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Summarize number of field-sampled polys and pixels by class and year

Source: R/fieldinfo.R
fieldinfo.Rd

Produces a table for site with subclass in the rows and year in the columns, and the number of 8 cm cells and the number of separate polys (in parentheses) in each cell, with row and column totals. There are two sources of field data, selected by onefile.

Usage

fieldinfo(
  site,
  onefile = TRUE,
  file = "C:/Work/saltmarsh/data/all_EPA_field/shapes_output.gpkg",
  buffer = 1
)

Arguments

site

Three letter site code

onefile

If TRUE, read raw field data for all sites from the GeoPackage file; if FALSE, use the site's transects.tif and transects shapefile

file

GeoPackage with raw field data for all sites, used when onefile = TRUE

buffer

Buffer radius in m for points and lines, and the distance lines are shortened at each end, used when onefile = TRUE

Details

With onefile = TRUE, field data for all sites come from a single GeoPackage (file) holding raw field geometry in three layers. As these data haven't been buffered, we do it here:

  • points are buffered by buffer, giving 2 m circles;

  • lines are shortened by buffer at each end and then buffered by buffer, giving 2 m wide transects with rounded ends that reach the ends of the original line. Lines too short to shorten collapse to their midpoint, giving a 2 m circle;

  • polygons are used as drawn.

Cell counts are then areas divided by the area of an 8 cm cell, so they're close but not exact: cells aren't actually laid on a grid, and overlapping polys are counted for each poly they fall in. Note that years are taken as given, unlike the onefile = FALSE case, which falls back on targetyear and uses year 0 for polys with no year at all.

With onefile = FALSE, data come from the site's rasterized field transects (transects.tif) and the site's transects shapefile, both built by gather, and cells are counted exactly.