Retrieve Environmental Data from Database

Queries environmental bottle cast data with temporal, depth, and variable filters. Returns a dbplyr lazy table for efficient downstream processing.

Usage

get_env(env_var, qtr, date_range, min_depth, max_depth)

Arguments

env_var: Character string of database column name for environmental variable (e.g., "t_deg_c", "salnty")
qtr: Character or numeric vector of quarters to include (1-4)
date_range: Date vector of length 2 (start date, end date)
min_depth: Numeric minimum depth in meters
max_depth: Numeric maximum depth in meters

Value

dbplyr lazy table with columns:

date - date of cast
time - time of cast (seconds since midnight)
dtime - datetime (computed via SQL CAST and INTERVAL)
depthm - depth in meters
lat_dec - latitude (decimal degrees)
lon_dec - longitude (decimal degrees)
qty - renamed environmental variable value
hex_h3res* - H3 hexagon indices at multiple resolutions

Details

The function joins cast and bottle tables, then joins with site to obtain H3 spatial indices. Only records with non-NA values for the selected variable are returned. Datetime is constructed from separate date and time fields using DuckDB SQL.

Examples

if (FALSE) { # \dontrun{
# retrieve temperature data for Q1-Q2 2010-2020
df_env <- get_env(
  env_var    = "t_deg_c",
  qtr        = c(1, 2),
  date_range = as.Date(c("2010-01-01", "2020-12-31")),
  min_depth  = 0,
  max_depth  = 100
)
df_env |> collect()
} # }