As stated in the PDF specification ISO 32000-1, table in Annex D.2 Latin Character Set and Encodings page 653 to 656 (available here: http://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/PDF32000_2008.pdf):
"The SPACE character shall also be encoded as 312 in MacRomanEncoding and as 240 in WinAnsiEncoding. This duplicate code shall signify a nonbreaking space; it shall be typographically the same as (U+003A) SPACE."
The duplicate key was missing, therefore PDFMiner was returning the string "(cid:160)".
This fix adds the duplicate key in latin_enc.py
glyphlist.py does not need to be modified as it already contains a key for non breaking space https://github.com/lucanaso/pdfminer/blob/master/pdfminer/glyphlist.py#L2755.
This commit finds horizontal neighbors in a horizonal line and merges them together into a single horizontal line if necessary. This leads to much better text extraction if the PDF was created in a funky way.
For example (test case coming), I have seen PDFs which are written almost like vertical columns, but the text is entirely horizontal.
1.
When detecting text in a horizontal line, we already add a space between words if separated by more than word_margin apart. However now, we only do it if there is not already an existing space. This prevents multiple spaces being placed between words.
2.
Detect a horizontal line if the line is zero width. This improves our detection of horizonal lines when looking for both horizontal and vertical.
3.
Don't detect a vertical line if the previous letter is whitspace. Prevents double spaces being caught as vert lines.
4.
Improve upon an unfortunate O(N^2) algorithm which I have seen taking many minutes to execute. Unfortunately, while the "fix" reduces algorithmic complexity, it isn't technically correct, so we only do it when we know things will take a long time.