Extract Array Elements Safely — extract_array_element • Rduckhts

Helper function to safely extract elements from DuckDB arrays (returned as R lists) with proper error handling.

Usage

extract_array_element(array_col, index = NULL, default = NA)

Arguments

array_col: A list column from DuckDB array data
index: Numeric index (1-based). If NULL, returns full list
default: Default value if index is out of bounds

Value

The array element at the specified index, or full array if index is NULL

Examples

library(DBI)
library(duckdb)

con <- rduckhts_connect()
bcf_path <- system.file("extdata", "vcf_file.bcf", package = "Rduckhts")
rduckhts_bcf(con, "variants", bcf_path, overwrite = TRUE)
data <- dbGetQuery(con, "SELECT ALT FROM variants LIMIT 5")
first_alt <- extract_array_element(data$ALT, 1)
all_alts <- extract_array_element(data$ALT)
dbDisconnect(con, shutdown = TRUE)