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Flip geometries horizontally or vertically

Source: R/ddbs_affine.R
ddbs_flip.Rd

Reflects geometries across their centroid. By default, flipping is applied relative to the centroid of all geometries; if by_feature = TRUE, each geometry is flipped relative to its own centroid.

Usage

ddbs_flip(
  x,
  direction = c("horizontal", "vertical"),
  by_feature = FALSE,
  conn = NULL,
  name = NULL,
  mode = NULL,
  overwrite = FALSE,
  quiet = FALSE
)

Arguments

x

Input spatial data. Can be:

  • A duckspatial_df object (lazy spatial data frame via dbplyr)

  • An sf object

  • A tbl_lazy from dbplyr

  • A character string naming a table/view in conn

Data is returned from this object.

direction

character string specifying the flip direction: "horizontal" (default) or "vertical". Horizontal flips across the Y-axis (left-right), vertical flips across the X-axis (top-bottom)

by_feature

Logical. If TRUE, the geometric operation is applied separately to each geometry. If FALSE, the geometric operation is applied to the data as a whole.

conn

A connection object to a DuckDB database. If NULL, the function runs on a temporary DuckDB database.

name

A character string of length one specifying the name of the table, or a character string of length two specifying the schema and table names. If NULL (the default), no table is written and the result is returned as a duckspatial_df or sf object, depending on mode

mode

Character. Controls the return type. Options:

  • "duckspatial" (default): Lazy spatial data frame backed by dbplyr/DuckDB

  • "sf": Eagerly collected sf object (uses memory)

Can be set globally via ddbs_options(mode = "...") or per-function via this argument. Per-function overrides global setting.

overwrite

Boolean. whether to overwrite the existing table if it exists. Defaults to FALSE. This argument is ignored when name is NULL.

quiet

A logical value. If TRUE, suppresses any informational messages. Defaults to FALSE.

Value

Depends on the mode argument (or global preference set by ddbs_options):

  • duckspatial (default): A duckspatial_df (lazy spatial data frame) backed by dbplyr/DuckDB.

  • sf: An eagerly collected object in R memory, that will return the same data type as the sf equivalent (e.g. sf or units vector).

When name is provided, the result is also written as a table or view in DuckDB and the function returns TRUE (invisibly).

Examples

if (FALSE) { # \dontrun{
## load packages
library(duckspatial)

# create a duckdb database in memory (with spatial extension)
conn <- ddbs_create_conn(dbdir = "memory")

## read data
argentina_ddbs <- ddbs_open_dataset(
  system.file("spatial/argentina.geojson", 
  package = "duckspatial")
)

## store in duckdb
ddbs_write_table(conn, argentina_ddbs, "argentina")

## flip all features together as a whole (default)
ddbs_flip(conn = conn, "argentina", direction = "horizontal", by_feature = FALSE)

## flip each feature independently
ddbs_flip(conn = conn, "argentina", direction = "horizontal", by_feature = TRUE)

## flip without using a connection
ddbs_flip(argentina_ddbs, direction = "horizontal")
} # }