Elementwise map over one or more aligned rasters.

fn receives one traced array per input raster and returns one array; it runs fused with adjacent operations in one compiled kernel. Write it with plain arithmetic and the g_* vocabulary (g_ifelse(), g_bitand(), g_cast(), ...). Inputs must share a grid (align() first otherwise); rasters on different graphs merge automatically.

Usage

lazy_map(..., fn, dtype = NULL, bands = NULL)

Arguments

...

LazyRaster inputs (at least one), or a single LazyDataset.

fn

Function of as many arrays as there are inputs.

dtype

Optional output dtype override.

bands

LazyDataset only: bands to map over (default: all value bands).

Value

A LazyRaster, or a LazyDataset when given one.

Details

The output dtype defaults to the promoted input dtype; pass dtype when fn changes the value domain, e.g. "f32" for a mask that introduces NaN over an integer band.

Over a LazyDataset, fn is applied to every value band (a single dataset input only); bands restricts which bands, and non-selected bands pass through unchanged.

See also

collect()