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PLAYA-PDF is a LAzY Analyzer for PDF 🏖️

About

There are already too many PDF libraries, unfortunately none of which does everything that everybody wants it to do, and we probably don't need another one. It is not recommended that you use this library for anything at all, but if you were going to use it for something, it would be specifically one of these things and nothing else:

  1. Accessing the document catalog, page tree, structure tree, content streams, cross-reference table, XObjects, and other low-level PDF metadata.
  2. Obtaining the absolute position and attributes of every character, line, path, and image in every page of a PDF.

If you just want to extract text from a PDF, there are a lot of better and faster tools and libraries out there, see these benchmarks for a summary (TL;DR pypdfium2 is probably what you want, but pdfplumber does a nice job of converting PDF to ASCII art).

The purpose of PLAYA is to provide an efficent, pure-Python and Pythonic (for its author's definition of the term), lazy interface to the internals of PDF files.

Installation

Installing it should be really simple as long as you have Python 3.8 or newer:

pipx install playa-pdf

Yes it's not just "playa". Sorry about that.

Usage

Do you want to get stuff out of a PDF? You have come to the right place! Let's open up a PDF and see what's in it:

pdf = playa.open("my_awesome_document.pdf")
raw_byte_stream = pdf.buffer
a_bunch_of_tokens = list(pdf.tokens)
a_bunch_of_indirect_objects = list(pdf)

The raw PDF tokens and objects are probably not terribly useful to you, but you might find them interesting. Note that these are "indirect objects" where the actual object is accompanied by an object number and generation number:

for objid, genno, obj in pdf:
    ...
# or also
for obj in pdf:
    obj.objid, obj.genno, obj.obj

Also, these will only be the top-level objects and not those found inside object streams (the streams are themselves indirect objects). You can access all objects directly by indexing the PDF document:

a_particular_object = pdf[42]

It probably has some pages. How many? What are their numbers/labels? (they could be things like "xviii", 'a", or "42", for instance)

npages = len(pdf.pages)
page_numbers = [page.label for page in pdf.pages]

What's in the table of contents?

for entry in pdf.outlines:
    ...

If you are lucky it has a "logical structure tree". The elements here might even be referenced from the table of contents! (or, they might not... with PDF you never know)

structure = pdf.structtree
for element in structure:
   for child in element:
       ...

Now perhaps we want to look at a specific page. Okay! You can also look at its contents, more on that in a bit:

page = pdf.pages[0]        # they are numbered from 0
page = pdf.pages["xviii"]  # but you can get them by label (a string)
page = pdf.pages["42"]  # or "logical" page number (also a string)
print(f"Page {page.label} is {page.width} x {page.height}")

Accessing content

What are these "contents" of which you speak, which were surely created by a Content Creator? Well, you can look at the stream of tokens or mysterious PDF objects:

for token in page.tokens:
    ...
for object in page.contents:
    ...

But that isn't very useful, so you can also access actual textual and graphical objects (if you wanted to, for instance, do layout analysis).

for item in page:
    ...

Because it is quite inefficient to expand, calculate, and copy every possible piece of information, PLAYA gives you some options here. Wherever possible this information can be computed lazily, but this involves some more work on the user's part.

Dictionary-based API

If, on the other hand, you are lazy, then you can just use page.layout, which will flatten everything for you into a friendly dictionary representation (but it is a TypedDict) which, um, looks a lot like what pdfplumber gives you, except in the coordinate space defined previously.

for dic in page.layout:
    print("it is a {dic['object_type']} at ({dic['x0']}", {dic['y0']}))
    print("    the color is {dic['stroking_color']}")
    print("    the text is {dic['text']}")
    print("    it is in MCS {dic['mcid']} which is a {dic['tag']}")
    print("    it is also in Form XObject {dic['xobjid']}")

This is for instance quite useful for doing "Artificial Intelligence", or if you like wasting time and energy for no good reason, but I repeat myself. For instance, you can write page.layout to a CSV file:

writer = DictWriter(outfh, fieldnames=playa.fieldnames)
writer.writeheader()
for dic in pdf.layout:
    writer.writerow(dic)

you can also create a Pandas DataFrame:

df = pandas.DataFrame.from_records(pdf.layout)

or a Polars DataFrame or LazyFrame:

df = polars.DataFrame(pdf.layout, schema=playa.schema)

If you have more specific needs or want better performance, then read on.

An important note about coordinate spaces

Wait, what is this "absolute position" of which you speak, and which PLAYA gives you? It's important to understand that there is no definition of "device space" in the PDF standard, and I quote (PDF 1.7 sec 8.3.2.2):

A particular device’s coordinate system is called its device space. The origin of the device space on different devices can fall in different places on the output page; on displays, the origin can vary depending on the window system. Because the paper or other output medium moves through different printers and imagesetters in different directions, the axes of their device spaces may be oriented differently.

You may immediately think of CSS when you hear the phrase "absolute position" and this is exactly what PLAYA gives you as its default device space, specifically:

  • Units are default user space units (1/72 of an inch).
  • (0, 0) is the top-left corner of the page, as defined by its MediaBox after rotation is applied.
  • Coordinates increase from the top-left corner of the page towards the bottom-left corner.

However, for compatibility with pdfminer.six, you can also pass space="page" to playa.open. In this case, (0, 0) is the bottom-left corner of the page as defined by the MediaBox, after rotation, and coordinates increase from the bottom-left corner of the page towards the top-right, as they do in PDF user space.

If you don't care about absolute positioning, you can use space="user", which may be somewhat faster in the future (currently it isn't). In this case, no translation or rotation of the default user space is done (in other words any values of MediaBox or Rotate in the page dictionary are simply ignored).

Lazy object API

Fundamentally you may just want to know what is where on the page, and PLAYA has you covered there (note that the bbox is normalized, and in the aforementioned interpretation of "device space"):

for obj in page:
    print(f"{obj.object_type} at {obj.bbox}")
    left, top, right, bottom = obj.bbox
    print(f"  top left is {left, top}")
    print(f"  bottom right is {right, botom}")

Another important piece of information (which pdfminer.six does not really handle) is the relationship between layout and logical structure, done using marked content sections:

for obj in page:
    print(f"{obj.object_type} is in marked content section {obj.mcs.mcid}")
    print(f"    which is tag {obj.mcs.tag.name}")
    print(f"    with properties {obj.mcs.tag.props}")

The mcid here is the same one referenced in elements of the structure tree as shown above (but remember that tag has nothing to do with the structure tree element, because Reasons). A marked content section does not necessarily have a mcid or props, but it will always have a tag.

PDF also has the concept of "marked content points". PLAYA suports these with objects of object_type == "tag". The tag name and properties are also accessible via the mcs attribute.

Form XObjects

A PDF page may also contain "Form XObjects" which are like tiny embedded PDF documents (they have nothing to do with fillable forms). The lazy API (because it is lazy) will not expand these for you which may be a source of surprise. You can identify them because they have object_type == "xobject". The layout objects inside them are accessible by iteration, as with pages (but not documents):

for obj in page:
    if obj.object_type == "xobject":
        for item in obj:
            ...

You can also iterate over them in the page context with page.xobjects:

for xobj in page.xobjects:
    for item in xobj:
        ...

Exceptionally, these have a few more features than the ordinary ContentObject - you can look at their raw stream contents as well as the tokens, and you can also see raw, mysterious PDF objects with contents.

Graphics state

You may also wish to know what color an object is, and other aspects of what PDF refers to as the graphics state, which is accessible through obj.gstate. This is a mutable object, and since there are quite a few parameters in the graphics state, PLAYA does not create a copy of it for every object in the layout - you are responsible for saving them yourself if you should so desire. This is not particularly onerous, because the parameters themselves are immutable:

for obj in page:
    print(f"{obj.object_type} at {obj.bbox} is:")
    print(f"    {obj.gstate.scolor} stroking color")
    print(f"    {obj.gstate.ncolor} non-stroking color")
    print(f"    {obj.gstate.dash} dashing style")
    my_stuff = (obj.dash, obj.gstate.scolor, obj.gstate.ncolor)
    other_stuff.append(my_stuff)  # it's safe there

For compatbility with pdfminer.six, PLAYA, even though it is not a layout analyzer, can do some basic interpretation of paths. Again, this is lazy. If you don't care about them, you just get objects with object_type of "path", which you can ignore. PLAYA won't even compute the bounding box (which isn't all that slow, but still). If you do care, then you have some options. You can look at the actual path segments in user space (fast):

for seg in path.raw_segments:
   print(f"segment: {seg}")

Or in PLAYA's "device space" (not so fast):

for seg in path.segments:
   print(f"segment: {seg}")

This API doesn't try to interpret paths for you. You only get PathSegments. But for convenience you can get them grouped by subpaths as created using the m or re operators:

for subpath in path:
   for seg in subpath.segments:
       print(f"segment: {seg}")

Text Objects

Since most PDFs consist primarily of text, obviously you may wish to know something about the actual text (or the ActualText, which you can sometimes find in obj.mcs.tag.props["ActualText"]). This is more difficult than it looks, as fundamentally PDF just positions arbitrarily numbered glyphs on a page, and the vast majority of PDFs embed their own fonts, using subsetting to include only the glyphs actually used.

Whereas pdfminer.six would break down text objects into their individual glyphs (which might or might not correspond to characters), this is not always what you want, and moreover it is computationally quite expensive. So PLAYA, by default, does not do this. If you don't need to know the actual bounding box of a text object, then don't access obj.bbox and it won't be computed. If you don't need to know the position of each glyph but simply want the Unicode characters, then just look at obj.chars.

Also, a lot of PDFs, especially ones produced by OCR, don't organize text objects in any meaningful fashion, so you will want to actually look at the glyphs. This becomes a matter of iterating over the item, giving you, well, more items, which are the individual glyphs:

for glyph in item:
    print("Glyph has CID {glyph.cid} and Unicode {glyph.text}")

By default PLAYA, following the PDF specification, considers the grouping of glyphs into strings irrelevant by default. I might consider separating the strings in the future.

PDF has the concept of a text state which determines some aspects of how text is rendered. You can obviously access this though glyph.textstate - note that the text state, like the graphics state, is mutable, so you will have to copy it or save individual parameters that you might care about.

PLAYA doesn't guarantee that text objects come at you in anything other than the order they occur in the file (but it does guarantee that).

In some cases might want to look at the abovementioned ActualText attribute to reliably extract text, particularly if the PDF was created by certain versions of LibreOffice, but in their infinite wisdom, Adobe made ActualText a property of marked content sections and not text objects, so you may be out of luck if you want to actually match these characters to glyphs. Sorry, I don't write the standards.

Conclusion

As mentioned earlier, if you really just want to do text extraction, there's always pdfplumber, pymupdf, pypdfium2, pikepdf, pypdf, borb, etc, etc, etc.

Acknowledgement

This repository obviously includes code from pdfminer.six. Original license text is included in LICENSE. The license itself has not changed!