fe88bc685decf6a3118831..82932749662559bc2486703db321dbabde0f3b4d 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -29,5 +29,6 @@ LazyData: true
 RoxygenNote: 5.0.0
 Suggests:
     knitr,
+    testthat,
     rmarkdown
 VignetteBuilder: knitr
diff --git a/NAMESPACE b/NAMESPACE
index e844fcba507d50c74a4134ac8da2afb5cc73769f..03fa0de4a2997108d8994eac872d50842c898dab 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -7,6 +7,7 @@ export(DTRIndicator)
 export(DTRRef)
 export(DailyAno)
 export(Extremes)
+export(Lon2Index)
 export(SeasonSelect)
 export(SelBox)
 export(Subset)
diff --git a/R/Climdex.R b/R/Climdex.R
index 261815c87202730a27012c9d64bc924017db340b..20c3e4301c453c1eb8fc7b41f9044298a415a9b7 100644
--- a/R/Climdex.R
+++ b/R/Climdex.R
@@ -373,7 +373,7 @@ Climdex <- function(data, metric, threshold = NULL, base.range = NULL, dates = N
 #' @noRd
 .nday.consec.prec.max <- function(daily.prec, date.factor, ndays, center.mean.on.last.day=FALSE) {
   if(ndays == 1) {
-    return(suppressWarnings(tapply.fast(daily.prec, date.factor, max, na.rm=TRUE)))
+    return(suppressWarnings(.tapply.fast(daily.prec, date.factor, max, na.rm=TRUE)))
   }
   ## Ends of the data will be de-emphasized (padded with zero precip data); NAs replaced with 0
   daily.prec[is.na(daily.prec)] <- 0
diff --git a/R/Extremes.R b/R/Extremes.R
index 30dd5698cd89eed9dd3bcfd445c98a4ec358229b..a60934044e546f29c5758e1b4f482c4fb75be81e 100644
--- a/R/Extremes.R
+++ b/R/Extremes.R
@@ -91,9 +91,9 @@ Extremes <- function(data, threshold, op = ">", min.length = 6, spells.can.span.
   if (!any(class(dates) %in% c('POSIXct'))) {
     dates <- try( {
       if (is.character(dates)) {
-        as.POSIXct(dates, format = "%Y%m%d")
+        as.POSIXct(dates, format = "%Y%m%d", tz = "CET")
       } else {
-        as.POSIXct(dates)
+        as.POSIXct(dates, format = "%Y%m%d", tz = "CET")
       }
     })
     if ('try-error' %in% class(dates) | sum(is.na(dates)) == length(dates)) {
@@ -113,8 +113,8 @@ Extremes <- function(data, threshold, op = ">", min.length = 6, spells.can.span.
   if (stop_error) {
     stop("Parameter 'dates' must be of the same length as the 'time' dimension of the parameter 'data'.")
   }
-  dates <- as.PCICt(dates, cal = calendar)
-  dates = as.character(dates)
+  dates <- as.PCICt(dates, cal = calendar, format = "%Y%m%d")
+#  dates = as.character(dates)
   jdays <- as.numeric(strftime(dates, format = "%j"))
   if (calendar == "gregorian" | calendar == "standard" | calendar == "proleptic_gregorian") {
     year <- as.numeric(strftime(dates, format = "%Y"))
diff --git a/R/Lon2Index.R b/R/Lon2Index.R
new file mode 100644
index 0000000000000000000000000000000000000000..1ab719714f75954d954e2a58cb9cea48ab9eb826
--- /dev/null
+++ b/R/Lon2Index.R
@@ -0,0 +1,87 @@
+#'Obtain the index of positions for a region in longitudes
+#'
+#'@description This auxiliary function returns the index of position of a region of longitudes in a given vector of longitudes.
+#'
+#'@param lon vector of longitudes values.
+#'@param lonmin a numeric value indicating the minimum longitude of the region (understand as the left marging of the region).
+#'@param lonmax a numeric value indicating the maximum longitude of the region (understand as the right mariging of the region).
+#'
+#'@return the index of positions of all values inside the region in the vector lon.
+#'
+#'@examples
+#'
+#'lon <- 1 : 360
+#'pos <- Lon2Index(lon, lonmin = -20, lonmax = 20)
+#'lon[pos]
+#'pos <- Lon2Index(lon, lonmin = 340, lonmax = 20)
+#'lon[pos]
+#'lon <- -180 : 180
+#'pos <- Lon2Index(lon, lonmin = -20, lonmax = 20)
+#'lon[pos]
+#'pos <- Lon2Index(lon, lonmin = 340, lonmax = 20)
+#'lon[pos]
+#'
+#'@export
+Lon2Index <- function(lon, lonmin, lonmax) {
+    if (is.null(lon)) {
+        stop("Parameter 'lon' cannot be NULL.")
+    }
+    if (!is.numeric(lon)) {
+        stop("Parameter 'lon' must be numeric.")
+    }
+    if (!is.vector(lon)) {
+        stop("Parameter 'lon' must be a vector.")
+    }
+    if (!is.numeric(lonmin) | !is.numeric(lonmax)) {
+        stop("Parameter 'lonmin' and 'lonmax' must be numeric.")
+    }
+    if (!is.vector(lonmin) | !is.vector(lonmax)) {
+        stop("Parameter 'lonmin'and 'lonmax' must be a vector.")
+    }
+
+    vlonmax <- max(lon)
+    vlonmin <- min(lon)
+    if (vlonmin < 0 & !(vlonmax > 180)) { # -180 to 180
+        if (lonmin < -180) {
+            stop("Change parameter 'lonmin' to match longitudes ",
+                 "in the range -180 to 180.")
+        } else if (lonmin > 180) {
+            lonmin <- lonmin - 360
+        } 
+        if (lonmax < -180) {
+            stop("Change parameter 'lonmax' to match longitudes ",
+                 "in the range -180 to 180.")
+        } else if (lonmax > 180) {
+            lonmax <- lonmax - 360
+        }
+        if (lonmin > lonmax) {
+            index <- c(which(lon >= lonmin), which(lon <= lonmax))  
+        } else {
+            index <- which(lon >= lonmin & lon <= lonmax)
+        }
+    } else if (vlonmin < 0 & vlonmax > 180) { # -360 to 360
+        if (lonmin > lonmax) {
+            index <- c(which(lon >= lonmin), which(lon <= lonmax))
+        } else {
+            index <- which(lon >= lonmin & lon <= lonmax)
+        }
+    } else { # 0 : 360
+        if (lonmin < 0) {
+            lonmin <- lonmin + 360
+        } else if (lonmin > 360) {
+            lonmin <- lonmin - 360
+        } 
+        if (lonmax < 0) {
+            lonmax <- lonmax + 360
+        } else if (lonmax > 360) {
+            lonmax <- lonmax - 360
+        }
+        if (lonmin > lonmax) {
+            index <- c(which(lon >= lonmin), which(lon <= lonmax))
+        } else {
+            index <- which(lon >= lonmin & lon <= lonmax)
+        }
+    }
+
+return(index)
+}
diff --git a/R/SelBox.R b/R/SelBox.R
index 608e19e0d65121960a1488765ed3f6b1f1d4ef98..5b7cd5982583f278142a8321c250539115676027 100644
--- a/R/SelBox.R
+++ b/R/SelBox.R
@@ -83,11 +83,13 @@ SelBox <- function(data, lon, lat, region, londim = NULL, latdim = NULL, mask =
   } else {
     LatIdx <- which(lat <= region[3] | lat >= region[4])
   }
-  if (region[1] <= region[2]) {
-    LonIdx <- which(lon >= region[1] & lon <= region[2])
-  } else {
-    LonIdx <- which(lon >= region[1] | lon <= region[2])
-  }
+  #if (region[1] <= region[2]) {
+  #  LonIdx <- which(lon >= region[1] & lon <= region[2])
+  #} else {
+  #  LonIdx <- which(lon >= region[1] | lon <= region[2])
+  #}
+  LonIdx <- Lon2Index(lon, lonmin = region[1], lonmax = region[2])
+
   data <- Subset(data, along = londim, indices = LonIdx, drop = "none")
   data <- Subset(data, along = latdim, indices = LatIdx, drop = "none")
   if (!is.null(mask)) {
diff --git a/man/Extremes.Rd b/man/Extremes.Rd
index 0939fa67275433b18b9f62df84150911ea72e352..61b312a1914f656ed97245920cfa4c447052e535 100644
--- a/man/Extremes.Rd
+++ b/man/Extremes.Rd
@@ -46,7 +46,8 @@ This routine compares data to the thresholds using the given operator, generatin
 ##Example synthetic data:
 data <- 1:(2 * 3 * 372 * 1)
 dim(data) <- c(time = 372, lon = 2, lat = 3, model = 1)
-time <- as.POSIXct(paste(sort(rep(1900:1911, 31)), 1, 1:31, sep = "-"), tz = "CET")
+time <- as.POSIXct(paste(sort(rep(1900:1911, 31)), 1, 1:31, sep = "-"), tz = "CET",
+                  format = "\%Y-\%m-\%d")
 metadata <- list(time = list(standard_name = 'time', long_name = 'time',  calendar = 'noleap', 
                             units = 'days since 1970-01-01 00:00:00', prec = 'double', 
                             dim = list(list(name = 'time', unlim = FALSE))))
diff --git a/man/Lon2Index.Rd b/man/Lon2Index.Rd
new file mode 100644
index 0000000000000000000000000000000000000000..b2012a61f97126ee886ba942f3e5020961d29994
--- /dev/null
+++ b/man/Lon2Index.Rd
@@ -0,0 +1,36 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/Lon2Index.R
+\name{Lon2Index}
+\alias{Lon2Index}
+\title{Obtain the index of positions for a region in longitudes}
+\usage{
+Lon2Index(lon, lonmin, lonmax)
+}
+\arguments{
+\item{lon}{vector of longitudes values.}
+
+\item{lonmin}{a numeric value indicating the minimum longitude of the region (understand as the left marging of the region).}
+
+\item{lonmax}{a numeric value indicating the maximum longitude of the region (understand as the right mariging of the region).}
+}
+\value{
+the index of positions of all values inside the region in the vector lon.
+}
+\description{
+This auxiliary function returns the index of position of a region of longitudes in a given vector of longitudes.
+}
+\examples{
+
+lon <- 1 : 360
+pos <- Lon2Index(lon, lonmin = -20, lonmax = 20)
+lon[pos]
+pos <- Lon2Index(lon, lonmin = 340, lonmax = 20)
+lon[pos]
+lon <- -180 : 180
+pos <- Lon2Index(lon, lonmin = -20, lonmax = 20)
+lon[pos]
+pos <- Lon2Index(lon, lonmin = 340, lonmax = 20)
+lon[pos]
+
+}
+
diff --git a/tests/testthat.R b/tests/testthat.R
new file mode 100644
index 0000000000000000000000000000000000000000..6b1f95fe7d2e17b7d026368643c5dd5ffb760f3e
--- /dev/null
+++ b/tests/testthat.R
@@ -0,0 +1,5 @@
+library(testthat)
+library(ClimProjDiags)
+
+test_check("ClimProjDiags")
+
diff --git a/tests/testthat/test-Lon2index.R b/tests/testthat/test-Lon2index.R
new file mode 100644
index 0000000000000000000000000000000000000000..8f530796f4911d759b3972a588fbcc265e59b763
--- /dev/null
+++ b/tests/testthat/test-Lon2index.R
@@ -0,0 +1,98 @@
+context("Generic tests")
+test_that("Sanity checks", {
+  expect_error(Lon2Index(lon = NULL), "Parameter 'lon' cannot be NULL.")
+  expect_error(Lon2Index(lon = 'a'), "Parameter 'lon' must be numeric.")
+  expect_error(Lon2Index(lon = 1),
+               'argument "lonmin" is missing, with no default')
+  expect_error(Lon2Index(lon = 1, lonmin = 'a'),
+               'argument "lonmax" is missing, with no default')
+  expect_error(Lon2Index(lon = 1, lonmin = 'a', lonmax = 1),
+               "Parameter 'lonmin' and 'lonmax' must be numeric.")
+  expect_error(Lon2Index(lon = 1, lonmin = 1, lonmax = 'b'),
+               "Parameter 'lonmin' and 'lonmax' must be numeric.")
+  expect_equal(Lon2Index(lon = 1, lonmin = 1, lonmax = 1), 1)
+})
+
+test_that("Case 1 to 360", {
+lon <- 1 : 360
+  expect_equal(Lon2Index(lon, lonmin = -20, lonmax = 20),
+               c(340 : 360, 1 : 20))
+  expect_equal(Lon2Index(lon, lonmin = 340, lonmax = 20),
+               c(340 : 360, 1 : 20))
+  expect_equal(Lon2Index(lon, lonmin = 20, lonmax = 340),
+               20 : 340)
+  expect_equal(Lon2Index(lon, lonmin = -40, lonmax = -20),
+               320 : 340)
+  expect_equal(Lon2Index(lon, lonmin = 320, lonmax = 340),
+               320 : 340)
+  expect_equal(Lon2Index(lon, lonmin = -220, lonmax = -170),
+               140 : 190)
+  expect_equal(Lon2Index(lon, lonmin = -350, lonmax = -300),
+               10 : 60)
+  expect_equal(Lon2Index(lon, lonmin = -400, lonmax = -370), integer(0))
+  expect_equal(Lon2Index(lon, lonmin = 340, lonmax = 380),
+               c(340 : 360, 1 : 20))
+})
+
+test_that("Case -180 to 180", {
+lon <- -180 : 180
+  expect_equal(Lon2Index(lon, lonmin = -20, lonmax = 20),
+               161 : 201)
+  expect_equal(Lon2Index(lon, lonmin = 340, lonmax = 20),
+               161 : 201)
+  expect_equal(Lon2Index(lon, lonmin = 20, lonmax = 340),
+               c(201 : 361, 1 : 161))
+  expect_equal(Lon2Index(lon, lonmin = -40, lonmax = -20),
+               141 : 161)
+  expect_equal(Lon2Index(lon, lonmin = 320, lonmax = 340),
+               141 : 161)
+  expect_error(Lon2Index(lon, lonmin = -220, lonmax = -170),
+        "Change parameter 'lonmin' to match longitudes in the range -180 to 180.")
+  expect_error(Lon2Index(lon, lonmin = -350, lonmax = -300),
+        "Change parameter 'lonmin' to match longitudes in the range -180 to 180.")
+  expect_error(Lon2Index(lon, lonmin = -400, lonmax = -370),
+        "Change parameter 'lonmin' to match longitudes in the range -180 to 180.")
+  expect_equal(Lon2Index(lon, lonmin = 340, lonmax = 380),
+               161 : 201)
+})
+
+test_that("Case -360 to 360", {
+lon <- -360 : 360
+  expect_equal(Lon2Index(lon, lonmin = -20, lonmax = 20),
+               341 : 381)
+  expect_equal(Lon2Index(lon, lonmin = 340, lonmax = 20),
+               c(701 : 721, 1 : 381))
+  expect_equal(Lon2Index(lon, lonmin = 20, lonmax = 340),
+               381 : 701)
+  expect_equal(Lon2Index(lon, lonmin = -40, lonmax = -20),
+               321 : 341)
+  expect_equal(Lon2Index(lon, lonmin = 320, lonmax = 340),
+               681 : 701)
+  expect_equal(Lon2Index(lon, lonmin = -220, lonmax = -170),
+               141 : 191)
+  expect_equal(Lon2Index(lon, lonmin = -350, lonmax = -300),
+               11 : 61)
+  expect_equal(Lon2Index(lon, lonmin = -400, lonmax = -370), integer(0))
+  expect_equal(Lon2Index(lon, lonmin = 340, lonmax = 380),
+               701 : 721)
+})
+
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