Recodes the levels of a server-side factor vector

The function replaces the levels of a factor by the specified new ones.

ds.recodeLevels(
  x = NULL,
  newCategories = NULL,
  newobj = NULL,
  datasources = NULL
)

Arguments

x

a character string specifying the name of a factor variable.

newCategories

a character vector specifying the new levels. Its length must be equal or greater to the current number of levels.

newobj

a character string that provides the name for the output object that is stored on the data servers. Default recodelevels.newobj.

datasources

a list of DSConnection-class objects obtained after login. If the datasources argument is not specified the default set of connections will be used: see datashield.connections_default.

Value

ds.recodeLevels returns to the server-side a variable of type factor with the replaces levels.

Details

This function is similar to native R function levels().

It can for example be used to merge two classes into one, to add a level(s) to a vector or to rename (i.e. re-label) the levels of a vector.

Server function called: levels()

Author

DataSHIELD Development Team

Examples

if (FALSE) { # \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") 
  
  # Recode the levels of a factor variable
  
  ds.recodeLevels(x = "D$PM_BMI_CATEGORICAL",
                  newCategories = c("1","2","3"),
                  newobj = "BMI_CAT",
                  datasources = connections)
                 
  # Clear the Datashield R sessions and logout                 
  datashield.logout(connections) 
  
} # }