Sum visits function & tests

R/globals.R

@@ -1 +1,3 @@
-utils::globalVariables(c("duration", "timestamp", "panelist_id","domain","visit","day","type","prev_type","tmp","session","host","suffix","domain_name","url_next", "host_next", "domain_next", "url_previous", "host_previous", "domain_previous"))
+utils::globalVariables(c("duration", "timestamp", "panelist_id","domain","visit","day","type","prev_type","tmp","session",
+                         "host","suffix","domain_name","url_next", "host_next", "domain_next", "url_previous", "host_previous", "domain_previous",
+                         "date", "week", "month", "year", "wave"))

R/summarize.R

@@ -0,0 +1,53 @@
+#' Summarize number of visits by person
+#' @description Summarize number of visits by person within a time frame, and optionally by class of visit
+#' @detail sum_visits allows you to summarize the number of visits by panelist_id for different time periods (for example, by day).
+#' It further allows to break down the number by any set of "classes" of visits, e.g. the type of the visit's domain.
+#' @param wt webtrack data object.
+#' @param timeframe character. indicates for what time frame to aggregate visits. Possible values are "date", "week", "month", "year", "wave" or "all".
+#' If set to "wave", webtrack data object must contain a column call "wave". Defaults to "all".
+#' @param visit_class character vector. Column(s) that contains a classification of visits.
+#' Visits will be grouped by values in this column before being summarized. Defaults to NULL.
+#' @importFrom data.table is.data.table shift .N
+#' @return a data.table with columns "panelist_id", column indicating the time unit unless "all" was specified,
+#' name indicating the class variable if specified, and "n_visits" indicating the number of visits
+#' @examples
+#' data("test_data")
+#' wt <- as.wt_dt(test_data)
+#' # example of visit classification
+#' wt <- extract_domain(wt)
+#' wt[,google:=ifelse(domain == "google.com", 1, 0)]
+#' wt[,search:=ifelse(grepl("search", url), 1, 0)]
+#' summary <- sum_visits(wt, timeframe = "month", visit_class = c("google", "search"))
+#' @export
+sum_visits <- function(wt, timeframe = "all", visit_class = NULL) {
+  stopifnot("input is not a wt_dt object" = is.wt_dt(wt))
+  vars_exist(wt,vars = c("url","panelist_id","timestamp"))
+  if (timeframe == "all") {
+    timeframe_var <- NULL
+  } else if (timeframe == "date") {
+    wt[, date := format(timestamp, format = "%F")]
+    timeframe_var <- "date"
+  } else if (timeframe == "week") {
+    wt[, week := format(timestamp, format = "%Y week %W")]
+    timeframe_var <- "week"
+  } else if (timeframe == "month") {
+    wt[, month := format(timestamp, format = "%Y month %m")]
+    timeframe_var <- "month"
+  } else if (timeframe == "year") {
+    wt[, year := format(timestamp, format = "%Y")]
+    timeframe_var <- "year"
+  } else if (timeframe == "wave") {
+    vars_wt <- names(wt)
+    wave <- pmatch("wave",vars_wt)
+    if (is.na(wave)) {
+      stop(paste0("couldn't find the column 'wave' in the webtrack data"), call. = FALSE)
+    } else {
+      timeframe_var <- "wave"
+    }
+  } else {
+    stop(paste0("unknown timeframe option specified"), call. = FALSE)
+  }
+  grp_vars <- c("panelist_id", timeframe_var, visit_class)
+  summary <- as.data.frame(wt[, list("n_visits" = .N), by = grp_vars])
+  summary[]
+}

tests/testthat/test-summarize.R

@@ -0,0 +1,23 @@
+test_that("sum_visits", {
+  data("test_data")
+  wt <- as.wt_dt(test_data)
+  wt <- extract_domain(wt)
+  wt[,google:=ifelse(domain == "google.com", 1, 0)]
+  wt[,search:=ifelse(grepl("search", url), 1, 0)]
+  wt_sum <- sum_visits(wt)
+  expect_true("n_visits" %in% names(wt_sum))
+  expect_true("panelist_id" %in% names(wt_sum))
+  # expect_true(sum_visits(wt), is.null(timeframe_var)) # this does not work, I assume because timeframe_var is not carried outside function
+  # also add other cases for timeframe_var
+  # check whether grouping variables in wt_sum
+})
+
+test_that("sum_visits errors", {
+  data("test_data")
+  wt <- as.wt_dt(test_data)
+  wt <- extract_domain(wt)
+  wt[,google:=ifelse(domain == "google.com", 1, 0)]
+  wt[,search:=ifelse(grepl("search", url), 1, 0)]
+  expect_error(sum_visits(wt, timeframe = "something"))
+  expect_error(sum_visits(wt, timeframe = "wave"))
+})