Derive variables with TDA's expression language

Runs nvar on a data frame with new variables defined by TDA expressions, and returns the frame with them added. This is the way to the operators of the manual's 5.2.6 that have no R counterpart: the change and count operators (change, cntch), the aggregates over blocks (gcnt, grec, gmean, gstd, ...), TDA's random numbers, and so on.

Usage

tda_derive(data, ..., block = NULL, options = list(), dir = tempfile("tda"))

Arguments

data: a data frame.
...: named TDA expressions, as strings: CH = "change(S)".
block: a column name: with it, nvar runs in block mode (dblock=), and the block operators aggregate within blocks of consecutive rows with the same value.
options: a named list of further nvar options.
dir: working directory.

Value

data with the new columns, from the export channel.

Examples

d <- data.frame(ID = c(1, 1, 2), S = c(1, 3, 2))
tda_derive(d, CH = "change(S)", CN = "cntch(S)")
#>   ID S CH CN
#> 1  1 1  1  3
#> 2  1 3  1  3
#> 3  2 2  1  3
tda_derive(d, CN = "cntch(S)", block = "ID")
#>   ID S CN
#> 1  1 1  2
#> 2  1 3  2
#> 3  2 2  1