`knife.lazy.reduceknife` — Lazier evaluated reducing knife¶

class knife.lazy.reduceknife(*things, **kw)¶

Lazier evaluated reducing knife. Provides reducing operations for incoming things.

>>> from knife.lazy import reduceknife

__init__(*things, snapshots=5)¶

Parameters:	things – incoming things snapshots (integer) – snapshots to keep (default: `5`)

__len__()¶: Number of incoming things.

__iter__()¶: Iterate over outgoing things.

append(*things)¶

Insert things after other incoming things.

Parameters:	things – incoming things
Return type:	`knife` object

>>> from knife import __
>>> __(3, 4, 5).append(1, 2, 3, 4, 5, 6).peek()
[3, 4, 5, 1, 2, 3, 4, 5, 6]

apply(worker, *args, **kw)¶

Assign callable used to work on incoming things plus any positional arguments and keyword arguments it will use.

Note

Global positional arguments and keyword arguments assigned with params are reset whenever apply is called.

Parameters:	worker – a `callable`
Return type:	`knife` object

ascii(errors='strict')¶

encode outgoing things as bytes with the 'latin-1' codec.

Parameters:	errors (str) – error handling for encoding
Return type:	`knife` object

>>> from stuf.six import u, b
>>> test = __([1], True, r't', b('i'), u('g'), None, (1,))
>>> test.ascii().oneach().peek()
['[1]', 'True', 't', 'i', 'g', 'None', '(1,)']

back()¶

Switch back to knife object that piped its incoming things through this knife object.

Return type:	`knife` object

baseline()¶

Restore incoming things back to the baseline snapshot.

Return type:	`knife` object

>>> from knife import __
>>> undone = __(1, 2, 3).prepend(1, 2, 3, 4, 5, 6)
>>> undone.peek()
[1, 2, 3, 4, 5, 6, 1, 2, 3]
>>> undone.snapshot().append(1).append(2).peek()
[1, 2, 3, 4, 5, 6, 1, 2, 3, 1, 2]
>>> undone.baseline().peek()
[1, 2, 3, 4, 5, 6, 1, 2, 3]

bytes(encoding='utf_8', errors='strict')¶

encode outgoing things as bytes.

Parameters:	encoding (str) – character encoding errors (str) – error handling for encoding
Return type:	`knife` object

>>> test = __([1], True, r't', b('i'), u('g'), None, (1,))
>>> test.bytes().oneach().peek()
['[1]', 'True', 't', 'i', 'g', 'None', '(1,)']

clear()¶

Clear everything.

Return type:	`knife` object

flatten()¶

Reduce nested incoming things to flattened incoming things.

Return type:	`knife` object

>>> from knife import __
>>> __([[1, [2], [3, [[4]]]], 'here']).flatten().get()
[1, 2, 3, 4, 'here']

See also

flatten: function in Underscore.js
flatten: function in Underscore.lua
flatten: function in Underscore.perl
flatten: function in Underscore.php

get()¶: Return outgoing things wrapped with wrap.

Note

With only one outgoing thing, only that one outgoing thing is returned. With multiple outgoing things, they are returned wrapped with the wrapper assigned with wrap (default wrapper is list).

merge()¶

Reduce multiple iterable incoming things into one iterable incoming thing.

Return type:	`knife` object

>>> __(['moe', 'larry'], [30, 40], [True, False]).merge().get()
['moe', 'larry', 30, 40, True, False]

See also

itertools.chain.from_iterable: function in Python standard library

oneach()¶

Toggle whether each outgoing thing should be individually wrapped with the wrapper assigned with wrap (default wrapper is list ) or whether all outgoing things should be wrapped all at once.

Note

knife object default behavior is to wrap all outgoing things all at once. knife objects reset back to this behavior after get or peek is called.

Return type:	`knife` object

original()¶

Restore incoming things back to the original snapshot.

Note

THe original snapshot of incoming things is taken following the first knife method call but before the second knife method call (if there is a second method call)

Return type:	`knife` object

>>> undone = __(1, 2, 3).prepend(1, 2, 3, 4, 5, 6)
>>> undone.peek()
[1, 2, 3, 4, 5, 6, 1, 2, 3]
>>> undone.original().peek()
[1, 2, 3]

params(*args, **kw)¶

Assign positional arguments and keyword arguments to be used globally.

Return type:	`knife` object

pattern(pattern, type='parse', flags=0)¶

Compile search pattern for use as worker.

Note

Global positional arguments and keyword arguments assigned with params are reset whenever a new pattern is compiled.

Parameters:	pattern (str) – search pattern type (str) – engine to compile pattern with. Valid options are ‘parse’, ‘re’, or ‘glob’ flags (int) – regular expression flags
Return type:	`knife` object

>>> # using parse expression
>>> test = __('first test', 'second test', 'third test')
>>> test.pattern('first {}').filter().get()
'first test'
>>> # using glob pattern
>>> test.original().pattern('second*', type='glob').filter().get()
'second test'
>>> # using regular expression
>>> test.original().pattern('third .', type='regex').filter().get()
'third test'

peek()¶: Preview current incoming things wrapped with wrap.

Note

With only one outgoing thing, only that one thing is returned. With multiple outgoing things, everything is returned wrapped with the wrapper assigned with wrap (default wrapper is list).

pipe(knife)¶

Pipe incoming things from some other knife object through this knife object.

Parameters:	knife – another `knife` object
Return type:	`knife` object

prepend(*things)¶

Insert things before other incoming things.

Parameters:	things – incoming things
Return type:	`knife` object

>>> __(3, 4, 5).prepend(1, 2, 3, 4, 5, 6).peek()
[1, 2, 3, 4, 5, 6, 3, 4, 5]

reduce(initial=None, reverse=False)¶

Reduce iterable incoming things down to one incoming thing using worker.

Parameters:	initial – starting value reverse (bool) – reduce from the right side of incoming things
Return type:	`knife` object

>>> # reduce from left side
>>> __(1, 2, 3).worker(lambda x, y: x + y).reduce().get()
6
>>> # reduce from left side with initial value
>>> __(1, 2, 3).worker(lambda x, y: x + y).reduce(initial=1).get()
7
>>> # reduce from right side
>>> test = __([0, 1], [2, 3], [4, 5]).worker(lambda x, y: x + y)
>>> test.reduce(reverse=True).get()
[4, 5, 2, 3, 0, 1]
>>> # reduce from right side with initial value
>>> test.original().worker(
... lambda x, y: x + y
... ).reduce([0, 0], True).get()
[4, 5, 2, 3, 0, 1, 0, 0]

See also

functools.reduce: function in Python standard library
reduce: function in Underscore.js
reduceRight: function in Underscore.js
reduce: function in Underscore.lua
reduce: function in Underscore.perl
reduceRight: function in Underscore.perl
reduce: function in Underscore.php
reduceRight: function in Underscore.php

snapshot()¶

Take a baseline snapshot of current incoming things.

Return type:	`knife` object

undo(snapshot=0)¶

Revert incoming things to a previous snapshot.

Note

A snapshot of current incoming things is taken when a knife method is called but before the main body of the method executes.

Parameters:	snapshot (int) – number of steps ago `1`, `2`, `3`, etc.
Return type:	`knife` object

>>> undone = __(1, 2, 3).prepend(1, 2, 3, 4, 5, 6)
>>> undone.peek()
[1, 2, 3, 4, 5, 6, 1, 2, 3]
>>> # undo back one step
>>> undone.append(1).undo().peek()
[1, 2, 3, 4, 5, 6, 1, 2, 3]
>>> # undo back one step
>>> undone.append(1).append(2).undo().peek()
[1, 2, 3, 4, 5, 6, 1, 2, 3, 1]
>>> # undo back 2 steps
>>> undone.append(1).append(2).undo(2).peek()
[1, 2, 3, 4, 5, 6, 1, 2, 3, 1]

unicode(encoding='utf_8', errors='strict')¶

unicode (str under Python 3) decode outgoing things.

Parameters:	encoding (str) – Unicode encoding errors (str) – error handling for decoding
Return type:	`knife` object

>>> test = __([1], True, r't', b('i'), u('g'), None, (1,))
>>> test.unicode().oneach().peek()
[u'[1]', u'True', u't', u'i', u'g', u'None', u'(1,)']

worker(worker)¶

Assign callable used to work on incoming things.

Note

Global positional arguments and keyword arguments assigned with params are reset whenever a new worker is assigned.

Parameters:	worker – a `callable`
Return type:	`knife` object

wrap(wrapper)¶

Assign object, type, or class used to wrap outgoing things.

Note

A knife object resets back to its default wrapper (list) after get or peek is called.

Parameters:	wrapper – an object, `type`, or `class`
Return type:	`knife` object

>>> __(1, 2, 3, 4, 5, 6).wrap(tuple).peek()
(1, 2, 3, 4, 5, 6)

zip()¶

Convert multiple iterable incoming things to a series of tuples composed of things found at the same index position within the original iterables.

Return type:	`knife` object

>>> test = __(['moe', 'larry'], [30, 40], [True, False])
>>> test.zip().get()
[('moe', 30, True), ('larry', 40, False)]

See also

itertools.izip: function in Python standard library (replaces zip in Python 3)
zip: function in Underscore.js
zip: function in Underscore.perl
zip: function in Underscore.php

knife documentation