fe/postgresql/python/itertools.py at master · python-postgres/fe

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# .python.itertools

"""

itertools extensions

"""

import collections.abc

from itertools import cycle, islice

def interlace(*iters, next = next) -> collections.abc.Iterable:

"""

interlace(i1, i2, ..., in) -> (

i1-0, i2-0, ..., in-0,

i1-1, i2-1, ..., in-1,

i1-n, i2-n, ..., in-n,

)

"""

return map(next, cycle([iter(x) for x in iters]))

def chunk(iterable, chunksize = 256):

"""

Given an iterable, return an iterable producing chunks of the objects

produced by the given iterable.

chunks([o1,o2,o3,o4], chunksize = 2) -> [

[o1,o2],

[o3,o4],

]

"""

iterable = iter(iterable)

last = ()

lastsize = chunksize

while lastsize == chunksize:

last = list(islice(iterable, chunksize))

lastsize = len(last)

yield last

def find(iterable, selector):

"""

Return the first item in the `iterable` that causes the `selector` to return

`True`.

"""

for x in iterable:

if selector(x):

return x