475 lines
16 KiB
Python
475 lines
16 KiB
Python
# -*- coding: utf-8 -*-
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from __future__ import division
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import os
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import logging
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import warnings
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import numpy as np
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import pandas as pd
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from .base import BaseParser
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from ..core import TextEdges
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from ..utils import (text_in_bbox, compute_accuracy,
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compute_whitespace)
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logger = logging.getLogger("camelot")
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class Stream(BaseParser):
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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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split_text=split_text,
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strip_text=strip_text,
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flag_size=flag_size,
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)
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self.columns = columns
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self._validate_columns()
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self.edge_tol = edge_tol
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self.row_tol = row_tol
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self.column_tol = column_tol
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@staticmethod
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def _text_bbox(t_bbox):
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"""Returns bounding box for the text present on a page.
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Parameters
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----------
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t_bbox : dict
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Dict with two keys 'horizontal' and 'vertical' with lists of
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LTTextLineHorizontals and LTTextLineVerticals respectively.
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Returns
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-------
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text_bbox : tuple
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Tuple (x0, y0, x1, y1) in pdf coordinate space.
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"""
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xmin = min(t.x0 for direction in t_bbox for t in t_bbox[direction])
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ymin = min(t.y0 for direction in t_bbox for t in t_bbox[direction])
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xmax = max(t.x1 for direction in t_bbox for t in t_bbox[direction])
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ymax = max(t.y1 for direction in t_bbox for t in t_bbox[direction])
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text_bbox = (xmin, ymin, xmax, ymax)
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return text_bbox
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@staticmethod
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def _group_rows(text, row_tol=2):
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"""Groups PDFMiner text objects into rows vertically
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within a tolerance.
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Parameters
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----------
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text : list
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List of PDFMiner text objects.
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row_tol : int, optional (default: 2)
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Returns
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-------
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rows : list
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Two-dimensional list of text objects grouped into rows.
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"""
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row_y = None
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rows = []
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temp = []
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non_empty_text = [t for t in text if t.get_text().strip()]
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for t in non_empty_text:
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# is checking for upright necessary?
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# if t.get_text().strip() and all([obj.upright \
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# for obj in t._objs
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# if type(obj) is LTChar]):
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if row_y is None:
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row_y = t.y0
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elif not np.isclose(row_y, t.y0, atol=row_tol):
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rows.append(sorted(temp, key=lambda t: t.x0))
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temp = []
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# We update the row's bottom as we go, to be forgiving if there
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# is a gradual change across multiple columns.
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row_y = t.y0
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temp.append(t)
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rows.append(sorted(temp, key=lambda t: t.x0))
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return rows
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@staticmethod
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def _merge_columns(l, column_tol=0):
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"""Merges column boundaries horizontally if they overlap
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or lie within a tolerance.
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Parameters
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----------
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l : list
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List of column x-coordinate tuples.
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column_tol : int, optional (default: 0)
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Returns
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-------
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merged : list
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List of merged column x-coordinate tuples.
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"""
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merged = []
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for higher in l:
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if not merged:
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merged.append(higher)
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else:
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lower = merged[-1]
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if column_tol >= 0:
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if higher[0] <= lower[1] or np.isclose(
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higher[0], lower[1], atol=column_tol
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):
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upper_bound = max(lower[1], higher[1])
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lower_bound = min(lower[0], higher[0])
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merged[-1] = (lower_bound, upper_bound)
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else:
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merged.append(higher)
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elif column_tol < 0:
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if higher[0] <= lower[1]:
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if np.isclose(higher[0], lower[1],
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atol=abs(column_tol)):
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merged.append(higher)
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else:
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upper_bound = max(lower[1], higher[1])
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lower_bound = min(lower[0], higher[0])
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merged[-1] = (lower_bound, upper_bound)
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else:
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merged.append(higher)
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return merged
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@staticmethod
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def _join_rows(rows_grouped, text_y_max, text_y_min):
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"""Makes row coordinates continuous. For the row to "touch"
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we split the existing gap between them in half.
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Parameters
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----------
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rows_grouped : list
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Two-dimensional list of text objects grouped into rows.
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text_y_max : int
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text_y_min : int
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Returns
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-------
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rows : list
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List of continuous row y-coordinate tuples.
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"""
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row_boundaries = [
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[
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max(t.y1 for t in r),
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min(t.y0 for t in r)
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]
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for r in rows_grouped
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]
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for i in range(0, len(row_boundaries)-1):
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top_row = row_boundaries[i]
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bottom_row = row_boundaries[i+1]
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top_row[1] = bottom_row[0] = (top_row[1] + bottom_row[0]) / 2
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row_boundaries[0][0] = text_y_max
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row_boundaries[-1][1] = text_y_min
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return row_boundaries
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@staticmethod
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def _add_columns(cols, text, row_tol):
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"""Adds columns to existing list by taking into account
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the text that lies outside the current column x-coordinates.
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Parameters
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----------
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cols : list
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List of column x-coordinate tuples.
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text : list
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List of PDFMiner text objects.
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ytol : int
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Returns
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-------
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cols : list
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Updated list of column x-coordinate tuples.
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"""
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if text:
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text = Stream._group_rows(text, row_tol=row_tol)
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elements = [len(r) for r in text]
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new_cols = [
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(t.x0, t.x1)
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for r in text if len(r) == max(elements)
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for t in r
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]
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cols.extend(Stream._merge_columns(sorted(new_cols)))
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return cols
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@staticmethod
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def _join_columns(cols, text_x_min, text_x_max):
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"""Makes column coordinates continuous.
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Parameters
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----------
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cols : list
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List of column x-coordinate tuples.
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text_x_min : int
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text_y_max : int
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Returns
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-------
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cols : list
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Updated list of column x-coordinate tuples.
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"""
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cols = sorted(cols)
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cols = [(cols[i][0] + cols[i - 1][1]) / 2 for i in range(1, len(cols))]
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cols.insert(0, text_x_min)
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cols.append(text_x_max)
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cols = [(cols[i], cols[i + 1]) for i in range(0, len(cols) - 1)]
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return cols
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def _validate_columns(self):
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if self.table_areas is not None and self.columns is not None:
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if len(self.table_areas) != len(self.columns):
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raise ValueError("Length of table_areas and columns"
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" should be equal")
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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 _generate_table_bbox(self):
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self.textedges = []
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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 in self.table_regions:
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x1, y1, x2, y2 = region.split(",")
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x1 = float(x1)
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y1 = float(y1)
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x2 = float(x2)
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y2 = float(y2)
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region_text = text_in_bbox(
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(x1, y2, x2, y1), 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 in self.table_areas:
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x1, y1, x2, y2 = area.split(",")
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x1 = float(x1)
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y1 = float(y1)
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x2 = float(x2)
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y2 = float(y2)
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table_bbox[(x1, y2, x2, y1)] = None
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self.table_bbox = table_bbox
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def _generate_columns_and_rows(self, table_idx, tk):
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# select elements which lie within table_bbox
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t_bbox = {}
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t_bbox["horizontal"] = text_in_bbox(tk, self.horizontal_text)
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t_bbox["vertical"] = text_in_bbox(tk, self.vertical_text)
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t_bbox["horizontal"].sort(key=lambda x: (-x.y0, x.x0))
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t_bbox["vertical"].sort(key=lambda x: (x.x0, -x.y0))
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self.t_bbox = t_bbox
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text_x_min, text_y_min, text_x_max, text_y_max = \
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self._text_bbox(self.t_bbox)
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rows_grouped = self._group_rows(
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self.t_bbox["horizontal"], row_tol=self.row_tol)
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rows = self._join_rows(rows_grouped, text_y_max, text_y_min)
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elements = [len(r) for r in rows_grouped]
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if self.columns is not None and self.columns[table_idx] != "":
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# user has to input boundary columns too
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# take (0, pdf_width) by default
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# similar to else condition
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# len can't be 1
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cols = self.columns[table_idx].split(",")
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cols = [float(c) for c in cols]
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cols.insert(0, text_x_min)
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cols.append(text_x_max)
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cols = [(cols[i], cols[i + 1]) for i in range(0, len(cols) - 1)]
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else:
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# calculate mode of the list of number of elements in
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# each row to guess the number of columns
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ncols = max(set(elements), key=elements.count)
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if ncols == 1:
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# if mode is 1, the page usually contains not tables
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# but there can be cases where the list can be skewed,
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# try to remove all 1s from list in this case and
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# see if the list contains elements, if yes, then use
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# the mode after removing 1s
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elements = list(filter(lambda x: x != 1, elements))
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if elements:
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ncols = max(set(elements), key=elements.count)
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else:
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warnings.warn(
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"No tables found in table area {}"
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.format(table_idx + 1)
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)
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cols = [
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(t.x0, t.x1)
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for r in rows_grouped
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if len(r) == ncols
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for t in r
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]
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cols = self._merge_columns(
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sorted(cols),
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column_tol=self.column_tol
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)
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inner_text = []
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for i in range(1, len(cols)):
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left = cols[i - 1][1]
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right = cols[i][0]
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inner_text.extend(
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[
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t
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for direction in self.t_bbox
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for t in self.t_bbox[direction]
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if t.x0 > left and t.x1 < right
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]
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)
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outer_text = [
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t
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for direction in self.t_bbox
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for t in self.t_bbox[direction]
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if t.x0 > cols[-1][1] or t.x1 < cols[0][0]
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]
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inner_text.extend(outer_text)
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cols = self._add_columns(cols, inner_text, self.row_tol)
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cols = self._join_columns(cols, text_x_min, text_x_max)
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return cols, rows
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def _generate_table(self, table_idx, cols, rows, **kwargs):
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table = self._initialize_new_table(table_idx, cols, rows)
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table = table.set_all_edges()
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pos_errors = self._compute_parse_errors(table)
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accuracy = compute_accuracy([[100, pos_errors]])
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table.record_parse_metadata(self)
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table.accuracy = accuracy
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# for plotting
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_text = []
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_text.extend([(t.x0, t.y0, t.x1, t.y1) for t in self.horizontal_text])
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_text.extend([(t.x0, t.y0, t.x1, t.y1) for t in self.vertical_text])
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table._text = _text
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table._bbox = self.table_bbox
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table._segments = None
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table._textedges = self.textedges
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return table
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def extract_tables(self, filename, suppress_stdout=False):
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if not suppress_stdout:
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logger.info("Processing {}".format(
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os.path.basename(self.rootname)))
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if not self.horizontal_text:
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if self.images:
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warnings.warn(
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"{} is image-based, camelot only works on"
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" text-based pages.".format(
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os.path.basename(self.rootname))
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)
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else:
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warnings.warn(
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"No tables found on {}".format(
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os.path.basename(self.rootname))
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)
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return []
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# Identify plausible areas within the doc where tables lie,
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# populate table_bbox keys with these areas.
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self._generate_table_bbox()
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_tables = []
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# sort tables based on y-coord
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for table_idx, tk in enumerate(
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sorted(self.table_bbox.keys(), key=lambda x: x[1], reverse=True)
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):
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cols, rows = self._generate_columns_and_rows(table_idx, tk)
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table = self._generate_table(table_idx, cols, rows)
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table._bbox = tk
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_tables.append(table)
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return _tables
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