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662c091 Oct 22, 2017
@dpapathanasiou @maciejbiesek @faaez
205 lines (171 sloc) 7.26 KB
import sys
import os
from binascii import b2a_hex
### pdf-miner requirements
from pdfminer.pdfparser import PDFParser
from pdfminer.pdfdocument import PDFDocument, PDFNoOutlines
from pdfminer.pdfpage import PDFPage
from pdfminer.pdfinterp import PDFResourceManager, PDFPageInterpreter
from pdfminer.converter import PDFPageAggregator
from pdfminer.layout import LAParams, LTTextBox, LTTextLine, LTFigure, LTImage, LTChar
def with_pdf (pdf_doc, fn, pdf_pwd, *args):
"""Open the pdf document, and apply the function, returning the results"""
result = None
# open the pdf file
fp = open(pdf_doc, 'rb')
# create a parser object associated with the file object
parser = PDFParser(fp)
# create a PDFDocument object that stores the document structure
doc = PDFDocument(parser)
# connect the parser and document objects
# supply the password for initialization
if doc.is_extractable:
# apply the function and return the result
result = fn(doc, *args)
# close the pdf file
except IOError:
# the file doesn't exist or similar problem
return result
### Table of Contents
def _parse_toc (doc):
"""With an open PDFDocument object, get the table of contents (toc) data
[this is a higher-order function to be passed to with_pdf()]"""
toc = []
outlines = doc.get_outlines()
for (level,title,dest,a,se) in outlines:
toc.append( (level, title) )
except PDFNoOutlines:
return toc
def get_toc (pdf_doc, pdf_pwd=''):
"""Return the table of contents (toc), if any, for this pdf file"""
return with_pdf(pdf_doc, _parse_toc, pdf_pwd)
### Extracting Images
def write_file (folder, filename, filedata, flags='w'):
"""Write the file data to the folder and filename combination
(flags: 'w' for write text, 'wb' for write binary, use 'a' instead of 'w' for append)"""
result = False
if os.path.isdir(folder):
file_obj = open(os.path.join(folder, filename), flags)
result = True
except IOError:
return result
def determine_image_type (stream_first_4_bytes):
"""Find out the image file type based on the magic number comparison of the first 4 (or 2) bytes"""
file_type = None
bytes_as_hex = b2a_hex(stream_first_4_bytes)
if bytes_as_hex.startswith('ffd8'):
file_type = '.jpeg'
elif bytes_as_hex == '89504e47':
file_type = '.png'
elif bytes_as_hex == '47494638':
file_type = '.gif'
elif bytes_as_hex.startswith('424d'):
file_type = '.bmp'
return file_type
def save_image (lt_image, page_number, images_folder):
"""Try to save the image data from this LTImage object, and return the file name, if successful"""
result = None
file_stream =
if file_stream:
file_ext = determine_image_type(file_stream[0:4])
if file_ext:
file_name = ''.join([str(page_number), '_',, file_ext])
if write_file(images_folder, file_name, file_stream, flags='wb'):
result = file_name
return result
### Extracting Text
def to_bytestring (s, enc='utf-8'):
"""Convert the given unicode string to a bytestring, using the standard encoding,
unless it's already a bytestring"""
if s:
if isinstance(s, str):
return s
return s.encode(enc)
def update_page_text_hash (h, lt_obj, pct=0.2):
"""Use the bbox x0,x1 values within pct% to produce lists of associated text within the hash"""
x0 = lt_obj.bbox[0]
x1 = lt_obj.bbox[2]
key_found = False
for k, v in h.items():
hash_x0 = k[0]
if x0 >= (hash_x0 * (1.0-pct)) and (hash_x0 * (1.0+pct)) >= x0:
hash_x1 = k[1]
if x1 >= (hash_x1 * (1.0-pct)) and (hash_x1 * (1.0+pct)) >= x1:
# the text inside this LT* object was positioned at the same
# width as a prior series of text, so it belongs together
key_found = True
h[k] = v
if not key_found:
# the text, based on width, is a new series,
# so it gets its own series (entry in the hash)
h[(x0,x1)] = [to_bytestring(lt_obj.get_text())]
return h
def parse_lt_objs (lt_objs, page_number, images_folder, text_content=None):
"""Iterate through the list of LT* objects and capture the text or image data contained in each"""
if text_content is None:
text_content = []
page_text = {} # k=(x0, x1) of the bbox, v=list of text strings within that bbox width (physical column)
for lt_obj in lt_objs:
if isinstance(lt_obj, LTTextBox) or isinstance(lt_obj, LTTextLine):
# text, so arrange is logically based on its column width
page_text = update_page_text_hash(page_text, lt_obj)
elif isinstance(lt_obj, LTImage):
# an image, so save it to the designated folder, and note its place in the text
saved_file = save_image(lt_obj, page_number, images_folder)
if saved_file:
# use html style <img /> tag to mark the position of the image within the text
text_content.append('<img src="'+os.path.join(images_folder, saved_file)+'" />')
print >> sys.stderr, "error saving image on page", page_number, lt_obj.__repr__
elif isinstance(lt_obj, LTFigure):
# LTFigure objects are containers for other LT* objects, so recurse through the children
text_content.append(parse_lt_objs(lt_obj, page_number, images_folder, text_content))
for k, v in sorted([(key,value) for (key,value) in page_text.items()]):
# sort the page_text hash by the keys (x0,x1 values of the bbox),
# which produces a top-down, left-to-right sequence of related columns
return '\n'.join(text_content)
### Processing Pages
def _parse_pages (doc, images_folder):
"""With an open PDFDocument object, get the pages and parse each one
[this is a higher-order function to be passed to with_pdf()]"""
rsrcmgr = PDFResourceManager()
laparams = LAParams()
device = PDFPageAggregator(rsrcmgr, laparams=laparams)
interpreter = PDFPageInterpreter(rsrcmgr, device)
text_content = []
for i, page in enumerate(PDFPage.create_pages(doc)):
# receive the LTPage object for this page
layout = device.get_result()
# layout is an LTPage object which may contain child objects like LTTextBox, LTFigure, LTImage, etc.
text_content.append(parse_lt_objs(layout, (i+1), images_folder))
return text_content
def get_pages (pdf_doc, pdf_pwd='', images_folder='/tmp'):
"""Process each of the pages in this pdf file and return a list of strings representing the text found in each page"""
return with_pdf(pdf_doc, _parse_pages, pdf_pwd, *tuple([images_folder]))