dssDeriveColumn: Add a calculated column to a dataframe

In IulianD/dsSwissKnifeClient: DataSHIELD Tools and Utilities - client side

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, length, as.Date, as.character, as.numeric. The administators 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)

Usage

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

Arguments

df	a character, the name of the dataframe
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
wait	same as in datashield.assign
new.col	a character, the name of the new column

Value

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

Examples

# open a local pseudo connection:
opals <- dssCreatePseudoServers(servers = 1, tie_first_to_GlobalEnv = TRUE)
data('iris')
#now play around:
dssDeriveColumn('iris', 'new_col', 'Sepal.Length/round(2.2)', datasources = opals)
str(iris)
dssDeriveColumn('iris', 'new_col2', 'iris$Sepal.Length/abs(-2)', datasources = opals)
str(iris)
a <- iris$Petal.Length
dssDeriveColumn('iris', 'new_col3', 'a/abs(-2)', datasources = opals)
str(iris)
# 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)

IulianD/dsSwissKnifeClient documentation built on June 23, 2020, 4:38 p.m.