Title:	Columnar Query Engine for Larger-than-RAM Data
Version:	0.5.1
Description:	A minimal columnar query engine with lazy execution on datasets larger than RAM. Provides 'dplyr'-like verbs (filter(), select(), mutate(), group_by(), summarise(), joins, window functions) and common aggregations (n(), sum(), mean(), min(), max(), sd(), first(), last()) backed by a pure C11 pull-based execution engine and a custom on-disk format ('.vtr').
License:	MIT + file LICENSE
Depends:	R (≥ 4.1.0)
SystemRequirements:	GNU make
Encoding:	UTF-8
Imports:	tidyselect, rlang
RoxygenNote:	7.3.3
Suggests:	bit64, knitr, openxlsx2, rmarkdown, testthat (≥ 3.0.0)
VignetteBuilder:	knitr
Config/testthat/edition:	3
URL:	https://gillescolling.com/vectra/, https://github.com/gcol33/vectra
BugReports:	https://github.com/gcol33/vectra/issues
NeedsCompilation:	yes
Packaged:	2026-04-20 09:16:33 UTC; Gilles Colling
Author:	Gilles Colling [aut, cre, cph]
Maintainer:	Gilles Colling <gilles.colling051@gmail.com>
Repository:	CRAN
Date/Publication:	2026-04-21 20:00:02 UTC

Apply a function across multiple columns

Description

Used inside mutate() or summarise() to apply a function to multiple columns selected with tidyselect. Returns a named list of expressions.

Usage

across(.cols, .fns, ..., .names = NULL)

Arguments

Value

A named list used internally by mutate/summarise.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
# In summarise (conceptual; across is expanded to individual expressions)
unlink(f)

Append rows to an existing .vtr file

Description

Appends one or more new row groups to the end of an existing .vtr file without touching or recompressing existing row groups. The schema of x must exactly match the schema of the target file (same column names and types, in the same order).

Usage

append_vtr(x, path, ...)

Arguments

Details

The operation is not fully atomic: if the process is interrupted after new row groups are written but before the header is patched, the file will be in a corrupted state. Use write_vtr() for safety-critical write-once workloads.

Value

Invisible NULL.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars[1:10, ], f)
append_vtr(mtcars[11:20, ], f)
result <- tbl(f) |> collect()
stopifnot(nrow(result) == 20L)
unlink(f)

Sort rows by column values

Description

Sort rows by column values

Usage

arrange(.data, ...)

Arguments

Details

Uses an external merge sort with a 1 GB memory budget. When data exceeds this limit, sorted runs are spilled to temporary .vtr files and merged via a k-way min-heap. NAs sort last in ascending order.

This is a materializing operation.

Value

A new vectra_node with sorted rows.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> arrange(desc(mpg)) |> collect() |> head()
unlink(f)

Bind rows or columns from multiple vectra tables

Description

Bind rows or columns from multiple vectra tables

Usage

bind_rows(..., .id = NULL)

bind_cols(...)

Arguments

Details

When all inputs are vectra_node objects with identical column names and types and no .id is requested, bind_rows creates a streaming ConcatNode that iterates children sequentially without materializing.

Otherwise, inputs are collected and combined in R. Missing columns are filled with NA.

bind_cols requires the same number of rows in each input.

Value

A vectra_node (streaming) when all inputs are vectra_node with identical schemas and .id is NULL. Otherwise a data.frame.

Examples

f1 <- tempfile(fileext = ".vtr")
f2 <- tempfile(fileext = ".vtr")
write_vtr(data.frame(x = 1:3, y = 4:6), f1)
write_vtr(data.frame(x = 7:9, y = 10:12), f2)
bind_rows(tbl(f1), tbl(f2)) |> collect()
bind_cols(tbl(f1), tbl(f2))
unlink(c(f1, f2))

Fuzzy-match query keys against a materialized block

Description

Computes string distances between query keys and a string column in a materialized block. Optionally uses exact-match blocking on a second column (e.g., genus) to reduce the search space.

Usage

block_fuzzy_lookup(
  block,
  column,
  keys,
  method = "dl",
  max_dist = 0.2,
  block_col = NULL,
  block_keys = NULL,
  n_threads = 4L
)

Arguments

Value

A data.frame with columns query_idx (1-based position in keys), fuzzy_dist (normalized distance), plus all columns from the block.

Probe a materialized block by column value

Description

Performs a hash lookup on a string column of a materialized block. Returns all rows where the column value matches one of the query keys. Hash indices are built lazily on first use and cached for subsequent calls.

Usage

block_lookup(block, column, keys, ci = FALSE)

Arguments

Value

A data.frame with column query_idx (1-based position in keys) plus all columns from the block, for each (query, block_row) match pair.

Examples

f <- tempfile(fileext = ".vtr")
df <- data.frame(taxonID = 1:2,
                 canonicalName = c("Quercus robur", "Pinus sylvestris"))
write_vtr(df, f)
blk <- materialize(tbl(f))
hits <- block_lookup(blk, "canonicalName", c("Quercus robur"))
ci_hits <- block_lookup(blk, "canonicalName", c("quercus robur"), ci = TRUE)
unlink(f)

Execute a lazy query and return a data.frame

Description

Pulls all batches from the execution plan and materializes the result as an R data.frame.

Usage

collect(x, ...)

Arguments

Value

A data.frame with the query results.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
result <- tbl(f) |> collect()
head(result)
unlink(f)

Count observations by group

Description

Count observations by group

Usage

count(x, ..., wt = NULL, sort = FALSE, name = NULL)

tally(x, wt = NULL, sort = FALSE, name = NULL)

Arguments

Details

Equivalent to group_by(...) |> summarise(n = n()). When wt is provided, uses sum(wt) instead of n(). When sort = TRUE, results are sorted in descending order of the count column.

Value

A vectra_node with group columns and a count column.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> count(cyl) |> collect()
unlink(f)

Create a hash index on a .vtr file column

Description

Builds a persistent hash index stored as a .vtri sidecar file alongside the .vtr file. The index maps key hashes to row group indices, enabling O(1) row group identification for equality predicates (filter(col == value)).

Usage

create_index(path, column, ci = FALSE)

Arguments

Details

For composite indexes on multiple columns, pass a character vector. Composite indexes accelerate AND-combined equality predicates (e.g., filter(col1 == "a", col2 == "b")).

The index is automatically loaded by tbl() when present. It composes with zone-map pruning and binary search on sorted columns.

Value

Invisible NULL. The index is written as a .vtri sidecar file.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(data.frame(id = letters, val = 1:26, stringsAsFactors = FALSE), f)
create_index(f, "id")
tbl(f) |> filter(id == "m") |> collect()
unlink(c(f, paste0(f, ".id.vtri")))

Cross join two vectra tables

Description

Returns every combination of rows from x and y (Cartesian product). Both tables are collected before joining.

Usage

cross_join(x, y, suffix = c(".x", ".y"), ...)

Arguments

Value

A data.frame with nrow(x) * nrow(y) rows.

Examples

f1 <- tempfile(fileext = ".vtr")
f2 <- tempfile(fileext = ".vtr")
write_vtr(data.frame(a = 1:2), f1)
write_vtr(data.frame(b = c("x", "y", "z"), stringsAsFactors = FALSE), f2)
cross_join(tbl(f1), tbl(f2))
unlink(c(f1, f2))

Logically delete rows from a .vtr file

Description

Marks the specified 0-based physical row indices as deleted by writing (or updating) a tombstone side file (⁠<path>.del⁠). The original .vtr file is never modified. The next call to tbl() on the same path will automatically exclude the deleted rows.

Usage

delete_vtr(path, row_ids)

Arguments

Details

Tombstone files are cumulative: calling delete_vtr() multiple times on the same file merges all deletions (union, deduplicated). To undo deletions, remove the .del file manually with unlink(paste0(path, ".del")).

Value

Invisible NULL.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)

# Delete the first and third rows (0-based indices 0 and 2)
delete_vtr(f, c(0, 2))

result <- tbl(f) |> collect()
stopifnot(nrow(result) == nrow(mtcars) - 2L)

unlink(c(f, paste0(f, ".del")))

Mark a column for descending sort order

Description

Used inside arrange() to sort a column in descending order.

Usage

desc(x)

Arguments

Value

A marker used by arrange().

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> arrange(desc(mpg)) |> collect() |> head()
unlink(f)

Compute the logical diff between two .vtr files

Description

Streams both files and computes a set-level diff keyed on key_col. Returns a list with two elements:

Usage

diff_vtr(old_path, new_path, key_col)

Arguments

Details

• added: a vectra_node (lazy tbl()) of rows present in new_path but not old_path (matched on key_col). Call collect() to materialise. The underlying temp file is deleted when the node is garbage-collected or when the calling R session ends via on.exit().

• deleted: a vector of key values present in old_path but not new_path.

This is a logical diff (key-based set difference), not a binary file diff. Rows with the same key that have changed values are not reported as modified — use added and deleted together to detect updates (a key that appears in both means a row was replaced).

Value

A named list with elements added (a vectra_node) and deleted (a vector of key values).

Examples

f1 <- tempfile(fileext = ".vtr")
f2 <- tempfile(fileext = ".vtr")
df1 <- data.frame(id = 1:5, val = letters[1:5], stringsAsFactors = FALSE)
df2 <- data.frame(id = c(3L, 4L, 5L, 6L, 7L),
                  val = c("C", "d", "e", "f", "g"),
                  stringsAsFactors = FALSE)
write_vtr(df1, f1)
write_vtr(df2, f2)

d <- diff_vtr(f1, f2, "id")
# Rows 1 and 2 deleted; rows 6 and 7 added
stopifnot(all(d$deleted %in% c(1, 2)))
stopifnot(all(collect(d$added)$id %in% c(6, 7)))

unlink(c(f1, f2))

Keep distinct/unique rows

Description

Keep distinct/unique rows

Usage

distinct(.data, ..., .keep_all = FALSE)

Arguments

Details

Uses hash-based grouping with zero aggregations. When .keep_all = TRUE with a column subset, falls back to R's duplicated() with a message.

This is a materializing operation.

Value

A vectra_node with unique rows.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> distinct(cyl) |> collect()
unlink(f)

Print the execution plan for a vectra query

Description

Shows the node types, column schemas, and structure of the lazy query plan.

Usage

explain(x, ...)

Arguments

Value

Invisible x.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> filter(cyl > 4) |> select(mpg, cyl) |> explain()
unlink(f)

Filter rows of a vectra query

Description

Filter rows of a vectra query

Usage

filter(.data, ...)

Arguments

Details

Filter uses zero-copy selection vectors: matching rows are indexed without copying data. Multiple conditions are combined with &. Supported expression types: arithmetic (+, -, *, /, %%), comparison (==, !=, <, <=, >, >=), boolean (&, |, !), is.na(), and string functions (nchar(), substr(), grepl() with fixed patterns).

NA comparisons return NA (SQL semantics). Use is.na() to filter NAs explicitly.

This is a streaming operation (constant memory per batch).

Value

A new vectra_node with the filter applied.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> filter(cyl > 4) |> collect() |> head()
unlink(f)

Fuzzy join two vectra tables by string distance

Description

Joins two tables using approximate string matching on key columns. Optionally blocks by a second column (e.g., genus) for performance — only rows sharing the same blocking key are compared.

Usage

fuzzy_join(
  x,
  y,
  by,
  method = "dl",
  max_dist = 0.2,
  block_by = NULL,
  n_threads = 4L,
  suffix = ".y"
)

Arguments

Value

A vectra_node with all probe columns, all build columns (suffixed on collision), and a fuzzy_dist column (double).

Get a glimpse of a vectra table

Description

Shows column names, types, and a preview of the first few values without collecting the full result.

Usage

glimpse(x, width = 5L, ...)

Arguments

Value

Invisible x.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> glimpse()
unlink(f)

Group a vectra query by columns

Description

Group a vectra query by columns

Usage

group_by(.data, ...)

Arguments

Value

A vectra_node with grouping information stored.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> group_by(cyl) |> summarise(avg = mean(mpg)) |> collect()
unlink(f)

Check if a hash index exists for a .vtr column

Description

Check if a hash index exists for a .vtr column

Usage

has_index(path, column)

Arguments

Value

Logical scalar: TRUE if a .vtri index file exists.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(data.frame(id = letters, val = 1:26, stringsAsFactors = FALSE), f)
has_index(f, "id")   # FALSE
create_index(f, "id")
has_index(f, "id")   # TRUE
unlink(c(f, paste0(f, ".id.vtri")))

Limit results to first n rows

Description

Limit results to first n rows

Usage

## S3 method for class 'vectra_node'
head(x, n = 6L, ...)

Arguments

Value

A data.frame with the first n rows.

Join two vectra tables

Description

Join two vectra tables

Usage

left_join(x, y, by = NULL, suffix = c(".x", ".y"), ...)

inner_join(x, y, by = NULL, suffix = c(".x", ".y"), ...)

right_join(x, y, by = NULL, suffix = c(".x", ".y"), ...)

full_join(x, y, by = NULL, suffix = c(".x", ".y"), ...)

semi_join(x, y, by = NULL, ...)

anti_join(x, y, by = NULL, ...)

Arguments

Details

All joins use a build-right, probe-left hash join. The entire right-side table is materialized into a hash table; left-side batches stream through. Memory cost is proportional to the right-side table size.

NA keys never match (SQL NULL semantics). Key types are auto-coerced following the ⁠bool < int64 < double⁠ hierarchy. Joining string against numeric keys is an error.

Value

A vectra_node with the joined result.

Examples

f1 <- tempfile(fileext = ".vtr")
f2 <- tempfile(fileext = ".vtr")
write_vtr(data.frame(id = c(1, 2, 3), x = c(10, 20, 30)), f1)
write_vtr(data.frame(id = c(1, 2, 4), y = c(100, 200, 400)), f2)
left_join(tbl(f1), tbl(f2), by = "id") |> collect()
unlink(c(f1, f2))

Define a link between a fact table and a dimension table

Description

Creates a link descriptor that specifies how to join a dimension table to a fact table via one or more key columns.

Usage

link(key, node)

Arguments

Value

A vectra_link object.

Examples

f_obs <- tempfile(fileext = ".vtr")
f_sp  <- tempfile(fileext = ".vtr")
write_vtr(data.frame(sp_id = 1:3, value = c(10, 20, 30)), f_obs)
write_vtr(data.frame(sp_id = 1:3, name = c("A", "B", "C")), f_sp)
lnk <- link("sp_id", tbl(f_sp))
unlink(c(f_obs, f_sp))

Look up columns from linked dimension tables

Description

Resolves columns from dimension tables registered in a vtr_schema(), automatically building the necessary join tree. Reports unmatched keys as a diagnostic message.

Usage

lookup(.schema, ..., .join = "left", .report = TRUE)

Arguments

Details

Column references use dimension$column syntax (e.g., species$name). Columns from the fact table can be referenced by name directly.

When .report = TRUE, each needed dimension is checked for unmatched keys by opening fresh scans of the fact and dimension tables. This adds one extra read pass per dimension but does not affect the lazy result node.

Only dimensions referenced in ... are joined. Unreferenced dimensions are never scanned.

Value

A vectra_node with the selected columns.

Examples

f_obs <- tempfile(fileext = ".vtr")
f_sp  <- tempfile(fileext = ".vtr")
f_ct  <- tempfile(fileext = ".vtr")
write_vtr(data.frame(sp_id = 1:4, ct_code = c("AT", "DE", "FR", "XX"),
                      value = 10:13), f_obs)
write_vtr(data.frame(sp_id = 1:3,
                      name = c("Oak", "Beech", "Pine")), f_sp)
write_vtr(data.frame(ct_code = c("AT", "DE", "FR"),
                      gdp = c(400, 3800, 2700)), f_ct)

s <- vtr_schema(
  fact    = tbl(f_obs),
  species = link("sp_id", tbl(f_sp)),
  country = link("ct_code", tbl(f_ct))
)

# Pull columns from any linked dimension
result <- lookup(s, value, species$name, country$gdp)
collect(result)

unlink(c(f_obs, f_sp, f_ct))

Materialize a vectra node into a reusable in-memory block

Description

Consumes a vectra node (pulling all batches) and stores the result as a persistent columnar block in memory. Unlike nodes, blocks can be probed repeatedly via block_lookup() without re-scanning.

Usage

materialize(.data)

Arguments

Value

A vectra_block object (external pointer to C-level ColumnBlock).

Examples

f <- tempfile(fileext = ".vtr")
df <- data.frame(taxonID = 1:3,
                 canonicalName = c("Quercus robur", "Pinus sylvestris",
                                   "Fagus sylvatica"))
write_vtr(df, f)
blk <- materialize(tbl(f) |> select(taxonID, canonicalName))
hits <- block_lookup(blk, "canonicalName",
                     c("Quercus robur", "Pinus sylvestris"))
unlink(f)

Add or transform columns

Description

Add or transform columns

Usage

mutate(.data, ...)

Arguments

Details

Supported expression types: arithmetic (+, -, *, /, %%), comparison, boolean, is.na(), nchar(), substr(), grepl() (fixed match only). Window functions (row_number(), rank(), dense_rank(), lag(), lead(), cumsum(), cummean(), cummin(), cummax()) are detected automatically and routed to a dedicated window node.

When grouped, window functions respect partition boundaries.

This is a streaming operation for regular expressions; window functions materialize all rows within each partition.

Value

A new vectra_node with mutated columns.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> mutate(kpl = mpg * 0.425144) |> collect() |> head()
unlink(f)

Print a vectra query node

Description

Print a vectra query node

Usage

## S3 method for class 'vectra_node'
print(x, ...)

Arguments

Value

Invisible x.

Extract a single column as a vector

Description

Extract a single column as a vector

Usage

pull(.data, var = -1)

Arguments

Value

A vector.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> pull(mpg) |> head()
unlink(f)

Summarise with variable-length output per group

Description

Like summarise() but allows expressions that return more than one row per group. Currently implemented via collect() fallback.

Usage

reframe(.data, ...)

Arguments

Value

A data.frame (not a lazy node).

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(data.frame(g = c("a", "a", "b"), x = c(1, 2, 3)), f)
tbl(f) |> group_by(g) |> reframe(range_x = range(x))
unlink(f)

Relocate columns

Description

Relocate columns

Usage

relocate(.data, ..., .before = NULL, .after = NULL)

Arguments

Value

A new vectra_node with reordered columns.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> relocate(hp, wt, .before = cyl) |> collect() |> head()
unlink(f)

Rename columns

Description

Rename columns

Usage

rename(.data, ...)

Arguments

Value

A new vectra_node with renamed columns.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> rename(miles_per_gallon = mpg) |> collect() |> head()
unlink(f)

Select columns from a vectra query

Description

Select columns from a vectra query

Usage

select(.data, ...)

Arguments

Value

A new vectra_node with only the selected columns.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> select(mpg, cyl) |> collect() |> head()
unlink(f)

Select rows by position

Description

Select rows by position

Usage

slice(.data, ...)

Arguments

Value

A data.frame with the selected rows.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> slice(1, 3, 5)
unlink(f)

Select first or last rows

Description

Select first or last rows

Usage

slice_head(.data, n = 1L)

slice_tail(.data, n = 1L)

slice_min(.data, order_by, n = 1L, with_ties = TRUE)

slice_max(.data, order_by, n = 1L, with_ties = TRUE)

Arguments

Value

A vectra_node for slice_head() and slice_min/max(..., with_ties = FALSE). A data.frame for slice_tail() and slice_min/max(..., with_ties = TRUE) (the default), since these must materialize all rows.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> slice_head(n = 3) |> collect()
tbl(f) |> slice_min(order_by = mpg, n = 3) |> collect()
tbl(f) |> slice_max(order_by = mpg, n = 3) |> collect()
unlink(f)

Summarise grouped data

Description

Summarise grouped data

Usage

summarise(.data, ..., .groups = NULL)

summarize(.data, ..., .groups = NULL)

Arguments

Details

Aggregation is hash-based by default. When the engine detects it is advantageous, it switches to a sort-based path that can spill to disk, keeping memory bounded regardless of group count.

All aggregation functions accept na.rm = TRUE to skip NA values. Without na.rm, any NA in a group poisons the result (returns NA). R-matching edge cases: sum(na.rm = TRUE) on all-NA returns 0, mean(na.rm = TRUE) on all-NA returns NaN, min/max(na.rm = TRUE) on all-NA returns Inf/-Inf with a warning.

This is a materializing operation.

Value

A vectra_node with one row per group.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> group_by(cyl) |> summarise(avg_mpg = mean(mpg)) |> collect()
unlink(f)

Create a lazy table reference from a .vtr file

Description

Opens a vectra1 file and returns a lazy query node. No data is read until collect() is called.

Usage

tbl(path)

Arguments

Value

A vectra_node object representing a lazy scan of the file.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
node <- tbl(f)
print(node)
unlink(f)

Create a lazy table reference from a CSV file

Description

Opens a CSV file for lazy, streaming query execution. Column types are inferred from the first 1000 rows. No data is read until collect() is called. Gzip-compressed files (.csv.gz) are supported transparently.

Usage

tbl_csv(path, batch_size = .DEFAULT_BATCH_SIZE)

Arguments

Value

A vectra_node object representing a lazy scan of the CSV file.

Examples

f <- tempfile(fileext = ".csv")
write.csv(mtcars, f, row.names = FALSE)
node <- tbl_csv(f)
print(node)
unlink(f)

Create a lazy table reference from a SQLite database

Description

Opens a SQLite database and lazily scans a table. Column types are inferred from declared types in the CREATE TABLE statement. All filtering, grouping, and aggregation is handled by vectra's C engine — no SQL parsing needed. No data is read until collect() is called.

Usage

tbl_sqlite(path, table, batch_size = .DEFAULT_BATCH_SIZE)

Arguments

Value

A vectra_node object representing a lazy scan of the table.

Examples

f <- tempfile(fileext = ".sqlite")
write_sqlite(mtcars, f, "cars")
node <- tbl_sqlite(f, "cars")
node |> filter(cyl == 6) |> collect()
unlink(f)

Create a lazy table reference from a GeoTIFF raster

Description

Opens a GeoTIFF file and returns a lazy query node. Each pixel becomes a row with columns x, y, band1, band2, etc. Coordinates are pixel centers derived from the affine geotransform. NoData values become NA.

Usage

tbl_tiff(path, batch_size = .TIFF_BATCH_SIZE)

Arguments

Details

Use filter(x >= ..., y <= ...) for extent-based cropping and filter(band1 > ...) for value-based cropping. Results can be converted back to a raster with terra::rast(df, type = "xyz").

Value

A vectra_node object representing a lazy scan of the raster.

Examples

f <- tempfile(fileext = ".tif")
df <- data.frame(x = as.double(rep(1:4, 3)),
                 y = as.double(rep(1:3, each = 4)),
                 band1 = as.double(1:12))
write_tiff(df, f)
node <- tbl_tiff(f)
node |> filter(band1 > 6) |> collect()
unlink(f)

Create a lazy table reference from an Excel (.xlsx) file

Description

Reads a sheet from an Excel workbook into a vectra node for lazy query execution. The sheet is read into memory via openxlsx2::read_xlsx() and then converted to vectra's internal format. Requires the openxlsx2 package.

Usage

tbl_xlsx(path, sheet = 1L, batch_size = .DEFAULT_BATCH_SIZE)

Arguments

Value

A vectra_node object representing a lazy scan of the sheet.

Examples

if (requireNamespace("openxlsx2", quietly = TRUE)) {
  f <- tempfile(fileext = ".xlsx")
  openxlsx2::write_xlsx(mtcars, f)
  node <- tbl_xlsx(f)
  node |> filter(cyl == 6) |> collect()
  unlink(f)
}

Extract raster values at point coordinates

Description

Samples band values from a GeoTIFF at specific (x, y) locations using the file's affine geotransform. Only the strips containing query points are read, making this efficient for sparse point sets on large rasters.

Usage

tiff_extract_points(path, x, y = NULL)

Arguments

Details

Points that fall outside the raster extent return NA for all bands. Pixel assignment uses nearest-pixel rounding (i.e., the point is assigned to the pixel whose center is closest).

Value

A data.frame with columns x, y, band1, band2, etc. One row per input point, in the same order as the input.

Examples

f <- tempfile(fileext = ".tif")
df <- data.frame(x = as.double(rep(1:4, 3)),
                 y = as.double(rep(1:3, each = 4)),
                 band1 = as.double(1:12))
write_tiff(df, f)

# Sample at specific locations via data.frame
pts <- data.frame(x = c(2, 3), y = c(1, 2))
tiff_extract_points(f, pts)

# Or pass x and y separately
tiff_extract_points(f, x = c(2, 3), y = c(1, 2))
unlink(f)

Read GDAL_METADATA from a GeoTIFF

Description

Returns the GDAL_METADATA XML string (TIFF tag 42112) embedded in a GeoTIFF file. Returns NA if the tag is not present.

Usage

tiff_metadata(path)

Arguments

Value

A single character string containing the XML, or NA_character_.

Examples

f <- tempfile(fileext = ".tif")
df <- data.frame(x = 1:4, y = rep(1:2, each = 2), band1 = as.double(1:4))
write_tiff(df, f, metadata = "<GDALMetadata></GDALMetadata>")
tiff_metadata(f)
unlink(f)

Keep only columns from mutate expressions

Description

Like mutate() but drops all other columns.

Usage

transmute(.data, ...)

Arguments

Value

A new vectra_node with only the computed columns.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> transmute(kpl = mpg * 0.425) |> collect() |> head()
unlink(f)

Remove grouping from a vectra query

Description

Remove grouping from a vectra query

Usage

ungroup(x, ...)

Arguments

Value

An ungrouped vectra_node.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)
tbl(f) |> group_by(cyl) |> ungroup()
unlink(f)

Create a star schema over linked vectra tables

Description

Registers a fact table with named dimension links. The schema enables lookup() to resolve columns from dimension tables without writing explicit joins.

Usage

vtr_schema(fact, ...)

Arguments

Value

A vectra_schema object.

Examples

f_obs <- tempfile(fileext = ".vtr")
f_sp  <- tempfile(fileext = ".vtr")
f_ct  <- tempfile(fileext = ".vtr")
write_vtr(data.frame(sp_id = 1:3, ct_code = c("AT", "DE", "FR"),
                      value = 10:12), f_obs)
write_vtr(data.frame(sp_id = 1:3,
                      name = c("Oak", "Beech", "Pine")), f_sp)
write_vtr(data.frame(ct_code = c("AT", "DE", "FR"),
                      gdp = c(400, 3800, 2700)), f_ct)

s <- vtr_schema(
  fact    = tbl(f_obs),
  species = link("sp_id", tbl(f_sp)),
  country = link("ct_code", tbl(f_ct))
)
print(s)
unlink(c(f_obs, f_sp, f_ct))

Write query results or a data.frame to a CSV file

Description

For vectra_node inputs, data is streamed batch-by-batch to disk without materializing the full result in memory. For data.frame inputs, the data is written directly.

Usage

write_csv(x, path, ...)

Arguments

Value

Invisible NULL.

Examples

f <- tempfile(fileext = ".vtr")
write_vtr(mtcars[1:5, ], f)
csv <- tempfile(fileext = ".csv")
tbl(f) |> write_csv(csv)
unlink(c(f, csv))

Write query results or a data.frame to a SQLite table

Description

For vectra_node inputs, data is streamed batch-by-batch to disk without materializing the full result in memory. For data.frame inputs, the data is written directly.

Usage

write_sqlite(x, path, table, ...)

Arguments

Value

Invisible NULL.

Examples

db <- tempfile(fileext = ".sqlite")
f <- tempfile(fileext = ".vtr")
write_vtr(mtcars[1:5, ], f)
tbl(f) |> write_sqlite(db, "cars")
unlink(c(f, db))

Write query results to a GeoTIFF file

Description

The data must contain x and y columns (pixel center coordinates) and one or more numeric band columns. Grid dimensions and geotransform are inferred from the x/y coordinate arrays. Missing pixels are written as NaN (or the type-appropriate nodata value for integer pixel types).

Usage

write_tiff(
  x,
  path,
  compress = FALSE,
  pixel_type = "float64",
  metadata = NULL,
  ...
)

Arguments

Value

Invisible NULL.

Examples

# Write as int16 with DEFLATE compression
df <- data.frame(x = 1:4, y = rep(1:2, each = 2), band1 = c(100, 200, 300, 400))
f <- tempfile(fileext = ".tif")
write_tiff(df, f, compress = TRUE, pixel_type = "int16")
unlink(f)

Write data to a .vtr file

Description

For vectra_node inputs (lazy queries from any format: CSV, SQLite, TIFF, or another .vtr), data is streamed batch-by-batch to disk without materializing the full result in memory. Each batch becomes one row group. The output file is written atomically (via temp file + rename) so readers never see a partial file.

Usage

write_vtr(
  x,
  path,
  compress = c("fast", "small", "none"),
  batch_size = NULL,
  col_types = NULL,
  quantize = NULL,
  spatial = NULL,
  ...
)

Arguments

Details

For data.frame inputs, the data is written directly from memory.

Value

Invisible NULL.

Examples

# From a data.frame
f <- tempfile(fileext = ".vtr")
write_vtr(mtcars, f)

# Streaming format conversion (CSV -> VTR)
csv <- tempfile(fileext = ".csv")
write.csv(mtcars, csv, row.names = FALSE)
f2 <- tempfile(fileext = ".vtr")
tbl_csv(csv) |> write_vtr(f2)

unlink(c(f, f2, csv))