datashield.aggregate: Data aggregation

In DSI: 'DataSHIELD' Interface

Data aggregation

Description

Aggregates the expression result using the specified aggregation method in the current Datashield session.

Usage

datashield.aggregate(
  conns,
  expr,
  async = TRUE,
  success = NULL,
  error = NULL,
  errors.print = getOption("datashield.errors.print", FALSE)
)

Arguments

conns	DSConnection-class object or a list of DSConnection-classs.
expr	Expression to evaluate.
async	Whether the result of the call should be retrieved asynchronously. When TRUE (default) the calls are parallelized over the connections, when the connection supports that feature, with an extra overhead of requests.
success	Callback function that will be called each time an aggregation result is received from a connection. The expected function signature is the connection/study name and the result value. Default is NULL (no callback).
error	Callback function that will be called each time the aggregation request has failed. The expected function signature is the connection/study name and the error message. Default is NULL (no callback).
errors.print	Boolean, whether to print datashield errors in the console or return a message indicating that they can be retrieved using 'datashield.errors'.

Value

The result of the aggregation

Examples

## Not run: 
# call aggregate function on server side asynchronously
# i.e. each study connection will process the request in parallel
result <- datashield.aggregate(conns, expr = quote(someFunction(D, 123)))

# call aggregate function on server side synchronously, i.e. each study 
# connection will be called, one after the other, in a blocking way 
result <- datashield.aggregate(conns, expr = quote(someFunction(D, 123)), async = FALSE)

# call aggregate functions that are defined in the provided named list. 
# Connections are filtered by the list names.
result <- datashield.aggregate(conns,
  list(server1=quote(someFunction(D, 123)), server2=quote(someFunction(G, 456))))

# call aggregate function with callback functions
result <- datashield.aggregate(conns, expr = quote(someFunction(D, 123)),
  success = function(server, res) {
    # do something with server's result value
  },
  error = function(server, error) {
    # do something with server's error message
  })

## End(Not run)

DSI documentation built on Nov. 3, 2024, 9:08 a.m.