knife documentation

knife.active.sliceknife — Actively evaluated slicing knife

«  knife.active.repeatknife — Actively evaluated repeating knife   ::   Contents

knife.active.sliceknife — Actively evaluated slicing knife

class knife.active.sliceknife(*things, **kw)

Actively evaluated slicing knife. Provides slicing operations for incoming things.

>>> from knife.active import sliceknife
__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,)']
at(n, default=None)

Slice off incoming thing found at index n.

Parameters:
  • n (int) – index of some incoming thing
  • default – default returned if nothing is found at n
Return type:

knife object

>>> from knife import __
>>> # default behavior
>>> __(5, 4, 3, 2, 1).at(2).get()
3
>>> # return default value if nothing found at index
>>> __(5, 4, 3, 2, 1).at(10, 11).get()
11

See also

“nth”
Itertools Recipes
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:
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,)']
choice()

Randomly slice off one incoming thing.

Return type:knife object
>>> __(1, 2, 3, 4, 5, 6).choice().get() 
3

See also

random.choice
function in Python standard library
clear()

Clear everything.

Return type:knife object
dice(n, fill=None)

Slice one iterable incoming thing into n iterable incoming things.

Parameters:
  • n (int) – number of incoming things per slice
  • fill – value to pad out incomplete iterables
Return type:

knife object

>>> __('moe', 'larry', 'curly', 30, 40, 50, True).dice(2, 'x').get()
[('moe', 'larry'), ('curly', 30), (40, 50), (True, 'x')]

See also

“grouper”
Itertools Recipes
first(n=0)

Slice off n things from the starting end of incoming things or just the first incoming thing.

Parameters:n (int) – number of incoming things
Return type:knife object
>>> # default behavior
>>> __(5, 4, 3, 2, 1).first().get()
5
>>> # first things from index 0 to 2
>>> __(5, 4, 3, 2, 1).first(2).get()
[5, 4]

See also

first
function in Underscore.js
first
function in Underscore.lua
first
function in Underscore.perl
first
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).

initial()

Slice off every incoming thing except the last incoming thing.

Return type:knife object
>>> __(5, 4, 3, 2, 1).initial().get()
[5, 4, 3, 2]

See also

initial
function in Underscore.js
initial
function in Underscore.lua
initial
function in Underscore.perl
initial
function in Underscore.php
last(n=0)

Slice off n things from the tail end of incoming things or just the last incoming thing.

Parameters:n (int) – number of incoming things
Return type:knife object
>>> # default behavior
>>> __(5, 4, 3, 2, 1).last().get()
1
>>> # fetch last two things
>>> __(5, 4, 3, 2, 1).last(2).get()
[2, 1]

See also

last
function in Underscore.js
last
function in Underscore.lua
last
function in Underscore.perl
last
function in Underscore.php
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:
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]
rest()

Slice off every incoming thing except the first incoming thing.

Return type:knife object
>>> __(5, 4, 3, 2, 1).rest().get()
[4, 3, 2, 1]

See also

rest
function in Underscore.js
rest
function in Underscore.lua
rest
function in Underscore.perl
rest
function in Underscore.php
sample(n)

Randomly slice off n incoming things.

Parameters:n (int) – sample size
Return type:knife object
>>> __(1, 2, 3, 4, 5, 6).sample(3).get() 
[2, 4, 5]

See also

random.sample
function in Python standard library
slice(start, stop=False, step=False)

Take slice out of incoming things.

Parameters:
  • start (int) – starting index of slice
  • stop (int) – stopping index of slice
  • step (int) – size of step in slice
Return type:

knife object

>>> # slice from index 0 to 3
>>> __(5, 4, 3, 2, 1).slice(2).get()
[5, 4]
>>> # slice from index 2 to 4
>>> __(5, 4, 3, 2, 1).slice(2, 4).get()
[3, 2]
>>> # slice from index 2 to 4 with 2 steps
>>> __(5, 4, 3, 2, 1).slice(2, 4, 2).get()
3

See also

itertools.islice
function in Python standard library
slice
function in Underscore.lua
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:
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)

«  knife.active.repeatknife — Actively evaluated repeating knife   ::   Contents