dssDeriveColumn: Add a calculated column to a dataframe

In sib-swiss/dsSwissKnifeClient: DataSHIELD Tools and Utilities - client side

Add a calculated column to a dataframe

Description

The new column is calculated from a formula that can contain arithmetic operators and a (very) limited number of R functions. At the moment the permitted functions are: abs, round, ceiling, floor, trunc, signif, paste0, length, as.Date, as.character, as.numeric, as.factor, gsub, grep,grepl, sqrt. The administrators of remote nodes can make more functions available with a procedure described in the help of the function .init in the package dsSwissKnife (?dsSwissKnife:::.init) There are two more functions available: 1) one.versus.others(col, positive.level) - this function reduces any factor to 2 levels in preparation for a logistic regression (see example below). 2) rnorm.0.1() creates a standard normal distribution in a new column. 3) nuke.outliers(col, maxval, minval) replaces all values in col that ar greater than maxval or smaller than minval with NAs

Usage

dssDeriveColumn(df, col.name, formula, datasources = NULL, async = TRUE)

Arguments

df	a character, the name of the dataframe
col.name	a character, the name of the new column
formula	a character, the formula used to calculate the new column. It can reference columns from the dataframe, or other objects in the session
datasources	same as in datashield.assign
async	same as in datashield.assign

Value

It doesn't return anything, the dataframe in the server session will now contain the new column.

Examples

# open a local pseudo connection:
library(DSLite)
dslite.server1 <<- newDSLiteServer(config = defaultDSConfiguration(include=c('dsSwissKnife')))
builder <- newDSLoginBuilder()
builder$append(server="server1", url='dslite.server1',driver = "DSLiteDriver")
logindata <- builder$build()
opals <- datashield.login(logins = logindata, assign = TRUE)
# load the iris dataset
datashield.aggregate(opals[1], as.symbol('partialData("iris")'))
#now play around:
dssDeriveColumn('iris', 'new_col', 'Sepal.Length/round(2.2)', datasources = opals)
str(pseudo_server$iris)
dssDeriveColumn('iris', 'new_col2', 'iris$Sepal.Length/abs(-2)', datasources = opals)
str(pseudo_server$iris)
a <- iris$Petal.Length
dssDeriveColumn('iris', 'new_col3', 'a/abs(-2)', datasources = opals)
str(pseudo_server$iris)
The built in function one.versus.others:
dssDeriveColumn('iris', 'new_col', 'one.versus.others(Species, "setosa")')
str(pseudo_server$iris$new_col)
#### ...Factor w/ 2 levels "setosa","no_setosa": 1 1 1 1 1 1 1 1 1 1 ...#
# this will fail:
dssDeriveColumn('iris', 'new_col', 'Sepal.Length[1]', datasources = opals)
# as will this
dssDeriveColumn('iris', 'new_col', 'rnorm(length(iris$Sepal.Length), mean = mean(iris$Sepal.Length),1)', datasources = opals)

sib-swiss/dsSwissKnifeClient documentation built on July 16, 2025, 6:25 p.m.