ds.length | 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)
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