128 lines
4.5 KiB
Python
128 lines
4.5 KiB
Python
# -*- coding: utf-8 -*-
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from __future__ import division
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from .base import TextBaseParser
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from ..core import TextEdges
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from ..utils import (
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bbox_from_str,
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text_in_bbox
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)
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class Stream(TextBaseParser):
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"""Stream method of parsing looks for spaces between text
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to parse the table.
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If you want to specify columns when specifying multiple table
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areas, make sure that the length of both lists are equal.
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Parameters
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----------
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table_regions : list, optional (default: None)
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List of page regions that may contain tables of the form x1,y1,x2,y2
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where (x1, y1) -> left-top and (x2, y2) -> right-bottom
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in PDF coordinate space.
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table_areas : list, optional (default: None)
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List of table area strings of the form x1,y1,x2,y2
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where (x1, y1) -> left-top and (x2, y2) -> right-bottom
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in PDF coordinate space.
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columns : list, optional (default: None)
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List of column x-coordinates strings where the coordinates
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are comma-separated.
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split_text : bool, optional (default: False)
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Split text that spans across multiple cells.
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flag_size : bool, optional (default: False)
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Flag text based on font size. Useful to detect
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super/subscripts. Adds <s></s> around flagged text.
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strip_text : str, optional (default: '')
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Characters that should be stripped from a string before
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assigning it to a cell.
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edge_tol : int, optional (default: 50)
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Tolerance parameter for extending textedges vertically.
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row_tol : int, optional (default: 2)
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Tolerance parameter used to combine text vertically,
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to generate rows.
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column_tol : int, optional (default: 0)
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Tolerance parameter used to combine text horizontally,
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to generate columns.
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"""
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def __init__(
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self,
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table_regions=None,
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table_areas=None,
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columns=None,
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flag_size=False,
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split_text=False,
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strip_text="",
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edge_tol=50,
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row_tol=2,
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column_tol=0,
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**kwargs
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):
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super().__init__(
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"stream",
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table_regions=table_regions,
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table_areas=table_areas,
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columns=columns,
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flag_size=flag_size,
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split_text=split_text,
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strip_text=strip_text,
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edge_tol=edge_tol,
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row_tol=row_tol,
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column_tol=column_tol,
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)
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self.textedges = []
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def _nurminen_table_detection(self, textlines):
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"""A general implementation of the table detection algorithm
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described by Anssi Nurminen's master's thesis.
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Link: https://dspace.cc.tut.fi/dpub/bitstream/handle/123456789/21520/Nurminen.pdf?sequence=3 # noqa
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Assumes that tables are situated relatively far apart
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vertically.
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"""
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# TODO: add support for arabic text #141
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# sort textlines in reading order
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textlines.sort(key=lambda x: (-x.y0, x.x0))
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textedges = TextEdges(edge_tol=self.edge_tol)
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# generate left, middle and right textedges
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textedges.generate(textlines)
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# select relevant edges
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relevant_textedges = textedges.get_relevant()
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self.textedges.extend(relevant_textedges)
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# guess table areas using textlines and relevant edges
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table_bbox = textedges.get_table_areas(textlines, relevant_textedges)
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# treat whole page as table area if no table areas found
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if not table_bbox:
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table_bbox = {(0, 0, self.pdf_width, self.pdf_height): None}
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return table_bbox
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def record_parse_metadata(self, table):
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"""Record data about the origin of the table
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"""
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super().record_parse_metadata(table)
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table._textedges = self.textedges
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def _generate_table_bbox(self):
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if self.table_areas is None:
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hor_text = self.horizontal_text
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if self.table_regions is not None:
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# filter horizontal text
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hor_text = []
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for region_str in self.table_regions:
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region_text = text_in_bbox(
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bbox_from_str(region_str),
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self.horizontal_text)
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hor_text.extend(region_text)
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# find tables based on nurminen's detection algorithm
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table_bbox = self._nurminen_table_detection(hor_text)
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else:
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table_bbox = {}
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for area_str in self.table_areas:
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table_bbox[bbox_from_str(area_str)] = None
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self.table_bbox = table_bbox
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