ds.length {dsBaseClient} | R Documentation |
This function gets the length of a vector
or list that is stored on the server-side.
This function is similar to the R function length
.
ds.length(x = NULL, type = "both", checks = "FALSE", datasources = NULL)
x |
a character string specifying the name of a vector or list. |
type |
a character that represents the type of analysis to carry out.
If |
checks |
logical. If TRUE the model components are checked. Default FALSE to save time. It is suggested that checks should only be undertaken once the function call has failed. |
datasources |
a list of |
Server function called: lengthDS
ds.length
returns to the client-side the pooled length of a vector or a list,
or the length of a vector or a list for each study separately.
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$append(server = "study1", url = "http://192.168.56.100:8080/", user = "administrator", password = "datashield_test&", table = "CNSIM.CNSIM1", driver = "OpalDriver") builder$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") # Example 1: Get the total number of observations of the vector of # variable 'LAB_TSC' across all the studies ds.length(x = 'D$LAB_TSC', type = 'combine', datasources = connections) # Example 2: Get the number of observations of the vector of variable # 'LAB_TSC' for each study separately ds.length(x = 'D$LAB_TSC', type = 'split', datasources = connections) # Example 3: Get the number of observations on each study and the total # number of observations across all the studies for the variable 'LAB_TSC' ds.length(x = 'D$LAB_TSC', type = 'both', datasources = connections) # clear the Datashield R sessions and logout datashield.logout(connections) ## End(Not run)