Computes the square root values of a variable

Computes the square root values for a specified numeric or integer vector. This function is similar to R function sqrt.

ds.sqrt(x = NULL, newobj = NULL, datasources = NULL)

Arguments

x

a character string providing the name of a numeric or an integer vector.

newobj

a character string that provides the name for the output variable that is stored on the data servers. Default name is set to sqrt.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.sqrt assigns a vector for each study that includes the square root values of the input numeric or integer vector specified in the argument x. The created vectors are stored in the servers.

Details

The function calls the server-side function sqrtDS that computes the square root values of the elements of a numeric or integer vector and assigns a new vector with those square root values on the server-side. The name of the new generated vector is specified by the user through the argument newobj, otherwise is named by default to sqrt.newobj.

Author

Demetris Avraam for DataSHIELD Development Team

Examples

if (FALSE) { # \dontrun{

  # 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") 
  
  # Example 1: Get the square root of LAB_HDL variable
  ds.sqrt(x='D$LAB_HDL', newobj='LAB_HDL.sqrt', datasources=connections)
  # compare the mean of LAB_HDL and of LAB_HDL.sqrt
  # Note here that the number of missing values is bigger in the LAB_HDL.sqrt 
  ds.mean(x='D$LAB_HDL', datasources=connections)
  ds.mean(x='LAB_HDL.sqrt', datasources=connections)

  # Example 2: Generate a repeated vector of the squares of integers from 1 to 10
  # and get their square roots
  ds.make(toAssign='rep((1:10)^2, times=10)', newobj='squares.vector', datasources=connections)
  ds.sqrt(x='squares.vector', newobj='sqrt.vector', datasources=connections)
  # check the behavior of that operation by comparing the tables of squares.vector and sqrt.vector
  ds.table(rvar='squares.vector')$output.list$TABLE_rvar.by.study_counts
  ds.table(rvar='sqrt.vector')$output.list$TABLE_rvar.by.study_counts

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

} # }