Pipes are a new feature in Pandas 0.16.2.

Example:

import pandas as pdfrom sklearn.datasets import load_irisx = load_iris()x = pd.DataFrame(x.data, columns=x.feature_names)def remove_units(df):    df.columns = pd.Index(map(lambda x: x.replace(" (cm)", ""), df.columns))    return dfdef length_times_width(df):    df['sepal length*width'] = df['sepal length'] * df['sepal width']    df['petal length*width'] = df['petal length'] * df['petal width']x.pipe(remove_units).pipe(length_times_width)x

NB: The Pandas version retains Python's reference semantics. That's why length_times_width doesn't need a return value; it modifies x in place.

One possible way of doing this is by using a module called macropy. Macropy allows you to apply transformations to the code that you have written. Thus a | b can be transformed to b(a). This has a number of advantages and disadvantages.

In comparison to the solution mentioned by Sylvain Leroux, The main advantage is that you do not need to create infix objects for the functions you are interested in using -- just mark the areas of code that you intend to use the transformation. Secondly, since the transformation is applied at compile time, rather than runtime, the transformed code suffers no overhead during runtime -- all the work is done when the byte code is first produced from the source code.

The main disadvantages are that macropy requires a certain way to be activated for it to work (mentioned later). In contrast to a faster runtime, the parsing of the source code is more computationally complex and so the program will take longer to start. Finally, it adds a syntactic style that means programmers who are not familiar with macropy may find your code harder to understand.

Example Code:

run.py

import macropy.activate # Activates macropy, modules using macropy cannot be imported before this statement# in the program.import target# import the module using macropy

target.py

from fpipe import macros, fpipefrom macropy.quick_lambda import macros, f# The `from module import macros, ...` must be used for macropy to know which # macros it should apply to your code.# Here two macros have been imported `fpipe`, which does what you want# and `f` which provides a quicker way to write lambdas.from math import sqrt# Using the fpipe macro in a single expression.# The code between the square braces is interpreted as - str(sqrt(12))print fpipe[12 | sqrt | str] # prints 3.46410161514# using a decorator# All code within the function is examined for `x | y` constructs.x = 1 # global variable@fpipedef sum_range_then_square():    "expected value (1 + 2 + 3)**2 -> 36"    y = 4 # local variable    return range(x, y) | sum | f[_**2]    # `f[_**2]` is macropy syntax for -- `lambda x: x**2`, which would also work hereprint sum_range_then_square() # prints 36# using a with block.# same as a decorator, but for limited blocks.with fpipe:    print range(4) | sum # prints 6    print 'a b c' | f[_.split()] # prints ['a', 'b', 'c']

And finally the module that does the hard work. I've called it fpipe for functional pipe as its emulating shell syntax for passing output from one process to another.

fpipe.py

from macropy.core.macros import *from macropy.core.quotes import macros, q, astmacros = Macros()@macros.decorator@macros.block@macros.exprdef fpipe(tree, **kw):    @Walker    def pipe_search(tree, stop, **kw):        """Search code for bitwise or operators and transform `a | b` to `b(a)`."""        if isinstance(tree, BinOp) and isinstance(tree.op, BitOr):            operand = tree.left            function = tree.right            newtree = q[ast[function](ast[operand])]            return newtree    return pipe_search.recurse(tree)

PyToolz [doc] allows arbitrarily composable pipes, just they aren't defined with that pipe-operator syntax.

Follow the above link for the quickstart. And here's a video tutorial: http://pyvideo.org/video/2858/functional-programming-in-python-with-pytoolz

In [1]: from toolz import pipeIn [2]: from math import sqrtIn [3]: pipe(12, sqrt, str)Out[3]: '3.4641016151377544'