Introduce initialization function

sma_init() can now be used to load all libraries and the data.
It is safe to call sma_init() multiple times. To forcefully reload the
data call sma_init_force().

survival.R

@@ -3,11 +3,8 @@
 # License: GPL version 3
 # Jens Mathis Sauer (c) 2020
 
-library(survival)
-library(survminer)
 source("utils.R")
-
-secmal <- sma_load_data("current.csv")
+sma_init()
 
 # Setup survival object
 surv_dx <- Surv(time = secmal$event_time_dx, event = secmal$event_status)

utils.R

@@ -3,8 +3,6 @@
 # License: GPL version 3
 # Jens Mathis Sauer (c) 2020
 
-library(tidyverse)
-
 #
 # Write plot to filename
 #
@@ -86,3 +84,40 @@ sma_load_data <- function(file) {
 # Global break.time.by value
 #
 sma_break.time.by = 5 * 365.25
+
+#
+# Initialize secMalASCT workspace
+#
+# This function can be called multiple times, the data will only
+# be loaded once. To manually reload data call:
+# > sma_init_force()
+#
+sma_init <- function() {
+	if (exists("sma_initialized") == FALSE) {
+		print("Initialize secMalASCT workspace")
+
+		print("Loading libraries")
+		library(survival)
+		library(survminer)
+		library(tidyverse)
+
+		print("Loading data")
+		#
+		# Use superassignment operator '<<-' to make
+		# secmal and sma_initialized with global scope.
+		#
+		secmal <<- sma_load_data("current.csv")
+		sma_initialized <<- TRUE
+	}
+}
+
+#
+# Force reinitialization of workspace
+#
+# Forcefully calls sma_init() again.
+#
+sma_init_force <- function() {
+	print("Reloading secMalASCT data")
+	remove(sma_initialized, pos = ".GlobalEnv")
+	sma_init()
+}