# Columnar Query Engine for Larger-than-RAM Data

## Documentation for package ‘vectra’ version 0.7.1

- DESCRIPTION file.
- User guides, package vignettes and other documentation.
- Package NEWS.

## Help Pages

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
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
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
count | Count observations by group
create_index | Create a hash index on a .vtr file column
cross_join | Cross join two vectra tables
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
explain | Print the execution plan for a vectra query
filter | Filter rows of a vectra query
full_join | Join two vectra tables
fuzzy_join | Fuzzy join two vectra tables by string distance
glimpse | Get a glimpse of a vectra table
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
has_index | Check if a hash index exists for a .vtr column
head.vectra_node | Limit results to first n rows
inner_join | Join two vectra tables
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
materialize | Materialize a vectra node into a reusable in-memory block
mutate | Add or transform columns
offload | Spill a query to disk and stream it back (the offload functor)
print.vectra_node | Print a vectra query node
pull | Extract a single column as a vector
reframe | Summarise with variable-length output per group
relocate | Relocate columns
rename | Rename columns
right_join | Join two vectra tables
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
summarise | Summarise grouped data
summarize | Summarise grouped data
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
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
ungroup | Remove grouping from a vectra query
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
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