CLN: change str.format() to f-string

pandas/core/arrays/string_.py

@@ -171,7 +171,7 @@ def _validate(self):
         if self._ndarray.dtype != "object":
             raise ValueError(
                 "StringArray requires a sequence of strings. Got "
-                "'{}' dtype instead.".format(self._ndarray.dtype)
+                f"'{self._ndarray.dtype}' dtype instead."
             )
 
     @classmethod
@@ -222,7 +222,7 @@ def __setitem__(self, key, value):
                 value = StringDtype.na_value
             elif not isinstance(value, str):
                 raise ValueError(
-                    "Cannot set non-string value '{}' into a StringArray.".format(value)
+                    f"Cannot set non-string value '{value}' into a StringArray."
                 )
         else:
             if not is_array_like(value):
@@ -245,7 +245,7 @@ def astype(self, dtype, copy=True):
         return super().astype(dtype, copy)
 
     def _reduce(self, name, skipna=True, **kwargs):
-        raise TypeError("Cannot perform reduction '{}' with string dtype".format(name))
+        raise TypeError(f"Cannot perform reduction '{name}' with string dtype")
 
     def value_counts(self, dropna=False):
         from pandas import value_counts
@@ -269,9 +269,7 @@ def method(self, other):
                 if len(other) != len(self):
                     # prevent improper broadcasting when other is 2D
                     raise ValueError(
-                        "Lengths of operands do not match: {} != {}".format(
-                            len(self), len(other)
-                        )
+                        f"Lengths of operands do not match: {len(self)} != {len(other)}"
                     )
 
                 other = np.asarray(other)
@@ -287,7 +285,7 @@ def method(self, other):
                 dtype = "object" if mask.any() else "bool"
                 return np.asarray(result, dtype=dtype)
 
-        return compat.set_function_name(method, "__{}__".format(op.__name__), cls)
+        return compat.set_function_name(method, f"__{op.__name__}__", cls)
 
     @classmethod
     def _add_arithmetic_ops(cls):

pandas/core/arrays/timedeltas.py

@@ -70,15 +70,15 @@ def f(self):
         return result
 
     f.__name__ = name
-    f.__doc__ = "\n{}\n".format(docstring)
+    f.__doc__ = f"\n{docstring}\n"
     return property(f)
 
 
 def _td_array_cmp(cls, op):
     """
     Wrap comparison operations to convert timedelta-like to timedelta64
     """
-    opname = "__{name}__".format(name=op.__name__)
+    opname = f"__{op.__name__}__"
     nat_result = opname == "__ne__"
 
     @unpack_zerodim_and_defer(opname)
@@ -215,10 +215,10 @@ def __init__(self, values, dtype=_TD_DTYPE, freq=None, copy=False):
 
         if not isinstance(values, np.ndarray):
             msg = (
-                "Unexpected type '{}'. 'values' must be a TimedeltaArray "
-                "ndarray, or Series or Index containing one of those."
+                f"Unexpected type '{type(values).__name__}'. 'values' must be a"
+                " TimedeltaArray ndarray, or Series or Index containing one of those."
             )
-            raise ValueError(msg.format(type(values).__name__))
+            raise ValueError(msg)
         if values.ndim != 1:
             raise ValueError("Only 1-dimensional input arrays are supported.")
 
@@ -351,10 +351,7 @@ def _validate_fill_value(self, fill_value):
         elif isinstance(fill_value, (timedelta, np.timedelta64, Tick)):
             fill_value = Timedelta(fill_value).value
         else:
-            raise ValueError(
-                "'fill_value' should be a Timedelta. "
-                "Got '{got}'.".format(got=fill_value)
-            )
+            raise ValueError(f"'fill_value' should be a Timedelta. Got '{fill_value}'.")
         return fill_value
 
     def astype(self, dtype, copy=True):
@@ -461,9 +458,7 @@ def _format_native_types(self, na_rep="NaT", date_format=None):
     def _add_offset(self, other):
         assert not isinstance(other, Tick)
         raise TypeError(
-            "cannot add the type {typ} to a {cls}".format(
-                typ=type(other).__name__, cls=type(self).__name__
-            )
+            f"cannot add the type {type(other).__name__} to a {type(self).__name__}"
         )
 
     def _add_delta(self, delta):
@@ -523,9 +518,7 @@ def _addsub_offset_array(self, other, op):
             return super()._addsub_offset_array(other, op)
         except AttributeError:
             raise TypeError(
-                "Cannot add/subtract non-tick DateOffset to {cls}".format(
-                    cls=type(self).__name__
-                )
+                f"Cannot add/subtract non-tick DateOffset to {type(self).__name__}"
             )
 
     def __mul__(self, other):
@@ -634,9 +627,7 @@ def __rtruediv__(self, other):
 
         elif lib.is_scalar(other):
             raise TypeError(
-                "Cannot divide {typ} by {cls}".format(
-                    typ=type(other).__name__, cls=type(self).__name__
-                )
+                f"Cannot divide {type(other).__name__} by {type(self).__name__}"
             )
 
         if not hasattr(other, "dtype"):
@@ -659,9 +650,7 @@ def __rtruediv__(self, other):
 
         else:
             raise TypeError(
-                "Cannot divide {dtype} data by {cls}".format(
-                    dtype=other.dtype, cls=type(self).__name__
-                )
+                f"Cannot divide {other.dtype} data by {type(self).__name__}"
             )
 
     def __floordiv__(self, other):
@@ -724,11 +713,7 @@ def __floordiv__(self, other):
 
         else:
             dtype = getattr(other, "dtype", type(other).__name__)
-            raise TypeError(
-                "Cannot divide {typ} by {cls}".format(
-                    typ=dtype, cls=type(self).__name__
-                )
-            )
+            raise TypeError(f"Cannot divide {dtype} by {type(self).__name__}")
 
     def __rfloordiv__(self, other):
         if isinstance(other, (ABCSeries, ABCDataFrame, ABCIndexClass)):
@@ -749,9 +734,7 @@ def __rfloordiv__(self, other):
                 return result
 
             raise TypeError(
-                "Cannot divide {typ} by {cls}".format(
-                    typ=type(other).__name__, cls=type(self).__name__
-                )
+                f"Cannot divide {type(other).__name__} by {type(self).__name__}"
             )
 
         if not hasattr(other, "dtype"):
@@ -779,11 +762,7 @@ def __rfloordiv__(self, other):
 
         else:
             dtype = getattr(other, "dtype", type(other).__name__)
-            raise TypeError(
-                "Cannot divide {typ} by {cls}".format(
-                    typ=dtype, cls=type(self).__name__
-                )
-            )
+            raise TypeError(f"Cannot divide {dtype} by {type(self).__name__}")
 
     def __mod__(self, other):
         # Note: This is a naive implementation, can likely be optimized
@@ -1056,11 +1035,7 @@ def sequence_to_td64ns(data, copy=False, unit="ns", errors="raise"):
 
     else:
         # This includes datetime64-dtype, see GH#23539, GH#29794
-        raise TypeError(
-            "dtype {dtype} cannot be converted to timedelta64[ns]".format(
-                dtype=data.dtype
-            )
-        )
+        raise TypeError(f"dtype {data.dtype} cannot be converted to timedelta64[ns]")
 
     data = np.array(data, copy=copy)
     if data.ndim != 1:
@@ -1096,7 +1071,7 @@ def ints_to_td64ns(data, unit="ns"):
         copy_made = True
 
     if unit != "ns":
-        dtype_str = "timedelta64[{unit}]".format(unit=unit)
+        dtype_str = f"timedelta64[{unit}]"
         data = data.view(dtype_str)
 
         # TODO: watch out for overflows when converting from lower-resolution

pandas/core/common.py

@@ -388,7 +388,7 @@ def standardize_mapping(into):
             return partial(collections.defaultdict, into.default_factory)
         into = type(into)
     if not issubclass(into, abc.Mapping):
-        raise TypeError("unsupported type: {into}".format(into=into))
+        raise TypeError(f"unsupported type: {into}")
     elif into == collections.defaultdict:
         raise TypeError("to_dict() only accepts initialized defaultdicts")
     return into

pandas/core/computation/engines.py

@@ -31,8 +31,7 @@ def _check_ne_builtin_clash(expr):
     if overlap:
         s = ", ".join(repr(x) for x in overlap)
         raise NumExprClobberingError(
-            'Variables in expression "{expr}" '
-            "overlap with builtins: ({s})".format(expr=expr, s=s)
+            f'Variables in expression "{expr}" overlap with builtins: ({s})'
         )
 
 

pandas/core/computation/expr.py

@@ -282,10 +282,9 @@ def _filter_nodes(superclass, all_nodes=_all_nodes):
 # and we don't want `stmt` and friends in their so get only the class whose
 # names are capitalized
 _base_supported_nodes = (_all_node_names - _unsupported_nodes) | _hacked_nodes
-_msg = "cannot both support and not support {intersection}".format(
-    intersection=_unsupported_nodes & _base_supported_nodes
-)
-assert not _unsupported_nodes & _base_supported_nodes, _msg
+intersection = _unsupported_nodes & _base_supported_nodes
+_msg = f"cannot both support and not support {intersection}"
+assert not intersection, _msg
 
 
 def _node_not_implemented(node_name, cls):
@@ -312,7 +311,7 @@ def disallowed(cls):
         cls.unsupported_nodes = ()
         for node in nodes:
             new_method = _node_not_implemented(node, cls)
-            name = "visit_{node}".format(node=node)
+            name = f"visit_{node}"
             cls.unsupported_nodes += (name,)
             setattr(cls, name, new_method)
         return cls
@@ -349,13 +348,13 @@ def add_ops(op_classes):
 
     def f(cls):
         for op_attr_name, op_class in op_classes.items():
-            ops = getattr(cls, "{name}_ops".format(name=op_attr_name))
-            ops_map = getattr(cls, "{name}_op_nodes_map".format(name=op_attr_name))
+            ops = getattr(cls, f"{op_attr_name}_ops")
+            ops_map = getattr(cls, f"{op_attr_name}_op_nodes_map")
             for op in ops:
                 op_node = ops_map[op]
                 if op_node is not None:
                     made_op = _op_maker(op_class, op)
-                    setattr(cls, "visit_{node}".format(node=op_node), made_op)
+                    setattr(cls, f"visit_{op_node}", made_op)
         return cls
 
     return f
@@ -529,8 +528,8 @@ def _maybe_evaluate_binop(
 
         if res.has_invalid_return_type:
             raise TypeError(
-                "unsupported operand type(s) for {op}:"
-                " '{lhs}' and '{rhs}'".format(op=res.op, lhs=lhs.type, rhs=rhs.type)
+                f"unsupported operand type(s) for {res.op}:"
+                f" '{lhs.type}' and '{rhs.type}'"
             )
 
         if self.engine != "pytables":
@@ -677,7 +676,7 @@ def visit_Attribute(self, node, **kwargs):
                 if isinstance(value, ast.Name) and value.id == attr:
                     return resolved
 
-        raise ValueError("Invalid Attribute context {name}".format(name=ctx.__name__))
+        raise ValueError(f"Invalid Attribute context {ctx.__name__}")
 
     def visit_Call(self, node, side=None, **kwargs):
 
@@ -697,7 +696,7 @@ def visit_Call(self, node, side=None, **kwargs):
                     raise
 
         if res is None:
-            raise ValueError("Invalid function call {func}".format(func=node.func.id))
+            raise ValueError(f"Invalid function call {node.func.id}")
         if hasattr(res, "value"):
             res = res.value
 
@@ -707,8 +706,7 @@ def visit_Call(self, node, side=None, **kwargs):
 
             if node.keywords:
                 raise TypeError(
-                    'Function "{name}" does not support keyword '
-                    "arguments".format(name=res.name)
+                    f'Function "{res.name}" does not support keyword arguments'
                 )
 
             return res(*new_args, **kwargs)
@@ -719,10 +717,7 @@ def visit_Call(self, node, side=None, **kwargs):
 
             for key in node.keywords:
                 if not isinstance(key, ast.keyword):
-                    raise ValueError(
-                        "keyword error in function call "
-                        "'{func}'".format(func=node.func.id)
-                    )
+                    raise ValueError(f"keyword error in function call '{node.func.id}'")
 
                 if key.arg:
                     kwargs[key.arg] = self.visit(key.value).value

pandas/core/computation/expressions.py

@@ -109,7 +109,7 @@ def _evaluate_numexpr(op, op_str, a, b):
         b_value = getattr(b, "values", b)
 
         result = ne.evaluate(
-            "a_value {op} b_value".format(op=op_str),
+            f"a_value {op_str} b_value",
             local_dict={"a_value": a_value, "b_value": b_value},
             casting="safe",
         )

pandas/core/computation/ops.py

@@ -212,8 +212,8 @@ def __repr__(self) -> str:
         Print a generic n-ary operator and its operands using infix notation.
         """
         # recurse over the operands
-        parened = ("({0})".format(pprint_thing(opr)) for opr in self.operands)
-        return pprint_thing(" {0} ".format(self.op).join(parened))
+        parened = (f"({pprint_thing(opr)})" for opr in self.operands)
+        return pprint_thing(f" {self.op} ".join(parened))
 
     @property
     def return_type(self):
@@ -506,8 +506,8 @@ def __init__(self, lhs, rhs, **kwargs):
 
         if not isnumeric(lhs.return_type) or not isnumeric(rhs.return_type):
             raise TypeError(
-                "unsupported operand type(s) for {0}:"
-                " '{1}' and '{2}'".format(self.op, lhs.return_type, rhs.return_type)
+                f"unsupported operand type(s) for {self.op}:"
+                f" '{lhs.return_type}' and '{rhs.return_type}'"
             )
 
         # do not upcast float32s to float64 un-necessarily
@@ -554,7 +554,7 @@ def __call__(self, env):
         return self.func(operand)
 
     def __repr__(self) -> str:
-        return pprint_thing("{0}({1})".format(self.op, self.operand))
+        return pprint_thing(f"{self.op}({self.operand})")
 
     @property
     def return_type(self) -> np.dtype:
@@ -580,7 +580,7 @@ def __call__(self, env):
 
     def __repr__(self) -> str:
         operands = map(str, self.operands)
-        return pprint_thing("{0}({1})".format(self.op, ",".join(operands)))
+        return pprint_thing(f"{self.op}({','.join(operands)})")
 
 
 class FuncNode:
@@ -592,7 +592,7 @@ def __init__(self, name: str):
             and _NUMEXPR_VERSION < LooseVersion("2.6.9")
             and name in ("floor", "ceil")
         ):
-            raise ValueError('"{0}" is not a supported function'.format(name))
+            raise ValueError(f'"{name}" is not a supported function')
 
         self.name = name
         self.func = getattr(np, name)