For example, $ \ bmod 3 $
ns = range(30)
m = 3
list(zip(*zip(*[iter(ns)]*m)))
[(0, 3, 6, 9, 12, 15, 18, 21, 24, 27),
(1, 4, 7, 10, 13, 16, 19, 22, 25, 28),
(2, 5, 8, 11, 14, 17, 20, 23, 26, 29)]
Then, when divided by $ 3 $, the remainder can be divided into integers of $ 0 $, $ 1 $, and $ 2 $. If you plunge into a list that isn't a number, skip three contents into one chunk.
ls = list('abcdefghijkl')
m = 3
list(zip(*zip(*[iter(ls)]*m)))
[('a', 'd', 'g', 'j'), ('b', 'e', 'h', 'k'), ('c', 'f', 'i', 'l')]
I don't know if this notation seems cool, but let me briefly explain why it works. For example
s = list(range(12))
s
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
To divide into 4 by 3 numbers
list(zip(*[iter(s)]*3))
[(0, 1, 2), (3, 4, 5), (6, 7, 8), (9, 10, 11)]
I think that there is a method called, which is quite famous. Actually, it is written suddenly in zip function of official tutorial.
You can use an idiom to cluster the data series into groups of length n using> zip (* [iter (s)] * n).
If you take a closer look, you'll notice that if you plunge this result into the zip function, you'll end up with a three-skip list.
list(zip(*zip(*[iter(s)]*3)))
[(0, 3, 6, 9), (1, 4, 7, 10), (2, 5, 8, 11)]
However, with this method, if you try to divide a list of 10 numbers into 3 numbers, the odd part will be truncated.
list(zip(*[iter(list(range(10)))]*3)) #9 is truncated
[(0, 1, 2), (3, 4, 5), (6, 7, 8)]
This is the specification of the zip function. To avoid this, the zip_longest function is provided in ʻitertools`.
from itertools import zip_longest
list(zip_longest(*[iter(list(range(10)))]*3)) #None enters in odd places
[(0, 1, 2), (3, 4, 5), (6, 7, 8), (9, None, None)]
Use this to update cosets as well. Finally, there is a process to remove None, but be aware that tuple is immutable. In the end, it was a set of sets, like mathematics.
from itertools import zip_longest
ns = range(50)
m = 3
[{x for x in t if x != None} for t in zip(*zip_longest(*[iter(ns)]*m))]
[{0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48},
{1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31, 34, 37, 40, 43, 46, 49},
{2, 5, 8, 11, 14, 17, 20, 23, 26, 29, 32, 35, 38, 41, 44, 47}]
The zip function ~~ I don't really like the name ~~, but it's deep.
Recommended Posts