Package 'tabulapdf' reference manual

Title:	Extract Tables from PDF Documents
Description:	Bindings for the 'Tabula' <https://tabula.technology/> 'Java' library, which can extract tables from PDF files. This tool can reduce time and effort in data extraction processes in fields like investigative journalism. It allows for automatic and manual table extraction, the latter facilitated through a 'Shiny' interface, enabling manual areas selection\ with a computer mouse for data retrieval.
Authors:	Thomas J. Leeper [aut] , Mauricio Vargas Sepulveda [aut, cre] , Tom Paskhalis [aut] , Manuel Aristaran [ctb], David Gohel [ctb] (rOpenSci reviewer), Lincoln Mullen [ctb] (rOpenSci reviewer), Munk School of Global Affairs and Public Policy [fnd]
Maintainer:	Mauricio Vargas Sepulveda <[email protected]>
License:	Apache License (>= 2)
Version:	1.0.5-5
Built:	2024-11-25 16:44:15 UTC
Source:	CRAN

tabulapdf

Description

Bindings for “Tabula” PDF Table Extractor Library

Details

Tabula is a Java library designed to computationally extract tables from PDF documents. tabulapdf provides a thin R package with bindings to the library. It presently offers two principal functions: extract_tables, which mimics the command line functionality of Tabula, and extract_areas which provides an interactive interface to the former.

Author(s)

Thomas J. Leeper <[email protected]>

References

tabula

extract_metadata

Description

Extract metadata from a file

Usage

extract_metadata(file, password = NULL, copy = FALSE)
extract_metadata(file, password = NULL, copy = FALSE)

Arguments

`file`	A character string specifying the path or URL to a PDF file.
`password`	Optionally, a character string containing a user password to access a secured PDF.
`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.

Details

This function extracts metadata from a PDF

Value

A list.

Author(s)

Thomas J. Leeper <[email protected]>

Examples

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

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

extract_metadata(f)

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,
  ...
)
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 <[email protected]>, Tom Paskhalis <[email protected]>

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

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

extract_text

Description

Extract text from a file

Usage

extract_text(
  file,
  pages = NULL,
  area = NULL,
  password = NULL,
  encoding = NULL,
  copy = FALSE
)
extract_text(
  file,
  pages = NULL,
  area = 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.
`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.

Details

This function converts the contents of a PDF file into a single unstructured character string.

Value

If pages = NULL (the default), a length 1 character vector, otherwise a vector of length length(pages).

Author(s)

Thomas J. Leeper <[email protected]>

Examples

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

# extract all text
extract_text(f)

# extract all text from page 1 only
extract_text(f, pages = 1)

# extract text from selected area only
extract_text(f, area = list(c(209.4, 140.5, 304.2, 500.8)))
# simple demo file
f <- system.file("examples", "fortytwo.pdf", package = "tabulapdf")

# extract all text
extract_text(f)

# extract all text from page 1 only
extract_text(f, pages = 1)

# extract text from selected area only
extract_text(f, area = list(c(209.4, 140.5, 304.2, 500.8)))

Page length and dimensions

Description

Get Page Length and Dimensions

Usage

get_page_dims(file, doc, pages = NULL, password = NULL, copy = FALSE)

get_n_pages(file, doc, password = NULL, copy = FALSE)
get_page_dims(file, doc, pages = NULL, password = NULL, copy = FALSE)

get_n_pages(file, doc, password = NULL, copy = FALSE)

Arguments

`file`	A character string specifying the path or URL to a PDF file.
`doc`	Optionally,, in lieu of `file`, an rJava reference to a PDDocument Java object.
`pages`	An optional integer vector specifying pages to extract from.
`password`	Optionally, a character string containing a user password to access a secured PDF.
`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.

Details

get_n_pages returns the page length of a PDF document. get_page_dims extracts the dimensions of specified pages in a PDF document. This can be useful for figuring out how to specify the area argument in extract_tables

Value

For get_n_pages, an integer. For get_page_dims, a list of two-element numeric vectors specifying the width and height of each page, respectively.

Author(s)

Thomas J. Leeper <[email protected]>

References

Tabula

Examples

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

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

get_n_pages(file = f)
get_page_dims(f)

extract_areas

Description

Interactively identify areas and extract

Usage

locate_areas(
  file,
  pages = NULL,
  thumbnails = NULL,
  resolution = 60L,
  widget = c("shiny", "native", "reduced"),
  copy = FALSE
)

extract_areas(file, pages = NULL, guess = FALSE, copy = FALSE, ...)
locate_areas(
  file,
  pages = NULL,
  thumbnails = NULL,
  resolution = 60L,
  widget = c("shiny", "native", "reduced"),
  copy = FALSE
)

extract_areas(file, pages = NULL, guess = FALSE, copy = FALSE, ...)

Arguments

`file`	A character string specifying the path to a PDF file. This can also be a URL, in which case the file will be downloaded to the R temporary directory using `download.file`.
`pages`	An optional integer vector specifying pages to extract from. To extract multiple tables from a given page, repeat the page number (e.g., `c(1,2,2,3)`).
`thumbnails`	A directory containing prefetched thumbnails created with the function `make_thumbnails`. This will greatly increase loading speed.
`resolution`	An integer specifying the resolution of the PNG images conversions. A low resolution is used by default to speed image loading.
`widget`	A one-element character vector specifying the type of “widget” to use for locating the areas. The default (“shiny”) is a shiny widget. The alternatives are a widget based on the native R graphics device (“native”, where available), or a very reduced functionality model (“reduced”).
`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.
`guess`	See `extract_tables` (note the different default value).
`...`	Other arguments passed to `extract_tables`.

Details

extract_areas is an interactive mode for extract_tables allowing the user to specify areas of each PDF page in a file that they would like extracted. When used, each page is rendered to a PNG file and displayed in an R graphics window sequentially, pausing on each page to call locator so the user can click and highlight an area to extract.

The exact behaviour is a somewhat platform-dependent, and depends on the value of widget (and further, whether you are working in RStudio or the R console). In RStudio (where widget = "shiny"), a Shiny gadget is provided which allows the user to click and drag to select areas on each page of a file, clicking “Done” on each page to advance through them. It is not possible to return to previous pages. In the R console, a Shiny app will be launched in a web browser.

For other values of widget, functionality is provided through the graphics device. If graphics events are supported, then it is possibly to interactively highlight a page region, make changes to that region, and navigate through the pages of the document while retaining the area highlighted on each page. If graphics events are not supported, then some of this functionality is not available (see below).

In full functionality mode (widget = "native"), areas are input in a native graphics device. For each page, the first mouse click on a page initializes a highlighting rectangle; the second click confirms it. If unsatisfied with the selection, the process can be repeated. The window also responds to keystrokes. PgDn, Right, and Down advance to the next page image, while PgUp, Left, and Up return to the previous page image. Home returns to the first page image and End advances to the final page image. Q quits the interactive mode and proceeds with extraction. When navigating between pages, any selected areas will be displayed and can be edited. Delete removes a highlighted area from a page (and then displays it again). (This mode may not work correctly from within RStudio.)

In reduced functionality mode (where widget = "reduced" or on platforms where graphics events are unavailable), the interface requires users to indicate the upper-left and lower-right (or upper-right and lower-left) corners of an area on each page, this area will be briefly confirmed with a highlighted rectangle and the next page will be displayed. Dynamic page navigation and area editing are not possible.

In any of these modes, after the areas are selected, extract_areas passes these user-defined areas to extract_tables. locate_areas implements the interactive component only, without actually extracting; this might be useful for interactive work that needs some modification before executing extract_tables computationally.

Value

For extract_areas, see extract_tables. For locate_areas, a list of four-element numeric vectors (top,left,bottom,right), one per page of the file.

Author(s)

Thomas J. Leeper <[email protected]>

Examples

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

  # locate areas only, using Shiny app
  locate_areas(f)

  # locate areas only, using native graphics device
  locate_areas(f, widget = "shiny")

  # locate areas and extract
  extract_areas(f)
}
if (interactive()) {
  # simple demo file
  f <- system.file("examples", "mtcars.pdf", package = "tabulapdf")

  # locate areas only, using Shiny app
  locate_areas(f)

  # locate areas only, using native graphics device
  locate_areas(f, widget = "shiny")

  # locate areas and extract
  extract_areas(f)
}

make_thumbnails

Description

Convert Pages to Image Thumbnails

Usage

make_thumbnails(
  file,
  outdir = NULL,
  pages = NULL,
  format = c("png", "jpeg", "bmp", "gif"),
  resolution = 72,
  password = NULL,
  copy = FALSE
)
make_thumbnails(
  file,
  outdir = NULL,
  pages = NULL,
  format = c("png", "jpeg", "bmp", "gif"),
  resolution = 72,
  password = NULL,
  copy = FALSE
)

Arguments

`file`	A character string specifying the path or URL to a PDF file.
`outdir`	An optional character string specifying a directory into which to split the resulting files. If `NULL`, the `outdir` is `tempdir()`. If `file` is a URL, both file and thumbnails are stored in the R session's temporary directory.
`pages`	An optional integer vector specifying pages to extract from.
`format`	A character string specifying an image file format.
`resolution`	A numeric value specifying the image resolution in DPI.
`password`	Optionally, a character string containing a user password to access a secured PDF.
`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.

Details

This function save each (specified) page of a document as an image with 720 dpi resolution. Images are saved in the same directory as the original file, with file names specified by the original file name, a page number, and the corresponding file format extension.

Value

A character vector of file paths.

Note

This may generate Java “INFO” messages in the console, which can be safely ignored.

Author(s)

Thomas J. Leeper <[email protected]>

References

Tabula

Examples

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

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

make_thumbnails(f)

Split and merge PDFs

Description

Split PDF into separate pages or merge multiple PDFs into one.

Usage

split_pdf(file, outdir = NULL, password = NULL, copy = FALSE)

merge_pdfs(file, outfile, copy = FALSE)
split_pdf(file, outdir = NULL, password = NULL, copy = FALSE)

merge_pdfs(file, outfile, copy = FALSE)

Arguments

`file`	For `merge_pdfs`, a character vector specifying the path to one or more local PDF files. For `split_pdf`, a character string specifying the path or URL to a PDF file.
`outdir`	For `split_pdf`, an optional character string specifying a directory into which to split the resulting files. If `NULL`, the `outdir` is `tempdir()`. If `file` is a URL, both the original file and separate pages are stored in the R session's temporary directory.
`password`	Optionally, a character string containing a user password to access a secured PDF. Currently, encrypted PDFs cannot be merged with `merge_pdfs`.
`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.
`outfile`	For `merge_pdfs`, a character string specifying the path to the PDF file to create from the merged documents.

Details

split_pdf splits the file listed in file into separate one-page doucments. merge_pdfs creates a single PDF document from multiple separate PDF files.

Value

For split_pdfs, a character vector specifying the output file names, which are patterned after the value of file. For merge_pdfs, the value of outfile.

Author(s)

Thomas J. Leeper <[email protected]>

Examples

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

# split PDF by page
sf <- split_pdf(f)

# merge pdf
mf <- file.path(tempdir(), "merged.pdf")
merge_pdfs(sf, mf)
get_n_pages(mf)
# simple demo file
f <- system.file("examples", "mtcars.pdf", package = "tabulapdf")
get_n_pages(file = f)

# split PDF by page
sf <- split_pdf(f)

# merge pdf
mf <- file.path(tempdir(), "merged.pdf")
merge_pdfs(sf, mf)
get_n_pages(mf)

rJava logging

Description

Toggle verbose rJava logging

Usage

stop_logging()
stop_logging()

Details

This function turns off the somewhat verbose rJava logging, most of which is uninformative. It is called automatically when tabulapdf is attached via library(), require, etc. To keep logging on, load the package namespace using requireNamespace("tabulapdf") and reference functions in using fully qualified references (e.g., tabulapdf::extract_tables().

Value

NULL, invisibly.

Note

This resets a global Java setting and may affect logging of other rJava operations, requiring a restart of R.

Author(s)

Thomas J. Leeper <[email protected]>

Examples

stop_logging()
stop_logging()

Package 'tabulapdf'

Help Index

tabulapdf

Description

Details

Author(s)

References

See Also

extract_metadata

Description

Usage

Arguments

Details

Value

Author(s)

See Also

Examples

extract_tables

Description

Usage

Arguments

Details

Value

Author(s)

References

See Also

Examples

extract_text

Description

Usage

Arguments

Details

Value

Author(s)

See Also

Examples

Page length and dimensions

Description

Usage

Arguments

Details

Value

Author(s)

References

See Also

Examples

extract_areas

Description

Usage

Arguments

Details

Value

Author(s)

See Also

Examples

make_thumbnails

Description

Usage

Arguments

Details

Value

Note

Author(s)

References

See Also

Examples

Split and merge PDFs

Description

Usage

Arguments

Details

Value

Author(s)

See Also

Examples

rJava logging

Description

Usage

Details

Value