ds.look | R Documentation |
The function ds.look
can be used to make a direct call to a server-side
aggregate function more simply than using the datashield.aggregate
function.
ds.look(toAggregate = NULL, checks = FALSE, datasources = NULL)
toAggregate |
a character string specifying the function call to be made. For more information see Details. |
checks |
logical. If TRUE the optional checks are undertaken. Default FALSE to save time. |
datasources |
a list of |
The ds.look
and datashield.aggregate
functions are generally
only recommended for experienced developers. For example, the toAggregate
argument has to
be expressed in the same form that the server-side function would usually expect from its
client-side pair. For example: ds.look("table1DDS(female)")
works. But, if you express
this as ds.look("table1DDS('female')")
it won't work because although when
you call this same function using its client-side function you write ds.table1D('female')
the inverted commas are stripped off during processing by the client-side function so the
call to the server-side does not contain inverted commas.
Apart from during development work (e.g. before a client-side function has been written) it is almost always easier and less error-prone to call a server-side function using its client-side pair.
The function is a wrapper for the DSI package function datashield.aggregate
.
the output from the specified server-side aggregate function to the client-side.
DataSHIELD Development Team
## 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$append(server = "study1",
url = "http://192.168.56.100:8080/",
user = "administrator", password = "datashield_test&",
table = "SURVIVAL.EXPAND_NO_MISSING1", driver = "OpalDriver")
builder$append(server = "study2",
url = "http://192.168.56.100:8080/",
user = "administrator", password = "datashield_test&",
table = "SURVIVAL.EXPAND_NO_MISSING2", driver = "OpalDriver")
builder$append(server = "study3",
url = "http://192.168.56.100:8080/",
user = "administrator", password = "datashield_test&",
table = "SURVIVAL.EXPAND_NO_MISSING3", driver = "OpalDriver")
logindata <- builder$build()
connections <- DSI::datashield.login(logins = logindata, assign = TRUE, symbol = "D")
#Calculate the length of a variable using the server-side function
ds.look(toAggregate = "lengthDS(D$age.60)",
checks = FALSE,
datasources = connections)
#Calculate the column names of "D" object using the server-side function
ds.look(toAggregate = "colnames(D)",
checks = FALSE,
datasources = connections)
# clear the Datashield R sessions and logout
datashield.logout(connections)
## End(Not run)
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