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Updated extractor/README

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Peter Williams 2020-06-22 17:56:32 +10:00
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extractor/README.md
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@ -1,9 +1,6 @@
TEXT EXTRACTION CODE
====================
BASIC IDEAS
-----------
There are two [directions](https://www.w3.org/International/questions/qa-scripts.en#directions)s\.
- *reading*
@ -13,18 +10,6 @@ In English text,
- the *reading* direction is left to right, increasing X in the PDF coordinate system.
- the *depth* directon is top to bottom, decreasing Y in the PDF coordinate system.
*depth* is the distance from the bottom of a word's bounding box from the top of the page.
depth := pageSize.Ury - r.Lly
* Pages are divided into rectangular regions called `textPara`s.
* The `textPara`s in a page are sorted in reading order (the order they are read in, not the
*reading* direction above).
* Each `textPara` contains `textLine`s, lines with the `textPara`'s bounding box.
* Each `textLine` has extracted for the line in its `text()` function.
* Page text is extracted by iterating over `textPara`s and within each `textPara` iterating over its
`textLine`s.
* The textMarks corresponding to extracted text can be found.
HOW TEXT IS EXTRACTED
---------------------
@ -36,13 +21,13 @@ HOW TEXT IS EXTRACTED
and spltting on space characters and the gaps between marks.
* The `textWords`s are grouped into `textParas`s based on their bounding boxes' proximities to other
textWords.
* The textWords in each textPara are arranged into textLines (textWords of similar depths).
* With each textLine, textWords are sorted in reading order each one that starts a whole word is marked.
See textLine.text()
* textPara.writeCellText() shows how to extract the paragraph text from this arrangment.
* The `textWord`s in each `textPara` are arranged into `textLine`s (`textWord`s of similar depth).
* Within each `textLine`, `textWord`s are sorted in reading order each one that starts a whole word is marked.
See `textLine.text()`.
* `textPara.writeCellText()` shows how to extract the paragraph text from this arrangment.
* All the `textPara`s on a page are checked to see if they are arranged as cells within a table and,
if they are, they are combined into `textTable`s and a textPara containing the textTable replaces the
the textParas containing the cells.
the `textPara`s containing the cells.
* The textParas, some of which may be tables, in sorted into reading order (the order in which they
are reading, not in the reading directions).
@ -61,9 +46,12 @@ of about the same depth sorted left to right.
* textLine.markWordBoundaries() marks the textWords in each textLine that start whole words.
TODO
====
Remove serial code????
Reinstate rotated text handling.
Reinstate hyphen diacritic composition.
Reinstate duplicate text removal
-----
* Remove serial code????
* Remove verbose* logginng?
* Reinstate rotated text handling.
* Reinstate diacritic composition.
* Reinstate duplicate text removal.
* Reinstate creater_test.go extraction test.