ds.exists | R Documentation |
Looks if an R object of the given name is defined on the server-side.
This function is similar to the R function exists
.
ds.exists(x = NULL, datasources = NULL)
x |
a character string providing the name of the object to look for. |
datasources |
a list of |
In DataSHIELD it is not possible to see the data on the servers of the collaborating studies. It is only possible to get summaries of objects stored on the server-side. It is however important to know if an object is defined (i.e. exists) on the server-side. This function checks if an object does exist on the server-side.
Server function called: exists
ds.exists
returns a logical object.
TRUE if the object is on the server-side and FALSE otherwise.
DataSHIELD Development Team
ds.class
to check the type of an object.
ds.length
to check the length of an object.
ds.dim
to check the dimension of an object.
## 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")
# Check if the object exist in the server-side
ds.exists(x = "D",
datasources = connections) #All opal servers are used
ds.exists(x = "D",
datasources = connections[1]) #Only the first Opal server is used (study1)
# clear the Datashield R sessions and logout
datashield.logout(connections)
## End(Not run)
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