ds.names {dsBaseClient}

R Documentation

Return the names of a list object

Description

Returns the names of a designated server-side list

Usage

ds.names(xname = NULL, datasources = NULL)

Arguments

xname	a character string specifying the name of the list.
datasources	a list of DSConnection-class objects obtained after login that represent the particular data sources (studies) to be addressed by the function call. If the datasources argument is not specified the default set of connections will be used: see datashield.connections_default.

Details

ds.names calls aggregate function namesDS. This function is similar to the native R function names but it does not subsume all functionality, for example, it only works to extract names that already exist, not to create new names for objects. The function is restricted to objects of type list, but this includes objects that have a primary class other than list but which return TRUE to the native R function is.list. As an example this includes the multi-component object created by fitting a generalized linear model using ds.glmSLMA. The resultant object saved on each server separately is formally of class "glm" and "ls" but responds TRUE to is.list(),

Value

ds.names returns to the client-side the names of a list object stored on the server-side.

Author(s)

Amadou Gaye, updated by Paul Burton for DataSHIELD development team 25/06/2020

Examples

## Not run: 

 ## 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")
 
  #Create a list in the server-side
 
  ds.asList(x.name = "D",
            newobj = "D.list",
            datasources = connections)
           
  #Get the names of the list
 
  ds.names(xname = "D.list",
           datasources = connections)
 
 
  # clear the Datashield R sessions and logout
  datashield.logout(connections)


## End(Not run)

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