Merge pull request #21 from petbox-dev/pipe

Add `pipe()` method

README.rst

@@ -86,7 +86,8 @@ and SQL-style "group by" and join operations.
 +----------------------------+-----------------------------------------------------------------------------------------------------------------------------+
 | Functional Methods         | `row_map <https://tafra.readthedocs.io/en/latest/api.html#tafra.base.Tafra.row_map>`_,                                      |
 |                            | `tuple_map <https://tafra.readthedocs.io/en/latest/api.html#tafra.base.Tafra.tuple_map>`_,                                  |
-|                            | `col_map <https://tafra.readthedocs.io/en/latest/api.html#tafra.base.Tafra.col_map>`_                                       |
+|                            | `col_map <https://tafra.readthedocs.io/en/latest/api.html#tafra.base.Tafra.col_map>`_,                                      |
+|                            | `pipe <https://tafra.readthedocs.io/en/latest/api.html#tafra.base.Tafra.pipe>`_                                             |
 +----------------------------+-----------------------------------------------------------------------------------------------------------------------------+
 | Dict-like Methods          | `keys <https://tafra.readthedocs.io/en/latest/api.html#tafra.base.Tafra.keys>`_,                                            |
 |                            | `values <https://tafra.readthedocs.io/en/latest/api.html#tafra.base.Tafra.values>`_,                                        |

docs/api.rst

@@ -70,6 +70,7 @@ Methods
     tuple_map
     col_map
     key_map
+    pipe
     select
     copy
     update
@@ -168,6 +169,8 @@ Methods
     .. automethod:: tuple_map
     .. automethod:: col_map
     .. automethod:: key_map
+    .. automethod:: pipe
+    .. automethod:: __rshift__
     .. automethod:: select
     .. automethod:: copy
     .. automethod:: update

docs/versions.rst

@@ -5,6 +5,20 @@ Version History
 .. automodule:: tafra
    :noindex:
 
+1.0.10
+------
+
+* Add ``pipe`` and overload ``>>`` operator for Tafra objects
+
+1.0.9
+-----
+
+* Add test files to build
+
+1.0.8
+-----
+
+* Check rows in constructor to ensure equal data length
 
 1.0.7
 -----

setup.py

@@ -17,14 +17,20 @@
 import sys
 import re
 
-from tafra import __version__
-
 try:
     from setuptools import setup
 except ImportError:
     from distutils.core import setup
 
 
+def find_version() -> str:
+    v = {}
+    with open('tafra/version.py', 'r') as f:
+        exec(f.read(), globals(), v)
+
+    return v['__version__']
+
+
 def get_long_description() -> str:
     # Fix display issues on PyPI caused by RST markup
     with open('README.rst', 'r') as f:
@@ -60,16 +66,19 @@ def replace(s: str) -> str:
 
     return readme + '\n\n' + version_history
 
+
+__version__ = find_version()
+
 if sys.argv[-1] == 'build':
-    print(f'\nBuilding version {__version__}...\n')
+    print(f'\nBuilding __version__ {__version__}...\n')
     os.system('rm -r dist\\')  # clean out dist/
     os.system('python setup.py sdist bdist_wheel')
     sys.exit()
 
 
 setup(
     name='tafra',
-    version=__version__,
+    __version__=__version__,
     description='Tafra: innards of a dataframe',
     long_description=get_long_description(),
     long_description_content_type="text/x-rst",

tafra/__init__.py

@@ -12,7 +12,8 @@
 -----
 Created on April 25, 2020
 """
-__version__ = '1.0.9'
+
+from .version import __version__
 
 from .base import Tafra, object_formatter
 from .group import GroupBy, Transform, IterateBy, InnerJoin, LeftJoin

tafra/base.py

@@ -29,17 +29,19 @@
 
 from typing import (Any, Callable, Dict, Mapping, List, Tuple, Optional, Union as _Union, Sequence,
                     Sized, Iterable, Iterator, Type, KeysView, ValuesView, ItemsView,
-                    IO)
+                    IO, Concatenate, ParamSpec)
 from typing import cast
 from io import TextIOWrapper
 
 from .formatter import ObjectFormatter
 from .csvreader import CSVReader
 
 
-object_formatter = ObjectFormatter()
+P = ParamSpec('P')
+
 
 # default object formats
+object_formatter = ObjectFormatter()
 object_formatter['Decimal'] = lambda x: x.astype(float)
 
 
@@ -333,6 +335,14 @@ def __getitem__(
     def __setitem__(self, item: str, value: _Union[np.ndarray, Sequence[Any], Any]) -> None:
         self._ensure_valid(item, value, set_item=True)
 
+    def __repr__(self) -> str:
+        if not hasattr(self, '_rows'):
+            return f'Tafra(data={self._data}, dtypes={self._dtypes}, rows=n/a)'
+        return f'Tafra(data={self._data}, dtypes={self._dtypes}, rows={self._rows})'
+
+    def __str__(self) -> str:
+        return self.__repr__()
+
     def __len__(self) -> int:
         assert self._data is not None, \
             'Interal error: Cannot construct a Tafra with no data.'
@@ -341,6 +351,9 @@ def __len__(self) -> int:
     def __iter__(self) -> Iterator['Tafra']:
         return (self._iindex(i) for i in range(self._rows))
 
+    def __rshift__(self, other: Callable[['Tafra'], 'Tafra']) -> 'Tafra':
+        return self.pipe(other)
+
     def iterrows(self) -> Iterator['Tafra']:
         """
         Yield rows as :class:`Tafra`. Use :meth:`itertuples` for better performance.
@@ -386,12 +399,6 @@ def itercols(self) -> Iterator[Tuple[str, np.ndarray]]:
         """
         return map(tuple, self.data.items())  # type: ignore
 
-    def __str__(self) -> str:
-        return self.__repr__()
-
-    def __repr__(self) -> str:
-        return f'Tafra(data={self._data}, dtypes={self._dtypes}, rows={self._rows})'
-
     def _update_rows(self) -> None:
         """
         Updates :attr:`_rows`. User should call this if they have directly assigned to
@@ -756,7 +763,7 @@ def _ensure_valid(self, column: str, value: _Union[np.ndarray, Sequence[Any], An
                 value = sq_value
 
         assert value.ndim >= 1, \
-            'Interal error: `Tafra` only supports assigning ndim >= 1.'
+            'Interal error: `Tafra` only supports assigning ndim == 1.'
 
         if check_rows and len(value) != rows:
             raise ValueError(
@@ -1270,8 +1277,7 @@ def tuple_map(self, fn: Callable[..., Any], *args: Any, **kwargs: Any) -> Iterat
         name = kwargs.pop('name', 'Tafra')
         return (fn(tf, *args, **kwargs) for tf in self.itertuples(name))
 
-    def col_map(self, fn: Callable[..., Any], keys: bool = True,
-                *args: Any, **kwargs: Any) -> Iterator[Any]:
+    def col_map(self, fn: Callable[..., Any], *args: Any, **kwargs: Any) -> Iterator[Any]:
         """
         Map a function over columns. To apply to specific columns, use :meth:`select`
         first. The function must operate on :class:`Tuple[str, np.ndarray]`.
@@ -1281,9 +1287,6 @@ def col_map(self, fn: Callable[..., Any], keys: bool = True,
             fn: Callable[..., Any]
                 The function to map.
 
-            keys: bool = True
-                Return a tuple
-
             *args: Any
                 Additional positional arguments to ``fn``.
 
@@ -1298,7 +1301,7 @@ def col_map(self, fn: Callable[..., Any], keys: bool = True,
 
         return (fn(value, *args, **kwargs) for column, value in self.itercols())
 
-    def key_map(self, fn: Callable[..., Any], keys: bool = True,
+    def key_map(self, fn: Callable[..., Any],
                 *args: Any, **kwargs: Any) -> Iterator[Tuple[str, Any]]:
         """
         Map a function over columns like :meth:col_map, but return :class:`Tuple` of the
@@ -1310,9 +1313,6 @@ def key_map(self, fn: Callable[..., Any], keys: bool = True,
             fn: Callable[..., Any]
                 The function to map.
 
-            keys: bool = True
-                Return a tuple
-
             *args: Any
                 Additional positional arguments to ``fn``.
 
@@ -1324,23 +1324,31 @@ def key_map(self, fn: Callable[..., Any], keys: bool = True,
             iter_tf: Iterator[Any]
                 An iterator to map the function.
         """
-        return ((column, fn(value, *args, **kwargs))
-                for column, value in self.itercols())
+        return ((column, fn(value, *args, **kwargs)) for column, value in self.itercols())
 
-    def head(self, n: int = 5) -> 'Tafra':
+    def pipe(self, fn: Callable[Concatenate['Tafra', P], 'Tafra'],
+             *args: Any, **kwargs: Any) -> 'Tafra':
         """
-        Display the head of the :class:`Tafra`.
+        Apply a function to the :class:`Tafra` and return the resulting :class:`Tafra`. Primarily
+        used to build a tranformer pipeline.
 
         Parameters
         ----------
-            n: int = 5
-                The number of rows to display.
+            fn: Callable[[], 'Tafra']
+                The function to apply.
+
+            *args: Any
+                Additional positional arguments to ``fn``.
+
+            **kwargs: Any
+                Additional keyword arguments to ``fn``.
 
         Returns
         -------
-            None: None
+            tafra: Tafra
+                A new :class:`Tafra` result of the function.
         """
-        return self._slice(slice(n))
+        return fn(self, *args, **kwargs)
 
     def select(self, columns: Iterable[str]) -> 'Tafra':
         """
@@ -1368,6 +1376,21 @@ def select(self, columns: Iterable[str]) -> 'Tafra':
             validate=False
         )
 
+    def head(self, n: int = 5) -> 'Tafra':
+        """
+        Display the head of the :class:`Tafra`.
+
+        Parameters
+        ----------
+            n: int = 5
+                The number of rows to display.
+
+        Returns
+        -------
+            None: None
+        """
+        return self._slice(slice(n))
+
     def keys(self) -> KeysView[str]:
         """
         Return the keys of :attr:`data`, i.e. like :meth:`dict.keys()`.

tafra/version.py

@@ -0,0 +1 @@
+__version__ = '1.0.10'

test/test_tafra.py

@@ -542,13 +542,13 @@ def test_update_dtypes() -> None:
     t.update_dtypes_inplace({'x': float})
     check_tafra(t)
     assert t['x'].dtype == 'float'
-    assert isinstance(t['x'][0], np.float)
+    assert isinstance(t['x'][0], np.float64)
 
     t = build_tafra()
     _ = t.update_dtypes({'x': float})
     check_tafra(_)
     assert _['x'].dtype == 'float'
-    assert isinstance(_['x'][0], np.float)
+    assert isinstance(_['x'][0], np.float64)
 
 def test_rename() -> None:
     t = build_tafra()
@@ -704,11 +704,34 @@ def test_invalid_agg() -> None:
 
 def test_map() -> None:
     t = build_tafra()
-    _ = list(t.row_map(np.repeat, 6))
-    _ = list(t.tuple_map(np.repeat, 6))
-    _ = list(t.col_map(np.repeat, repeats=6))
+
+    def repeat(tf: Tafra, repeats: int) -> Tafra:
+        return [tf for _ in range(repeats)]
+
+    _ = list(t.row_map(repeat, 6))
+    _ = list(t.tuple_map(repeat, 6))
+    _ = list(t.col_map(repeat, repeats=6))
     _ = Tafra(t.key_map(np.repeat, repeats=6))
 
+def test_pipe() -> None:
+    def fn1(t: Tafra) -> Tafra:
+        return t[t['y'] == 'one']
+    def fn2(t: Tafra) -> Tafra:
+        return t[t['z'] == 0]
+
+    t = build_tafra()
+    check_tafra(t.pipe(fn1))
+    check_tafra(t >> fn1)
+    check_tafra(t.pipe(fn1).pipe(fn2))
+    check_tafra(t >> fn1 >> fn2)
+
+    def fn3(t: Tafra, i: int) -> Tafra:
+        return t[t['x'] == i]
+
+    check_tafra(t.pipe(fn3, 1))
+    check_tafra(t.pipe(fn3, i=1))
+    check_tafra(t >> (lambda t: fn3(t, i=1)))
+
 def test_union() -> None:
     t = build_tafra()
     t2 = build_tafra()
@@ -1178,7 +1201,7 @@ def write_reread(t: Tafra) -> None:
     check_tafra(t)
 
     # force dtypes on missing columns
-    t = Tafra.read_csv('test/ex6.csv', missing=None, dtypes={'dp_prime': np.float, 'dp_prime_te': np.float32})
+    t = Tafra.read_csv('test/ex6.csv', missing=None, dtypes={'dp_prime': np.float64, 'dp_prime_te': np.float32})
     assert t.dtypes['dp'] == 'float64'
     assert t.dtypes['dp_prime'] == 'float64'
     assert t.dtypes['dp_prime_te'] == 'float32'