ENH: Validation to only allow positive integers for options

doc/source/whatsnew/v0.25.0.rst

@@ -1188,6 +1188,7 @@ Other
 - Allow :class:`Index` and :class:`RangeIndex` to be passed to numpy ``min`` and ``max`` functions (:issue:`26125`)
 - Use actual class name in repr of empty objects of a ``Series`` subclass (:issue:`27001`).
 - Bug in :class:`DataFrame` where passing an object array of timezone-aware `datetime` objects would incorrectly raise ``ValueError`` (:issue:`13287`)
+- Trying to set the display.precision, display.max_rows or display.max_columns options to anything but a None or a positive int will raise a ``ValueError`` (:issue:`23348`)
 
 .. _whatsnew_0.250.contributors:
 

pandas/_config/config.py

@@ -787,6 +787,7 @@ def is_instance_factory(_type):
                 ValueError if x is not an instance of `_type`
 
     """
+
     if isinstance(_type, (tuple, list)):
         _type = tuple(_type)
         type_repr = "|".join(map(str, _type))
@@ -820,6 +821,27 @@ def inner(x):
     return inner
 
 
+def is_pos_int(value):
+    """
+    Raises ValueError if type(x) is not equal to None or int, or if x is not
+    positive in the case of a int type.
+
+
+    Parameters
+    ----------
+    value - the value to be checked
+    """
+
+    if not (value is None or isinstance(value, int)):
+        msg = "Value must be an instance of <class 'NoneType'>|<class 'int'>"
+        raise ValueError(msg)
+
+    elif isinstance(value, int):
+        if value < 0:
+            msg = "int values must be positive for this option"
+            raise ValueError(msg)
+
+
 # common type validators, for convenience
 # usage: register_option(... , validator = is_int)
 is_int = is_type_factory(int)

pandas/core/config_init.py

@@ -18,6 +18,7 @@
     is_instance_factory,
     is_int,
     is_one_of_factory,
+    is_pos_int,
     is_text,
 )
 
@@ -319,7 +320,7 @@ def is_terminal():
 
 
 with cf.config_prefix("display"):
-    cf.register_option("precision", 6, pc_precision_doc, validator=is_int)
+    cf.register_option("precision", 6, pc_precision_doc, validator=is_pos_int)
     cf.register_option(
         "float_format",
         None,
@@ -333,12 +334,7 @@ def is_terminal():
         pc_max_info_rows_doc,
         validator=is_instance_factory((int, type(None))),
     )
-    cf.register_option(
-        "max_rows",
-        60,
-        pc_max_rows_doc,
-        validator=is_instance_factory([type(None), int]),
-    )
+    cf.register_option("max_rows", 60, pc_max_rows_doc, validator=is_pos_int)
     cf.register_option(
         "min_rows",
         10,
@@ -351,12 +347,7 @@ def is_terminal():
         max_cols = 0  # automatically determine optimal number of columns
     else:
         max_cols = 20  # cannot determine optimal number of columns
-    cf.register_option(
-        "max_columns",
-        max_cols,
-        pc_max_cols_doc,
-        validator=is_instance_factory([type(None), int]),
-    )
+    cf.register_option("max_columns", max_cols, pc_max_cols_doc, validator=is_pos_int)
     cf.register_option(
         "large_repr",
         "truncate",

pandas/tests/config/test_config.py

@@ -208,20 +208,33 @@ def test_set_option_multiple(self):
 
     def test_validation(self):
         self.cf.register_option("a", 1, "doc", validator=self.cf.is_int)
+        self.cf.register_option("d", 1, "doc", validator=self.cf.is_pos_int)
         self.cf.register_option("b.c", "hullo", "doc2", validator=self.cf.is_text)
+
         msg = "Value must have type '<class 'int'>'"
         with pytest.raises(ValueError, match=msg):
             self.cf.register_option("a.b.c.d2", "NO", "doc", validator=self.cf.is_int)
 
         self.cf.set_option("a", 2)  # int is_int
         self.cf.set_option("b.c", "wurld")  # str is_str
+        self.cf.set_option("d", 2)
 
         # None not is_int
         with pytest.raises(ValueError, match=msg):
             self.cf.set_option("a", None)
         with pytest.raises(ValueError, match=msg):
             self.cf.set_option("a", "ab")
 
+        msg = r"Value must be an instance of <class 'NoneType'>\|<class 'int'>"
+        with pytest.raises(ValueError, match=msg):
+            self.cf.register_option(
+                "a.b.c.d3", "NO", "doc", validator=self.cf.is_pos_int
+            )
+
+        msg = "int values must be positive for this option"
+        with pytest.raises(ValueError, match=msg):
+            self.cf.register_option("a.b.c.d3", -2, "doc", validator=self.cf.is_pos_int)
+
         msg = r"Value must be an instance of <class 'str'>\|<class 'bytes'>"
         with pytest.raises(ValueError, match=msg):
             self.cf.set_option("b.c", 1)