Programming/python
Module: itertools
_Sudal
2019. 3. 2. 11:06
반복자에 관한 함수들이 들어있는 모듈: itertools
Source: https://docs.python.org/3.7/library/itertools.html#itertools.groupby
무한 반복자:
반복자 | 인수 | 결과 | 예 |
|---|---|---|---|
count() | start, [step] | start, start+step, start+2*step, … | count(10) --> 10 11 12 1314 ... |
cycle() | p | p0, p1, … plast, p0, p1, … | cycle('ABCD') --> A B C DA B C D ... |
repeat() | elem [,n] | elem, elem, elem, … endlessly or up to n times | repeat(10, 3) --> 10 10 10 |
Iterators terminating on the shortest input sequence:
| 반복자 | 인수 | 결과 | 예 |
|---|---|---|---|
accumulate() | p [,func] | p0, p0+p1, p0+p1+p2, … | accumulate([1,2,3,4,5]) -->1 3 6 10 15 |
chain() | p, q, … | p0, p1, … plast, q0, q1, … | chain('ABC', 'DEF') --> A BC D E F |
chain.from_iterable() | iterable | p0, p1, … plast, q0, q1, … | chain.from_iterable(['ABC','DEF']) --> A B C D E F |
compress() | data, selectors | (d[0] if s[0]), (d[1] if s[1]), … | compress('ABCDEF',[1,0,1,0,1,1]) --> A C E F |
dropwhile() | pred, seq | seq[n], seq[n+1], starting when pred fails | dropwhile(lambda x: x<5,[1,4,6,4,1]) --> 6 4 1 |
filterfalse() | pred, seq | elements of seq where pred(elem) is false | filterfalse(lambda x: x%2,range(10)) --> 0 2 4 6 8 |
groupby() | iterable[, key] | sub-iterators grouped by value of key(v) | |
islice() | seq, [start,] stop [, step] | elements from seq[start:stop:step] | islice('ABCDEFG', 2, None)--> C D E F G |
starmap() | func, seq | func(*seq[0]), func(*seq[1]), … | starmap(pow, [(2,5), (3,2),(10,3)]) --> 32 9 1000 |
takewhile() | pred, seq | seq[0], seq[1], until pred fails | takewhile(lambda x: x<5,[1,4,6,4,1]) --> 1 4 |
tee() | it, n | it1, it2, … itn splits one iterator into n | |
zip_longest() | p, q, … | (p[0], q[0]), (p[1], q[1]), … | zip_longest('ABCD', 'xy',fillvalue='-') --> Ax By C-D- |
조합 반복자:
| Iterator | Arguments | Results |
|---|---|---|
product() | p, q, … [repeat=1] | cartesian product, equivalent to a nested for-loop |
permutations() | p[, r] | r-length tuples, all possible orderings, no repeated elements |
combinations() | p, r | r-length tuples, in sorted order, no repeated elements |
combinations_with_replacement() | p, r | r-length tuples, in sorted order, with repeated elements |
product('ABCD', repeat=2) | AA AB AC AD BA BB BC BD CA CB CCCD DA DB DC DD | |
permutations('ABCD', 2) | AB AC AD BA BC BD CA CB CD DA DBDC | |
combinations('ABCD', 2) | AB AC AD BC BD CD | |
combinations_with_replacement('ABCD',2) | AA AB AC AD BB BC BD CC CD DD |