extract_tables: extract_tables
In ropensci/tabulizer: Extract Tables from PDF Documents

View source: R/extract_tables.R

extract_tables

R Documentation

extract_tables

Description

Extract tables from a file

Usage

extract_tables(
  file,
  pages = NULL,
  area = NULL,
  columns = NULL,
  col_names = TRUE,
  guess = TRUE,
  method = c("decide", "lattice", "stream"),
  output = c("tibble", "matrix", "character", "asis", "csv", "tsv", "json"),
  outdir = NULL,
  password = NULL,
  encoding = NULL,
  copy = FALSE,
  ...
)

Arguments

`file`	A character string specifying the path or URL to a PDF file.
`pages`	An optional integer vector specifying pages to extract from.
`area`	An optional list, of length equal to the number of pages specified, where each entry contains a four-element numeric vector of coordinates (top,left,bottom,right) containing the table for the corresponding page. As a convenience, a list of length 1 can be used to extract the same area from all (specified) pages. Only specify `area` or `columns`. Warning: `area` is ignored if `guess` is `TRUE`.
`columns`	An optional list, of length equal to the number of pages specified, where each entry contains a numeric vector of horizontal (x) coordinates separating columns of data for the corresponding page. As a convenience, a list of length 1 can be used to specify the same columns for all (specified) pages. Only specify `area` or `columns`. Warning: `columns` is ignored if `guess` is `TRUE`.
`col_names`	A logical indicating whether to include column names in the output tibbles. Default is `TRUE`.
`guess`	A logical indicating whether to guess the locations of tables on each page. If `FALSE`, `area` or `columns` must be specified; if `TRUE`, `area` and `columns` are ignored.
`method`	A string identifying the preferred method of table extraction. `method = "decide"` (default) automatically decide (for each page) whether spreadsheet-like formatting is present and "lattice" is appropriate `method = "lattice"` use Tabula's spreadsheet extraction algorithm `method = "stream"` use Tabula's basic extraction algorithm
`output`	A function to coerce the Java response object (a Java ArrayList of Tabula Tables) to some output format. The default method, “matrices”, returns a list of character matrices. See Details for other options.
`outdir`	Output directory for files if `output` is set to `"csv"`, `"tsv"` or `"json"`, ignored otherwise. If equals `NULL` (default), uses R sessions temporary directory `tempdir()`.
`password`	Optionally, a character string containing a user password to access a secured PDF.
`encoding`	Optionally, a character string specifying an encoding for the text, to be passed to the assignment method of `Encoding`.
`copy`	Specifies whether the original local file(s) should be copied to `tempdir()` before processing. `FALSE` by default. The argument is ignored if `file` is URL.
`...`	These are additional arguments passed to the internal functions dispatched by `method`.

Details

This function mimics the behavior of the Tabula command line utility. It returns a list of R character matrices containing tables extracted from a file by default. This response behavior can be changed by using the following options.

output = "tibble" attempts to coerce the structure returned by method = "character" into a list of tibbles and returns character strings where this fails.
output = "character" returns a list of single-element character vectors, where each vector is a tab-delimited, line-separate string of concatenated table cells.
output = "csv" writes the tables to comma-separated (CSV) files using Tabula's CSVWriter method in the same directory as the original PDF. method = "tsv" does the same but with tab-separated (TSV) files using Tabula's TSVWriter and method = "json" does the same using Tabula's JSONWriter method. Any of these three methods return the path to the directory containing the extract table files.
output = "asis" returns the Java object reference, which can be useful for debugging or for writing a custom parser.

extract_areas implements this functionality in an interactive mode allowing the user to specify extraction areas for each page.

Value

By default, a list of character matrices. This can be changed by specifying an alternative value of method (see Details).

Author(s)

Thomas J. Leeper <thosjleeper@gmail.com>, Tom Paskhalis <tpaskhalis@gmail.com>

References

Tabula

Examples

# simple demo file
f <- system.file("examples", "mtcars.pdf", package = "tabulapdf")

# extract tables from only second page
extract_tables(f, pages = 2)

ropensci/tabulizer documentation built on Sept. 25, 2024, 11:58 p.m.