Columnar Query Engine for Larger-than-RAM Data

Documentation for package ‘vectra’ version 0.9.7

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-- A --

across	Apply a function across multiple columns
anti_join	Join two vectra tables
append_vtr	Append rows to an existing .vtr file
arrange	Sort rows by column values

-- B --

bind_cols	Bind rows or columns from multiple vectra tables
bind_rows	Bind rows or columns from multiple vectra tables
block_fuzzy_lookup	Fuzzy-match query keys against a materialized block
block_lookup	Probe a materialized block by column value

-- C --

chunk_feeder	Turn a query into a resettable chunk generator
collect	Execute a lazy query and return a data.frame
collect_chunked	Fold a function over a query, one batch at a time
collect_chunked.default	Fold a function over a query, one batch at a time
collect_chunked.vectra_node	Fold a function over a query, one batch at a time
collect_chunked.vectra_partition	Fold a function over a query, one batch at a time
collect_sf	Materialize a spatial query as an sf object
contours	Extract contour iso-lines from a streamed raster
count	Count observations by group
create_index	Create a hash index on a .vtr file column
cross_join	Cross join two vectra tables

-- D --

delete_vtr	Logically delete rows from a .vtr file
desc	Mark a column for descending sort order
diff_vtr	Compute the logical diff between two .vtr files
distinct	Keep distinct/unique rows

-- E --

explain

Print the execution plan for a vectra query

-- F --

filter	Filter rows of a vectra query
focal	Moving-window (focal) statistics over a streamed raster
full_join	Join two vectra tables
fuzzy_join	Fuzzy join two vectra tables by string distance

-- G --

geom_expressions	Geometry functions inside mutate(), filter(), and summarise()
glimpse	Get a glimpse of a vectra table
grid	Define a uniform grid for a partitioned spatial join
group_by	Group a vectra query by columns
group_map	Apply a function to each shard of a partition
group_map.vectra_partition	Apply a function to each shard of a partition
group_modify	Apply a function to each shard of a partition
group_modify.vectra_partition	Apply a function to each shard of a partition

-- H --

has_index	Check if a hash index exists for a .vtr column
head.vectra_node	Limit results to first n rows

-- I --

inner_join

Join two vectra tables

-- L --

left_join	Join two vectra tables
link	Define a link between a fact table and a dimension table
lookup	Look up columns from linked dimension tables

-- M --

mask	Mask a streamed raster to a polygon layer
materialize	Materialize a vectra node into a reusable in-memory block
mosaic	Merge aligned rasters onto a common grid
mutate	Add or transform columns

-- O --

offload

Spill a query to disk and stream it back (the offload functor)

-- P --

polygonize	Vectorise a raster into polygons
print.vectra_node	Print a vectra query node
proximity	Euclidean distance to the nearest feature (proximity)
pull	Extract a single column as a vector

-- R --

rasterize	Rasterize a streamed point layer onto a fixed grid
rast_calc	Cellwise calculation over aligned rasters (map algebra)
reframe	Summarise with variable-length output per group
relocate	Relocate columns
rename	Rename columns
right_join	Join two vectra tables

-- S --

select	Select columns from a vectra query
semi_join	Join two vectra tables
slice	Select rows by position
slice_head	Select first or last rows
slice_max	Select first or last rows
slice_min	Select first or last rows
slice_tail	Select first or last rows
spatial_centerline	Trace the centerline (medial axis) of streamed polygons
spatial_clip	Clip or erase a streamed layer against a resident mask
spatial_construct	Build a set-wise geometry construction, optionally per group
spatial_dissolve	Dissolve geometries by group
spatial_eliminate	Merge sliver polygons into a neighbour
spatial_explode	Explode multipart geometries into single-part features
spatial_filter	Keep streamed rows by their spatial relation to a resident layer
spatial_join	Spatial join a streamed query against a resident sf object
spatial_knn	k nearest neighbours of a streamed layer, with distances
spatial_line_merge	Merge contiguous line segments into maximal lines
spatial_locate	Locate streamed points along a resident line layer
spatial_map	Stream a query through an sf transform
spatial_network	Build a routable network graph from a line layer
spatial_overlay	Self-overlay a polygon layer into disjoint pieces (QGIS-style Union)
spatial_polygonize	Build polygonal faces from a line network
spatial_route	Shortest paths and origin-destination costs over a network
spatial_service_area	Service areas and isochrones over a network
spatial_simplify	Simplify a polygon coverage without tearing shared edges
spatial_smooth	Smooth streamed line and polygon geometry
spatial_snap	Snap a streamed layer toward a resident reference layer
spatial_snap_grid	Snap a streamed layer's coordinates to a fixed grid
spatial_split	Split a streamed layer by a resident blade, or return its crossing points
spatial_topology	Build the shared-edge topology of a polygon coverage
st_write.vectra_node	Stream a vectra node's geometry to a vector file
summarise	Summarise grouped data
summarize	Summarise grouped data

-- T --

tally	Count observations by group
tbl	Create a lazy table reference from a .vtr file
tbl_csv	Create a lazy table reference from a CSV file
tbl_sqlite	Create a lazy table reference from a SQLite database
tbl_tiff	Create a lazy table reference from a GeoTIFF raster
tbl_xlsx	Create a lazy table reference from an Excel (.xlsx) file
terrain	Terrain derivatives from a streamed elevation raster
tiff_band_names	Read per-band names from a GeoTIFF
tiff_crs	Read CRS metadata from a GeoTIFF
tiff_extract_points	Extract raster values at point coordinates
tiff_metadata	Read GDAL_METADATA from a GeoTIFF
transmute	Keep only columns from mutate expressions

-- U --

ungroup

Remove grouping from a vectra query

-- V --

vec_build_overviews	Build overview pyramids for a .vec raster
vec_close_raster	Close a .vec raster handle
vec_extract_points	Extract band values at (x, y) points from a .vec raster
vec_open_raster	Open a .vec raster
vec_raster_layout	Tile layout of an open .vec raster
vec_raster_times	Distinct time stamps stored in a .vec time cube
vec_read_pixel_series	Read the full time series at a single pixel from a .vec time cube
vec_read_time_slice	Read a single time slice from a .vec time cube
vec_read_window	Read a window of pixels from a .vec raster
vec_to_tiff	Export a .vec raster to GeoTIFF
vec_write_raster	Write a raster matrix or 3D array to a .vec raster file
vec_write_time_cube	Write a 4D time-cube raster to .vec
vtr_schema	Create a star schema over linked vectra tables

-- W --

warp	Resample or reproject a streamed raster onto a target grid
write_csv	Write query results or a data.frame to a CSV file
write_sqlite	Write query results or a data.frame to a SQLite table
write_tiff	Write query results to a GeoTIFF file
write_vtr	Write data to a .vtr file

-- Z --

zonal

Summarise raster values within zones