如何使用 PDFMiner 从 pdf 中提取表格？

Question

我正在尝试从 pdf 文档中的某些表格中提取信息。
考虑输入：

Title 1
some text some text some text some text some text
some text some text some text some text some text

Table Title
| Col1          | Col2    | Col3    |
|---------------|---------|---------|
| val11         | val12   | val13   |
| val21         | val22   | val23   |
| val31         | val32   | val33   |

Title 2
some more text some more text some more text some more text
some more text
some more text some more text some more text some more text

我可以得到这样的大纲/标题：

path='myFile.pdf'
# Open a PDF file.
fp = open(path, 'rb')
# Create a PDF parser object associated with the file object.
parser = PDFParser(fp)
# Create a PDF document object that stores the document structure.
# Supply the password for initialization.
document = PDFDocument(parser, '')
outlines = document.get_outlines()
for (level,title,dest,a,se) in outlines:
    print (level, title)

这给了我：

path='myFile.pdf'
# Open a PDF file.
fp = open(path, 'rb')
# Create a PDF parser object associated with the file object.
parser = PDFParser(fp)
# Create a PDF document object that stores the document structure.
# Supply the password for initialization.
document = PDFDocument(parser, '')
outlines = document.get_outlines()
for (level,title,dest,a,se) in outlines:
    print (level, title)

这是完美的，因为级别与文本层次结构一致。现在我可以提取文本如下：

if not document.is_extractable:
    raise PDFTextExtractionNotAllowed
# Create a PDF resource manager object that stores shared resources.
rsrcmgr = PDFResourceManager()
# Create a PDF device object.
laparams = LAParams()
device = PDFPageAggregator(rsrcmgr, laparams=laparams)
# Create a PDF interpreter object.
interpreter = PDFPageInterpreter(rsrcmgr, device)
# Process each page contained in the document.
text_from_pdf = open('textFromPdf.txt','w')
for page in PDFPage.create_pages(document):
    interpreter.process_page(page)
    layout = device.get_result()
    for element in layout:
        if isinstance(element, LTTextBox):
            text_from_pdf.write(''.join([i if ord(i) < 128 else ' '
                                            for i in element.get_text()]))

这给了我：

(1, u'Title 1')
(2, u'Table Title')
(1, u'Title 2')

这有点奇怪，因为表是按列方式提取的。我可以逐行获取表格吗？此外，如何确定表格的开始和结束位置？

Answer 1

如果您只想从 PDF 文档中提取表格，请查看这个答案：How to extract table as text from the PDF using Python?

从这个答案中，我尝试了tabula-py，它对我有用，可以处理分布在多页 PDF 上的图表。tabula-py 正确地跳过了所有页眉和页脚。之前我曾在同一类型的文档上尝试过 PDFMiner，并且遇到了您提到的相同问题，有时甚至更糟。