Included subsetHelper.R

Author: StuartWheater

R/subsetHelper.R

@@ -0,0 +1,76 @@
+#'
+#' @title Ensures that the requested subset is not larger than the original object
+#' @description Compares subset and original object sizes and eventually carries out subsetting. 
+#' @details This function is called by the function \code{ds.subset} to ensure that the requested subset
+#' is not larger than the original object.
+#' 
+#' This function is internal.
+#' 
+#' Server function called: \code{dimDS}
+#' @param dts a list of \code{\link[DSI]{DSConnection-class}} 
+#' objects obtained after login. If the \code{datasources} argument is not specified
+#' the default set of connections will be used: see \code{\link[DSI]{datashield.connections_default}}.
+#' @param data a character string specifying the name of the data frame or
+#' the factor vector and the range of the subset.
+#' @param rs a vector of two integers specifying the indices of the rows de extract.
+#' @param cs a vector of two integers or one or more characters.
+#' @keywords internal
+#' @return \code{subsetHelper} returns a message or the class of the object if the 
+#' object has the same class in all studies.
+#' @examples
+#' \dontrun{
+#'
+#'  ## Version 6, for version 5 see the Wiki
+#'   
+#'   # connecting to the Opal servers
+#' 
+#'   require('DSI')
+#'   require('DSOpal')
+#'   require('dsBaseClient')
+#'
+#'   builder <- DSI::newDSLoginBuilder()
+#'   builder$append(server = "study1", 
+#'                  url = "http://192.168.56.100:8080/", 
+#'                  user = "administrator", password = "datashield_test&", 
+#'                  table = "CNSIM.CNSIM1", driver = "OpalDriver")
+#'   builder$append(server = "study2", 
+#'                  url = "http://192.168.56.100:8080/", 
+#'                  user = "administrator", password = "datashield_test&", 
+#'                  table = "CNSIM.CNSIM2", driver = "OpalDriver")
+#'   builder$append(server = "study3",
+#'                  url = "http://192.168.56.100:8080/", 
+#'                  user = "administrator", password = "datashield_test&", 
+#'                  table = "CNSIM.CNSIM3", driver = "OpalDriver")
+#'   logindata <- builder$build()
+#'   
+#'   connections <- DSI::datashield.login(logins = logindata, assign = TRUE, symbol = "D")
+#'   
+#'   subsetHelper(dts = connections, 
+#'                data = "D", 
+#'                rs = 1:10, 
+#'                cs = c("D$LAB_TSC","D$LAB_TRIG"))  
+#'                       
+#'   # clear the Datashield R sessions and logout
+#'   datashield.logout(connections)
+#' }
+#'
+subsetHelper <- function(dts, data, rs=NULL, cs=NULL){
+
+  # if the size of the requested subset is greater than that of original inform the user and stop the process
+  dims <- DSI::datashield.aggregate(dts, call("dimDS", data))
+  fail <- c(0,0)
+
+  if(!(is.null(rs))){
+    if(length(rs) > dims[[1]][1] ){
+      fail[1] <- 1
+    }
+  }
+
+  if(!(is.null(cs))){
+    if(length(cs) > dims[[1]][2]){
+      fail[2] <- 1
+    }
+  }
+  return(fail)
+
+}