Fix bug that crashed table extraction when null value provided for (text|intersection)_(x|y)_tolerance keys

Fixes #539
Thanks to @yoavxyoav for reporting

CHANGELOG.md

@@ -15,6 +15,7 @@ All notable changes to this project will be documented in this file. The format
 ### Fixed
 - Fix slowdown in `.extract_words(...)`/`WordExtractor.iter_chars_to_words(...)` on very long words, caused by repeatedly re-calculating bounding box. ([#483](https://github.com/jsvine/pdfplumber/discussions/483))
 - Handle `UnicodeDecodeError` when trying to decode utf-16-encoded annotations ([#463](https://github.com/jsvine/pdfplumber/issues/463)) [h/t @tungph]
+- Fix crash when extracting tables with null values in `(text|intersection)_(x|y)_tolerance` settings. ([#539](https://github.com/jsvine/pdfplumber/discussions/539)) [h/t @yoavxyoav]
 
 ### Development Changes
 - Add `CONTRIBUTING.md` ([#428](https://github.com/jsvine/pdfplumber/pull/428))

pdfplumber/page.py

@@ -219,6 +219,7 @@ class Page(Container):
         return TableFinder(self, table_settings).tables
 
     def extract_tables(self, table_settings={}):
+        table_settings = TableFinder.resolve_table_settings(table_settings)
         tables = self.find_tables(table_settings)
 
         extract_kwargs = dict(
@@ -230,6 +231,7 @@ class Page(Container):
         return [table.extract(**extract_kwargs) for table in tables]
 
     def extract_table(self, table_settings={}):
+        table_settings = TableFinder.resolve_table_settings(table_settings)
         tables = self.find_tables(table_settings)
 
         if len(tables) == 0:

pdfplumber/table.py

@@ -438,20 +438,8 @@ class TableFinder(object):
     """
 
     def __init__(self, page, settings={}):
-        for k in settings.keys():
-            if k not in DEFAULT_TABLE_SETTINGS:
-                raise ValueError(f"Unrecognized table setting: '{k}'")
         self.page = page
-        self.settings = dict(DEFAULT_TABLE_SETTINGS)
-        self.settings.update(settings)
-        for var, fallback in [
-            ("text_x_tolerance", "text_tolerance"),
-            ("text_y_tolerance", "text_tolerance"),
-            ("intersection_x_tolerance", "intersection_tolerance"),
-            ("intersection_y_tolerance", "intersection_tolerance"),
-        ]:
-            if self.settings[var] is None:
-                self.settings.update({var: self.settings[fallback]})
+        self.settings = self.resolve_table_settings(settings)
         self.edges = self.get_edges()
         self.intersections = edges_to_intersections(
             self.edges,
@@ -461,6 +449,40 @@ class TableFinder(object):
         self.cells = intersections_to_cells(self.intersections)
         self.tables = [Table(self.page, t) for t in cells_to_tables(self.cells)]
 
+    @staticmethod
+    def resolve_table_settings(table_settings={}):
+        """Clean up user-provided table settings.
+
+        Validates that the table settings provided consists of acceptable keys and
+        returns a cleaned up version. The cleaned up version fills out the missing
+        values with the default values in the provided settings.
+
+        TODO: Can be further used to validate that the values are of the correct
+            type. For example, raising a value error when a non-boolean input is
+            provided for the key ``keep_blank_chars``.
+
+        :param table_settings: User-provided table settings.
+        :returns: A cleaned up version of the user-provided table settings.
+        :raises ValueError: When an unrecognised key is provided.
+        """
+        for k in table_settings.keys():
+            if k not in DEFAULT_TABLE_SETTINGS:
+                raise ValueError(f"Unrecognized table setting: '{k}'")
+
+        resolved_table_settings = dict(DEFAULT_TABLE_SETTINGS)
+        resolved_table_settings.update(table_settings)
+
+        for var, fallback in [
+            ("text_x_tolerance", "text_tolerance"),
+            ("text_y_tolerance", "text_tolerance"),
+            ("intersection_x_tolerance", "intersection_tolerance"),
+            ("intersection_y_tolerance", "intersection_tolerance"),
+        ]:
+            if resolved_table_settings[var] is None:
+                resolved_table_settings.update({var: resolved_table_settings[fallback]})
+
+        return resolved_table_settings
+
     def get_edges(self):
         settings = self.settings
         for name in ["vertical", "horizontal"]:

tests/test_table.py

@@ -170,3 +170,31 @@ class Test(unittest.TestCase):
                 # Verify that all cell contain real data
                 for cell in t[3]:
                     assert "last" in cell
+
+    def test_discussion_539_null_value(self):
+        """
+        See discussion #539
+        """
+        path = os.path.join(HERE, "pdfs/nics-background-checks-2015-11.pdf")
+        with pdfplumber.open(path) as pdf:
+            page = pdf.pages[0]
+            table_settings = {
+                "vertical_strategy": "lines",
+                "horizontal_strategy": "lines",
+                "explicit_vertical_lines": [],
+                "explicit_horizontal_lines": [],
+                "snap_tolerance": 3,
+                "join_tolerance": 3,
+                "edge_min_length": 3,
+                "min_words_vertical": 3,
+                "min_words_horizontal": 1,
+                "keep_blank_chars": False,
+                "text_tolerance": 3,
+                "text_x_tolerance": None,
+                "text_y_tolerance": None,
+                "intersection_tolerance": 3,
+                "intersection_x_tolerance": None,
+                "intersection_y_tolerance": None,
+            }
+            assert page.extract_table(table_settings)
+            assert page.extract_tables(table_settings)