Build the model design matrix

Reduces every attached layer to one row per management unit and season, which is the key the whole package is organised around.

Usage

build_features(
  p,
  aggregation = c("phenology", "monthly", "season"),
  stats = c("mean", "sum", "min", "max"),
  stress = TRUE,
  heat_threshold = 30,
  dry_threshold = 1
)

Arguments

p

An agri_project() with at least one layer attached. For aggregation = "phenology", phenology_windows() must have been run.

aggregation

How to group days within a season.

stats

Statistics to compute for each variable and group.

stress

Whether to derive stress-day counters.

heat_threshold

Daily maximum temperature, in degrees Celsius, above which a day counts as heat stress.

dry_threshold

Daily rainfall, in millimetres, below which a day counts as dry.

Value

The project, with features populated.

Details

Daily layers are aggregated within phenological stage by default, so that a feature such as prcp_sum_grain_fill carries the same meaning across sites that sowed weeks apart. Aggregating by calendar month instead is available for comparison, and is the usual practice in the literature; it is offered so the difference can be measured rather than assumed.

Stress counters are derived before aggregation: days above the heat threshold, days below freezing, dry days, and the longest dry spell in the season.

See also

phenology_windows(), check_project(), train_model()

Examples

p <- agri_project(demo_agri_data(n_units = 6, n_seasons = 2))
p <- add_climate(p, source = "demo")
p <- phenology_windows(p)
p <- build_features(p)
dim(p$features)
#> [1] 12 66