PERF faster head, tail and size groupby methods

pandas/compat/__init__.py

@@ -245,6 +245,7 @@ def wrapper(cls):
 
 
 class _OrderedDict(dict):
+
     """Dictionary that remembers insertion order"""
     # An inherited dict maps keys to values.
     # The inherited dict provides __getitem__, __len__, __contains__, and get.
@@ -505,6 +506,7 @@ def viewitems(self):
 
 
 class _Counter(dict):
+
     """Dict subclass for counting hashable objects.  Sometimes called a bag
     or multiset.  Elements are stored as dictionary keys and their counts
     are stored as dictionary values.

pandas/computation/engines.py

@@ -10,6 +10,7 @@
 
 
 class AbstractEngine(object):
+
     """Object serving as a base class for all engines."""
 
     __metaclass__ = abc.ABCMeta
@@ -73,6 +74,7 @@ def _evaluate(self):
 
 
 class NumExprEngine(AbstractEngine):
+
     """NumExpr engine class"""
     has_neg_frac = True
 
@@ -105,6 +107,7 @@ def _evaluate(self):
 
 
 class PythonEngine(AbstractEngine):
+
     """Evaluate an expression in Python space.
 
     Mostly for testing purposes.

pandas/computation/expr.py

@@ -70,6 +70,7 @@ def _raw_hex_id(obj, pad_size=2):
 
 
 class Scope(StringMixin):
+
     """Object to hold scope, with a few bells to deal with some custom syntax
     added by pandas.
 
@@ -324,6 +325,7 @@ def _node_not_implemented(node_name, cls):
     """Return a function that raises a NotImplementedError with a passed node
     name.
     """
+
     def f(self, *args, **kwargs):
         raise NotImplementedError("{0!r} nodes are not "
                                   "implemented".format(node_name))
@@ -356,6 +358,7 @@ def _op_maker(op_class, op_symbol):
     -------
     f : callable
     """
+
     def f(self, node, *args, **kwargs):
         """Return a partial function with an Op subclass with an operator
         already passed.
@@ -389,6 +392,7 @@ def f(cls):
 @disallow(_unsupported_nodes)
 @add_ops(_op_classes)
 class BaseExprVisitor(ast.NodeVisitor):
+
     """Custom ast walker. Parsers of other engines should subclass this class
     if necessary.
 
@@ -710,19 +714,22 @@ def visitor(x, y):
           (_boolop_nodes | frozenset(['BoolOp', 'Attribute', 'In', 'NotIn',
                                       'Tuple'])))
 class PandasExprVisitor(BaseExprVisitor):
+
     def __init__(self, env, engine, parser,
                  preparser=lambda x: _replace_locals(_replace_booleans(x))):
         super(PandasExprVisitor, self).__init__(env, engine, parser, preparser)
 
 
 @disallow(_unsupported_nodes | _python_not_supported | frozenset(['Not']))
 class PythonExprVisitor(BaseExprVisitor):
+
     def __init__(self, env, engine, parser, preparser=lambda x: x):
         super(PythonExprVisitor, self).__init__(env, engine, parser,
                                                 preparser=preparser)
 
 
 class Expr(StringMixin):
+
     """Object encapsulating an expression.
 
     Parameters
@@ -734,6 +741,7 @@ class Expr(StringMixin):
     truediv : bool, optional, default True
     level : int, optional, default 2
     """
+
     def __init__(self, expr, engine='numexpr', parser='pandas', env=None,
                  truediv=True, level=2):
         self.expr = expr

pandas/computation/ops.py

@@ -27,7 +27,9 @@
 
 
 class UndefinedVariableError(NameError):
+
     """NameError subclass for local variables."""
+
     def __init__(self, *args):
         msg = 'name {0!r} is not defined'
         subbed = _TAG_RE.sub('', args[0])
@@ -51,6 +53,7 @@ def _possibly_update_key(d, value, old_key, new_key=None):
 
 
 class Term(StringMixin):
+
     def __new__(cls, name, env, side=None, encoding=None):
         klass = Constant if not isinstance(name, string_types) else cls
         supr_new = super(Term, klass).__new__
@@ -195,6 +198,7 @@ def ndim(self):
 
 
 class Constant(Term):
+
     def __init__(self, value, env, side=None, encoding=None):
         super(Constant, self).__init__(value, env, side=side,
                                        encoding=encoding)
@@ -211,8 +215,10 @@ def name(self):
 
 
 class Op(StringMixin):
+
     """Hold an operator of unknown arity
     """
+
     def __init__(self, op, operands, *args, **kwargs):
         self.op = _bool_op_map.get(op, op)
         self.operands = operands
@@ -328,6 +334,7 @@ def is_term(obj):
 
 
 class BinOp(Op):
+
     """Hold a binary operator and its operands
 
     Parameters
@@ -336,6 +343,7 @@ class BinOp(Op):
     left : Term or Op
     right : Term or Op
     """
+
     def __init__(self, op, lhs, rhs, **kwargs):
         super(BinOp, self).__init__(op, (lhs, rhs))
         self.lhs = lhs
@@ -452,6 +460,7 @@ def _disallow_scalar_only_bool_ops(self):
 
 
 class Div(BinOp):
+
     """Div operator to special case casting.
 
     Parameters
@@ -462,6 +471,7 @@ class Div(BinOp):
         Whether or not to use true division. With Python 3 this happens
         regardless of the value of ``truediv``.
     """
+
     def __init__(self, lhs, rhs, truediv=True, *args, **kwargs):
         super(Div, self).__init__('/', lhs, rhs, *args, **kwargs)
 
@@ -475,6 +485,7 @@ def __init__(self, lhs, rhs, truediv=True, *args, **kwargs):
 
 
 class UnaryOp(Op):
+
     """Hold a unary operator and its operands
 
     Parameters
@@ -489,6 +500,7 @@ class UnaryOp(Op):
     ValueError
         * If no function associated with the passed operator token is found.
     """
+
     def __init__(self, op, operand):
         super(UnaryOp, self).__init__(op, (operand,))
         self.operand = operand

pandas/computation/pytables.py

@@ -30,6 +30,7 @@ def __init__(self, gbls=None, lcls=None, queryables=None, level=1):
 
 
 class Term(ops.Term):
+
     def __new__(cls, name, env, side=None, encoding=None):
         klass = Constant if not isinstance(name, string_types) else cls
         supr_new = StringMixin.__new__
@@ -57,6 +58,7 @@ def value(self):
 
 
 class Constant(Term):
+
     def __init__(self, value, env, side=None, encoding=None):
         super(Constant, self).__init__(value, env, side=side,
                                        encoding=encoding)
@@ -292,9 +294,9 @@ def __unicode__(self):
 
     def invert(self):
         """ invert the condition """
-        #if self.condition is not None:
+        # if self.condition is not None:
         #    self.condition = "~(%s)" % self.condition
-        #return self
+        # return self
         raise NotImplementedError("cannot use an invert condition when "
                                   "passing to numexpr")