Added function to standardize a variable

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: cmdlr
 Type: Package
 Title: Choice Modeling in R
-Version: 0.0.4
+Version: 0.0.4.9001
 Authors@R: person("Erlend", "Dancke Sandorf", email = "erlend.dancke.sandorf@nmbu.no", role = c("aut", "cre"))
 Maintainer: Erlend Dancke Sandorf <erlend.dancke.sandorf@nmbu.no>
 Description: The problem of choice is fundamental to economics. Choice models are used to understand how people make choices in markets. cmdlR is a set of wrapper functions around a user written log-likelihood function. The package also contain several functions to check for local-optima, calculate welfare measures, compare results and make predictions. To get started, the package contains several examples with pre-programmed log-likelihood functions that can be easily tweaked by the user.

NAMESPACE

@@ -65,6 +65,7 @@ export(rep_rows)
 export(reshape_panel)
 export(save)
 export(search_start_values)
+export(standardize)
 export(subset_data)
 export(summary_poe_test)
 export(tidy)
@@ -94,4 +95,5 @@ importFrom(stats,coef)
 importFrom(stats,nobs)
 importFrom(stats,qnorm)
 importFrom(stats,runif)
+importFrom(stats,sd)
 importFrom(stats,vcov)

NEWS.md

@@ -1,3 +1,8 @@
+## cmdlr v0.0.5
+* Added a function to standardize variables 
+* General bug fixes
+
+
 ## cmdlr v0.0.4
 * Major structural changes to the code with multiple changes breaking existing code.
 * Code refactoring

R/cmdlR.R

@@ -18,7 +18,7 @@
 #' @docType package
 #' @name cmldr
 #' 
-#' @importFrom stats runif qnorm
+#' @importFrom stats runif qnorm sd
 #' @importFrom rlang sym := .data
 #' @importFrom dplyr bind_cols bind_rows n group_by starts_with
 #' @importFrom magrittr %>%

R/utils.R

@@ -101,3 +101,28 @@ load_packages <- function(pkgs) {
 
   return(NULL)
 }
+
+#' Standardize a variable
+#'
+#' Standardize a variable by subtracting the mean and dividing by the standard
+#' deviation
+#' 
+#' @param x A numeric vector
+#' @param na.rm A boolean equal to TRUE if ignore NA when calculating the mean
+#' and standard deviations. See \code{\link{mean}} and \code{\link{sd}}
+#'
+#' @examples
+#' x <- runif(10)
+#' standardize(x)
+#' 
+#' x[1] <- NA
+#' standardize(x, na.rm = TRUE)
+#' 
+#' @return A vector of standardized numbers
+#' 
+#' @export
+standardize <- function(x, na.rm = FALSE) {
+  return(
+    (x - mean(x, na.rm = na.rm)) / sd(x, na.rm = na.rm)
+  )
+}

tests/testthat/test-utils.R

@@ -21,3 +21,27 @@ test_that("Repeat columns correctly repeats the columns of a matrix", {
     )
   )
 })
+
+x <- runif(50)
+y <- c(runif(49), NA)
+
+test_that("Standardize works correctly", {
+  expect_equal(
+    standardize(x), standardize(x, na.rm = TRUE)
+  )
+
+  expect_equal(
+    mean(standardize(x)), 0
+  )
+
+  expect_equal(
+    sd(standardize(x)), 1
+  )
+
+  expect_equal(
+    mean(standardize(y)), mean(rep(NA, length(y)))
+  )
+
+  expect_true(all(is.numeric(standardize(y, na.rm = TRUE))))
+
+})