Generates a sequence in the server-side — ds.seq • dsBaseClient

This function generates a sequence for given parameters on the server-side.

ds.seq(
  FROM.value.char = "1",
  BY.value.char = "1",
  TO.value.char = NULL,
  LENGTH.OUT.value.char = NULL,
  ALONG.WITH.name = NULL,
  newobj = "newObj",
  datasources = NULL
)

Arguments

FROM.value.char: an integer or a number in character from specifying the starting value for the sequence. Default "1".
BY.value.char: an integer or a number in character from specifying the value to increment each step in the sequence. Default "1".
TO.value.char: an integer or a number in character from specifying the terminal value for the sequence. Default NULL. For more information see Details.
LENGTH.OUT.value.char: an integer or a number in character from specifying the length of the sequence at which point its extension should be stopped. Default NULL. For more information see Details.
ALONG.WITH.name: a character string specifying the name of a standard vector to generate a vector of the same length. For more information see Details.
newobj: a character string that provides the name for the output variable that is stored on the data servers. Default seq.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.seq returns to the server-side the generated sequence. Also, two validity messages are returned to the client-side indicating whether the new object has been created in each data source and if so whether it is in a valid form.

Details

This function is similar to a native R function seq(). It creates a flexible range of sequence vectors that can then be used to help manage and analyse data.

Note: the combinations of arguments that are not allowed for the function seq in native R are also prohibited in ds.seq.

To be specific, FROM.value.char argument defines the start of the sequence and BY.value.char defines how the sequence is incremented (or decremented) at each step. But where the sequence stops can be defined in three different ways:
(1) TO.value.char indicates the terminal value of the sequence. For example, ds.seq(FROM.value.char = "3", BY.value.char = "2", TO.value.char = "7") creates the sequence 3,5,7 on the server-side.
(2) LENGTH.OUT.value.char indicates the length of the sequence. For example, ds.seq(FROM.value.char = "3", BY.value.char = "2", LENGTH.OUT.value.char = "7") creates the sequence 3,5,7,9,11,13,15 on the server-side.
(3) ALONG.WITH.name specifies the name of a variable on the server-side, such that the sequence in each study will be equal in length to that variable. For example, ds.seq(FROM.value.char = "3", BY.value.char = "2", ALONG.WITH.name = "var.x") creates a sequence such that if var.x is of length 100 in study 1 the sequence written to study 1 will be 3,5,7,...,197,199,201 and if var.x is of length 4 in study 2, the sequence written to study 2 will be 3,5,7,9.
Only one of the three arguments: TO.value.char, LENGTH.OUT.value.char and ALONG.WITH.name can be non-null in any one call.

In LENGTH.OUT.value.char argument if you specify a number with a decimal point but in character form this result in a sequence length(integer) + 1. For example, LENGTH.OUT.value.char = "1000.0001" generates a sequence of length 1001.

Server function called: seqDS

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") 

  #Create 3 different sequences
  
  ds.seq(FROM.value.char = "1",
         BY.value.char = "2",
         TO.value.char = "7",
         newobj = "new.seq1",
         datasources = connections)
         
         
  ds.seq(FROM.value.char = "4",
         BY.value.char = "3",
         LENGTH.OUT.value.char = "10",
         newobj = "new.seq2",
         datasources = connections)  
         
  ds.seq(FROM.value.char = "2",
         BY.value.char = "5",
         ALONG.WITH.name = "D$GENDER",
         newobj = "new.seq3",
         datasources = connections)                            
         
  # Clear the Datashield R sessions and logout
  datashield.logout(connections) 
} # }