unipy.utils.generator module¶

Docstring for generator.

Versatile Generators¶

Productivity
ReusableGenerator	Reusable Generator.
re_generator	Functional API for `ReusableGenerator`.

Lazy Evaluation
split_generator	Split data by given size.

Range Generator
num_fromto_generator	Range number string pairs by given term.
dt_fromto_generator	Range date format string pairs by given term.
tm_fromto_generator	Range datetime format string pairs by given term.
timestamp_generator	Range timestamp string pairs by given term.

class unipy.utils.generator.ReusableGenerator(generator)[source]¶

Bases: object

Temporary Interface to re-use generator for convenience.

Once assigned, It can be infinitely consumed **as long as an input generator remains un-exhausted.

_source¶

A source generator.

Type: generator

See also

generator itertools.tee

Examples

>>> from unipy.utils.generator import ReusableGenerator
>>> gen = (i for i in range(10))
>>> gen
<generator object <genexpr> at 0x11120ebf8>
>>> regen = ReusableGenerator(gen)
>>> regen
<unipy.utils.generator.ReusableGenerator object at 0x1061a97f0>
>>> list(regen)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> list(regen)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> list(gen)  # If the source is used, copied one will be exhausted too.
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> list(gen)
[]
>>> list(regen)
[]

unipy.utils.generator.re_generator(generator)[source]¶

A functional API for unipy.ReusableGenerator.

Once assigned, It can be infinitely consumed **as long as an output generator is called at least one time.

Parameters: generator (generator) – An generator to copy. This original generator should not be used anywhere else, until the copied one consumed at least once.
Returns: A generator to be used infinitely.
Return type: generator

See also

generator itertools.tee

Examples

>>> from unipy.utils.generator import re_generator
>>> gen = (i for i in range(10))
>>> gen
<generator object <genexpr> at 0x11120ebf8>
>>> regen = copy_generator(gen)
>>> regen
<unipy.utils.generator.ReusableGenerator object at 0x1061a97f0>
>>> list(regen)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> list(regen)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> list(gen)  # Once the copied one is used, the source will be exhausted.
[]
>>> list(gen)
[]
>>> list(regen)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> list(regen)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

unipy.utils.generator.split_generator(iterable, size)[source]¶

unipy.utils.generator.num_fromto_generator(start, end, term)[source]¶

A range function yields pair chunks.

It had made for time-formatting query. It yields a tuple of (start, start+(term-1)) pair, until start > end.

Parameters: *args (int) – end or start, end[, term] It works like range function.
Yields: tuple – A tuple of (start, start+(term-1)) pair, until start > end.

See also

yield

Examples

>>> from unipy.utils.generator import num_fromto_generator
>>>
>>> query = 'BETWEEN {pre} AND {nxt};'
>>>
>>> q_list = [query.format(pre=item[0], nxt=item[1])
...           for item in num_fromto_generator(1, 100, 10)]
>>> print(q_list[0])
BETWEEN 1 AND 10;
>>> print(q_list[1])
BETWEEN 11 AND 20;

unipy.utils.generator.dt_fromto_generator(start, end, day_term, tm_format='%Y%m%d')[source]¶

A range function yields datetime formats by pair.

It had made for time-formatting query. It yields a tuple of (start, start+(term-1)) pair, until start > end.

Parameters

start (str) – start datetime like ‘yyyymmdd’.
end (str) – start datetime like ‘yyyymmdd’.
day_term (int) – term of days.
tm_format ((default: '%Y%m%d')) – datetime format string.

Yields

tuple – A tuple of (start, start+(term-1)) pair, until start > end.

See also

yield

Examples

>>> from unipy.utils.generator import dt_fromto_generator
>>> dt_list = [item for item in
...            dt_fromto_generator('20170101','20170331', 10)]
>>> dt_list[:3]
[('20170101', '20170110'),
 ('20170111', '20170120'),
 ('20170121', '20170130')]

unipy.utils.generator.tm_fromto_generator(start, end, day_term, tm_string=['000000', '235959'], tm_format='%Y%m%d')[source]¶

A range function yields datetime formats by pair.

It had made for time-formatting query. It yields a tuple of (start, start+(term-1)) pair, until start > end.

Parameters

start (str) – start datetime like ‘yyyymmdd’.
end (str) – start datetime like ‘yyyymmdd’.
day_term (int) – term of days.
tm_string (list (default: ['000000', '235959'])) – time strings to concatenate.
tm_format ((default: '%Y%m%d')) – datetime format string.

Yields

tuple – A tuple of (start, start+(term-1)) pair, until start > end.

See also

yield

Examples

>>> from unipy.utils.generator import tm_fromto_generator
>>> tm_list = [item for item in
...            tm_fromto_generator('20170101','20170331', 10)]
>>> tm_list[:3]
[('20170101000000', '20170110235959'),
 ('20170111000000', '20170120235959'),
 ('20170121000000', '20170130235959')]

unipy.utils.generator.timestamp_generator(*args)[source]¶

A range function yields pair timestep strings.

It had made for time-formatting query. It yields a tuple of (start, start+(term-1)) pair, until start > end.

Parameters: *args (int) – end or start, end[, term] It works like range function.
Yields: tuple – A tuple of (start, start+(term-1)) pair, until start > end.

See also

yield

Examples

>>> from unipy.utils.generator import timestamp_generator
>>> timestamp_generator(1, 10, 2)
<generator object timestamp_generator at 0x10f519678>
>>> list(timestamp_generator(1, 14, 5))
[(1, 5), (6, 10), (11, 15)]
>>> begin, fin, period = 1, 10, 3
>>> list(timestamp_generator(begin, fin, period))
[(1, 3), (4, 6), (7, 9), (10, 12)]
>>> time_sequence = timestamp_generator(begin, fin, period)
>>> time_msg = "{start:2} to {end:2}, {term:2} days."
>>> for time in time_sequence:
... b, f = time
... print(time_msg.format(start=b, end=f, term=period))
...
 1 to  3,  3 days.
 4 to  6,  3 days.
 7 to  9,  3 days.
10 to 12,  3 days.