knife.lazy.mathknife — Lazier evaluated mathing knife¶

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

Lazier evaluated mathing knife. Provides numeric and statistical operations for incoming things.

>>> from knife.lazy import mathknife

__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,)']

average()¶

Discover average value among incoming things.

Returns:	a number
Return type:	knife object

>>> from knife import __
>>> __(10, 40, 45).average().get()
31.666666666666668

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

count()¶

Discover how common each incoming thing is and the overall count of each incoming thing.

Returns:	Collects namedtuple Count(least=int, most=int, overall=[(thing1, int), (thing2, int), ...])
Return type:	knife object

>>> common = __(11, 3, 5, 11, 7, 3, 5, 11).count().get()
>>> # least common thing
>>> common.least
7
>>> # most common thing
>>> common.most
11
>>> # total count for every thing
>>> common.overall
[(11, 3), (3, 2), (5, 2), (7, 1)]

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).

max()¶

Discover the maximum value among incoming things using worker as the key function.

Return type:	knife object

>>> # default behavior
>>> __(1, 2, 4).max().get()
4
>>> stooges = (
...    {'name': 'moe', 'age': 40},
...    {'name': 'larry', 'age': 50},
...    {'name': 'curly', 'age': 60},
... )
>>> # using worker as key function
>>> __(*stooges).worker(lambda x: x['age']).max().get()
{'age': 60, 'name': 'curly'}

See also

max

function in Python standard library

max

function in Underscore.js

max

function in Underscore.lua

max

function in Underscore.perl

max

function in Underscore.php

median()¶

Discover the median value among incoming things.

Returns:	a number
Return type:	knife object

>>> __(4, 5, 7, 2, 1).median().get()
4
>>> __(4, 5, 7, 2, 1, 8).median().get()
4.5

min()¶

Discover the minimum value among incoming things using worker as the key function.

Return type:	knife object

>>> test = __(10, 5, 100, 2, 1000)
>>> test.min().get()
2
>>> test.original().worker(lambda x: x % 100 == 0).min().get()
10

See also

min

function in Python standard library

min

function in Underscore.js

min

function in Underscore.lua

min

function in Underscore.perl

min

function in Underscore.php

minmax()¶

Discover the minimum and maximum values among incoming things.

Returns:	namedtuple MinMAx(min=value, max=value).
Return type:	knife object

>>> minmax = __(1, 2, 4).minmax().get()
>>> minmax.min
1
>>> minmax.max
4

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]

range()¶

Discover the length of the smallest interval that can contain the value of every incoming thing.

Returns:	a number
Return type:	knife object

>>> __(3, 5, 7, 3, 11).range().get()
8

snapshot()¶

Take a baseline snapshot of current incoming things.

Return type:	knife object

sum(start=0, precision=False)¶

Discover the total value of adding start and incoming things together.

Parameters:	start (int or float) – starting number precision (bool) – add floats with extended precision
Return type:	knife object

>>> # default behavior
>>> __(1, 2, 3).sum().get()
6
>>> # with a starting mumber
>>> __(1, 2, 3).sum(start=1).get()
7
>>> # add floating points with extended precision
>>> __(.1, .1, .1, .1, .1, .1, .1, .1).sum(precision=True).get()
0.8

See also

sum

function in Python standard library

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)