Computes logarithms in the server-side

Computes the logarithms for a specified numeric vector. This function is similar to the R log function. by default natural logarithms.

ds.log(x = NULL, base = exp(1), newobj = NULL, datasources = NULL)

Arguments

x

a character string providing the name of a numerical vector.

base

a positive number, the base for which logarithms are computed. Default exp(1).

newobj

a character string that provides the name for the output variable that is stored on the server-side. Default log.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.log returns a vector for each study of the transformed values for the numeric vector specified in the argument x. The created vectors are stored in the server-side.

Details

Server function called: log

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()
  
  # Log onto the remote Opal training servers
  connections <- DSI::datashield.login(logins = logindata, assign = TRUE, symbol = "D") 
  
  # Calculating the log value of the 'PM_BMI_CONTINUOUS' variable
  
  ds.log(x = "D$PM_BMI_CONTINUOUS",
         base = exp(2),
         newobj = "log.PM_BMI_CONTINUOUS",
         datasources = connections[1]) #only the first Opal server is used (study1)

  # clear the Datashield R sessions and logout
  datashield.logout(connections) 
} # }