@@ -1188,6 +1188,8 @@ msgid ""
11881188"If the input is an iterator, then fully consuming the *islice* advances the "
11891189"input iterator by ``max(start, stop)`` steps regardless of the *step* value."
11901190msgstr ""
1191+ "若輸入為疊代器,則完整耗盡 *islice* 會使輸入的疊代器向前移動 ``max(start, "
1192+ "stop)`` 步,與 *step* 的值無關。"
11911193
11921194#: ../../library/itertools.rst:513
11931195msgid "Return successive overlapping pairs taken from the input *iterable*."
@@ -1332,6 +1334,8 @@ msgid ""
13321334"`Cartesian product <https://en.wikipedia.org/wiki/Cartesian_product>`_ of "
13331335"the input iterables."
13341336msgstr ""
1337+ "輸入可疊代物的 `笛卡爾乘積 <https://en.wikipedia.org/wiki/"
1338+ "Cartesian_product>`_"
13351339
13361340#: ../../library/itertools.rst:592
13371341msgid ""
@@ -1601,10 +1605,14 @@ msgid ""
16011605"`tee` calls to share the same underlying data chain and to have a single "
16021606"update step rather than a chain of calls."
16031607msgstr ""
1608+ "當輸入的 *iterable* 已經是一個 tee 疊代物件時,回傳的 tuple(元組)中所有成員"
1609+ "都會被建立,就如同它們是由上游的 :func:`tee` 呼叫所產生的一樣。這個「展平步"
1610+ "驟 (flattening step)」讓巢狀的 :func:`tee` 呼叫能共享相同的底層資料鏈,並以單"
1611+ "一的更新步驟取代一連串的呼叫。"
16041612
16051613#: ../../library/itertools.rst:734
16061614msgid "The flattening property makes tee iterators efficiently peekable:"
1607- msgstr ""
1615+ msgstr "展平特性讓 tee 疊代器具備高效的預覽能力: "
16081616
16091617#: ../../library/itertools.rst:736
16101618msgid ""
@@ -1613,6 +1621,10 @@ msgid ""
16131621" [forked_iterator] = tee(tee_iterator, 1)\n"
16141622" return next(forked_iterator)"
16151623msgstr ""
1624+ "def lookahead(tee_iterator):\n"
1625+ "\" 回傳下一個值,但不推進輸入\" \n"
1626+ " [forked_iterator] = tee(tee_iterator, 1)\n"
1627+ " return next(forked_iterator)"
16161628
16171629#: ../../library/itertools.rst:743
16181630msgid ""
@@ -1969,6 +1981,171 @@ msgid ""
19691981" while True:\n"
19701982" yield function()"
19711983msgstr ""
1984+ "from collections import Counter, deque\n"
1985+ "from contextlib import suppress\n"
1986+ "from functools import reduce\n"
1987+ "from math import comb, prod, sumprod, isqrt\n"
1988+ "from operator import itemgetter, getitem, mul, neg\n"
1989+ "\n"
1990+ "def take(n, iterable):\n"
1991+ "\" 回傳可疊代物件的前 n 個元素為串列。\" \n"
1992+ " return list(islice(iterable, n))\n"
1993+ "\n"
1994+ "def prepend(value, iterable):\n"
1995+ "\" 在可疊代物件開頭插入單一值。\" \n"
1996+ " # prepend(1, [2, 3, 4]) → 1 2 3 4\n"
1997+ " return chain([value], iterable)\n"
1998+ "\n"
1999+ "def tabulate(function, start=0):\n"
2000+ "\" 回傳 function(0), function(1), ...\" \n"
2001+ " return map(function, count(start))\n"
2002+ "\n"
2003+ "def repeatfunc(function, times=None, *args):\n"
2004+ "\" 重複呼叫一個帶指定引數的函式。\" \n"
2005+ " if times is None:\n"
2006+ " return starmap(function, repeat(args))\n"
2007+ " return starmap(function, repeat(args, times))\n"
2008+ "\n"
2009+ "def flatten(list_of_lists):\n"
2010+ "\" 將巢狀結構攤平一層。\" \n"
2011+ " return chain.from_iterable(list_of_lists)\n"
2012+ "\n"
2013+ "def ncycles(iterable, n):\n"
2014+ "\" 回傳序列的元素重複 n 次。\" \n"
2015+ " return chain.from_iterable(repeat(tuple(iterable), n))\n"
2016+ "\n"
2017+ "def loops(n):\n"
2018+ "\" 執行 n 次的迴圈。類似 range(n) 但不建立整數序列。\" \n"
2019+ " # for _ in loops(100): ...\n"
2020+ " return repeat(None, n)\n"
2021+ "\n"
2022+ "def tail(n, iterable):\n"
2023+ "\" 回傳一個疊代器,疊代最後 n 個元素。\" \n"
2024+ " # tail(3, 'ABCDEFG') → E F G\n"
2025+ " return iter(deque(iterable, maxlen=n))\n"
2026+ "\n"
2027+ "def consume(iterator, n=None):\n"
2028+ "\" 將疊代器往前推進 n 步。如果 n 為 None,則完全消耗。\" \n"
2029+ " # 使用以 C 語言的速度消耗疊代器的函式。\n"
2030+ " if n is None:\n"
2031+ " deque(iterator, maxlen=0)\n"
2032+ " else:\n"
2033+ " next(islice(iterator, n, n), None)\n"
2034+ "\n"
2035+ "def nth(iterable, n, default=None):\n"
2036+ "\" 回傳第 n 個元素或預設值。\" \n"
2037+ " return next(islice(iterable, n, None), default)\n"
2038+ "\n"
2039+ "def quantify(iterable, predicate=bool):\n"
2040+ "\" 給定一個回傳 True 或 False 的判斷函式,計算為 True 的結果。\" \n"
2041+ " return sum(map(predicate, iterable))\n"
2042+ "\n"
2043+ "def first_true(iterable, default=False, predicate=None):\n"
2044+ "\" 回傳第一個為 true 的值,若無則回傳*預設值*。\" \n"
2045+ " # first_true([a,b,c], x) → a or b or c or x\n"
2046+ " # first_true([a,b], x, f) → a if f(a) else b if f(b) else x\n"
2047+ " return next(filter(predicate, iterable), default)\n"
2048+ "\n"
2049+ "def all_equal(iterable, key=None):\n"
2050+ "\" 回傳 True,如果所有元素兩兩相等。\" \n"
2051+ " # all_equal('4٤௪౪໔', key=int) → True\n"
2052+ " return len(take(2, groupby(iterable, key))) <= 1\n"
2053+ "\n"
2054+ "def unique_justseen(iterable, key=None):\n"
2055+ "\" 產生唯一的元素,並保留原始順序。只記住剛看見的元素。\" \n"
2056+ " # unique_justseen('AAAABBBCCDAABBB') → A B C D A B\n"
2057+ " # unique_justseen('ABBcCAD', str.casefold) → A B c A D\n"
2058+ " if key is None:\n"
2059+ " return map(itemgetter(0), groupby(iterable))\n"
2060+ " return map(next, map(itemgetter(1), groupby(iterable, key)))\n"
2061+ "\n"
2062+ "def unique_everseen(iterable, key=None):\n"
2063+ "\" 產生唯一的元素,並保留原始順序。記住所有曾見過的元素。\" \n"
2064+ " # unique_everseen('AAAABBBCCDAABBB') → A B C D\n"
2065+ " # unique_everseen('ABBcCAD', str.casefold) → A B c D\n"
2066+ " seen = set()\n"
2067+ " if key is None:\n"
2068+ " for element in filterfalse(seen.__contains__, iterable):\n"
2069+ " seen.add(element)\n"
2070+ " yield element\n"
2071+ " else:\n"
2072+ " for element in iterable:\n"
2073+ " k = key(element)\n"
2074+ " if k not in seen:\n"
2075+ " seen.add(k)\n"
2076+ " yield element\n"
2077+ "\n"
2078+ "def unique(iterable, key=None, reverse=False):\n"
2079+ "\" 產生排序後的不重複元素。支援不可雜湊的輸入。\" \n"
2080+ " # unique([[1, 2], [3, 4], [1, 2]]) → [1, 2] [3, 4]\n"
2081+ " sequenced = sorted(iterable, key=key, reverse=reverse)\n"
2082+ " return unique_justseen(sequenced, key=key)\n"
2083+ "\n"
2084+ "def sliding_window(iterable, n):\n"
2085+ "\" 將資料收集成重疊的固定長度區段或區塊。\" \n"
2086+ " # sliding_window('ABCDEFG', 4) → ABCD BCDE CDEF DEFG\n"
2087+ " iterator = iter(iterable)\n"
2088+ " window = deque(islice(iterator, n - 1), maxlen=n)\n"
2089+ " for x in iterator:\n"
2090+ " window.append(x)\n"
2091+ " yield tuple(window)\n"
2092+ "\n"
2093+ "def grouper(iterable, n, *, incomplete='fill', fillvalue=None):\n"
2094+ "\" 將資料收集成不重疊的固定長度區段或區塊。\" \n"
2095+ " # grouper('ABCDEFG', 3, fillvalue='x') → ABC DEF Gxx\n"
2096+ " # grouper('ABCDEFG', 3, incomplete='strict') → ABC DEF ValueError\n"
2097+ " # grouper('ABCDEFG', 3, incomplete='ignore') → ABC DEF\n"
2098+ " iterators = [iter(iterable)] * n\n"
2099+ " match incomplete:\n"
2100+ " case 'fill':\n"
2101+ " return zip_longest(*iterators, fillvalue=fillvalue)\n"
2102+ " case 'strict':\n"
2103+ " return zip(*iterators, strict=True)\n"
2104+ " case 'ignore':\n"
2105+ " return zip(*iterators)\n"
2106+ " case _:\n"
2107+ " raise ValueError('Expected fill, strict, or ignore')\n"
2108+ "\n"
2109+ "def roundrobin(*iterables):\n"
2110+ "\" 以循環方式依序輸入可疊代物件,直到全部耗盡。\" \n"
2111+ " # roundrobin('ABC', 'D', 'EF') → A D E B F C\n"
2112+ " # 演算法出自 George Sakkis\n"
2113+ " iterators = map(iter, iterables)\n"
2114+ " for num_active in range(len(iterables), 0, -1):\n"
2115+ " iterators = cycle(islice(iterators, num_active))\n"
2116+ " yield from map(next, iterators)\n"
2117+ "\n"
2118+ "def subslices(seq):\n"
2119+ "\" 回傳序列的所有連續非空子切片。\" \n"
2120+ " # subslices('ABCD') → A AB ABC ABCD B BC BCD C CD D\n"
2121+ " slices = starmap(slice, combinations(range(len(seq) + 1), 2))\n"
2122+ " return map(getitem, repeat(seq), slices)\n"
2123+ "\n"
2124+ "def iter_index(iterable, value, start=0, stop=None):\n"
2125+ "\" 回傳在序列或可疊代物件中某值出現的索引位置。\" \n"
2126+ " # iter_index('AABCADEAF', 'A') → 0 1 4 7\n"
2127+ " seq_index = getattr(iterable, 'index', None)\n"
2128+ " if seq_index is None:\n"
2129+ " iterator = islice(iterable, start, stop)\n"
2130+ " for i, element in enumerate(iterator, start):\n"
2131+ " if element is value or element == value:\n"
2132+ " yield i\n"
2133+ " else:\n"
2134+ " stop = len(iterable) if stop is None else stop\n"
2135+ " i = start\n"
2136+ " with suppress(ValueError):\n"
2137+ " while True:\n"
2138+ " yield (i := seq_index(value, i, stop))\n"
2139+ " i += 1\n"
2140+ "\n"
2141+ "def iter_except(function, exception, first=None):\n"
2142+ "\" 將一個 call-until-exception 轉換為疊代器介面。\" \n"
2143+ " # iter_except(d.popitem, KeyError) → 非阻塞的字典疊代器\n"
2144+ " with suppress(exception):\n"
2145+ " if first is not None:\n"
2146+ " yield first()\n"
2147+ " while True:\n"
2148+ " yield function()"
19722149
19732150#: ../../library/itertools.rst:1008
19742151msgid "The following recipes have a more mathematical flavor:"
@@ -2100,3 +2277,125 @@ msgid ""
21002277" n -= n // prime\n"
21012278" return n"
21022279msgstr ""
2280+ "def multinomial(*counts):\n"
2281+ "\" 多重集合的不同排列數。\" \n"
2282+ " # Counter('abracadabra').values() → 5 2 2 1 1\n"
2283+ " # multinomial(5, 2, 2, 1, 1) → 83160\n"
2284+ " return prod(map(comb, accumulate(counts), counts))\n"
2285+ "\n"
2286+ "def powerset(iterable):\n"
2287+ "\" 來自可疊代物件的子序列,從最短到最長。\" \n"
2288+ " # powerset([1,2,3]) → () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)\n"
2289+ " s = list(iterable)\n"
2290+ " return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))\n"
2291+ "\n"
2292+ "def sum_of_squares(iterable):\n"
2293+ "\" 將輸入值的平方加總。\" \n"
2294+ " # sum_of_squares([10, 20, 30]) → 1400\n"
2295+ " return sumprod(*tee(iterable))\n"
2296+ "\n"
2297+ "def reshape(matrix, columns):\n"
2298+ "\" 將 2 維矩陣重新塑形為指定的行數。\" \n"
2299+ " # reshape([(0, 1), (2, 3), (4, 5)], 3) → (0, 1, 2), (3, 4, 5)\n"
2300+ " return batched(chain.from_iterable(matrix), columns, strict=True)\n"
2301+ "\n"
2302+ "def transpose(matrix):\n"
2303+ "\" 交換 2 維矩陣的列和行。\" \n"
2304+ " # transpose([(1, 2, 3), (11, 22, 33)]) → (1, 11) (2, 22) (3, 33)\n"
2305+ " return zip(*matrix, strict=True)\n"
2306+ "\n"
2307+ "def matmul(m1, m2):\n"
2308+ "\" 矩陣相乘。\" \n"
2309+ " # matmul([(7, 5), (3, 5)], [(2, 5), (7, 9)]) → (49, 80), (41, 60)\n"
2310+ " n = len(m2[0])\n"
2311+ " return batched(starmap(sumprod, product(m1, transpose(m2))), n)\n"
2312+ "\n"
2313+ "def convolve(signal, kernel):\n"
2314+ "\"\"\" 兩個可疊代物件的離散線性捲積。\n"
2315+ " 等同於多項式相乘。\n"
2316+ "\n"
2317+ " 在數學上捲積是可交換的;但輸入的處理方式不同。\n"
2318+ " 訊號以惰性方式被讀取,且可以是無限;核心會在計算開始前被全部讀取。\n"
2319+ "\n"
2320+ " 文章:https://betterexplained.com/articles/intuitive-convolution/\n"
2321+ " 影片:https://www.youtube.com/watch?v=KuXjwB4LzSA\n"
2322+ "\"\"\" \n"
2323+ " # convolve([1, -1, -20], [1, -3]) → 1 -4 -17 60\n"
2324+ " # convolve(data, [0.25, 0.25, 0.25, 0.25]) → 移動平均(模糊)\n"
2325+ " # convolve(data, [1/2, 0, -1/2]) → 一階導數估計\n"
2326+ " # convolve(data, [1, -2, 1]) → 二階導數估計\n"
2327+ " kernel = tuple(kernel)[::-1]\n"
2328+ " n = len(kernel)\n"
2329+ " padded_signal = chain(repeat(0, n-1), signal, repeat(0, n-1))\n"
2330+ " windowed_signal = sliding_window(padded_signal, n)\n"
2331+ " return map(sumprod, repeat(kernel), windowed_signal)\n"
2332+ "\n"
2333+ "def polynomial_from_roots(roots):\n"
2334+ "\"\"\" 由多項式的根計算其係數。\n"
2335+ "\n"
2336+ " (x - 5) (x + 4) (x - 3) 展開為: x³ -4x² -17x + 60\n"
2337+ "\"\"\" \n"
2338+ " # polynomial_from_roots([5, -4, 3]) → [1, -4, -17, 60]\n"
2339+ " factors = zip(repeat(1), map(neg, roots))\n"
2340+ " return list(reduce(convolve, factors, [1]))\n"
2341+ "\n"
2342+ "def polynomial_eval(coefficients, x):\n"
2343+ "\"\"\" 在指定值計算多項式的值。\n"
2344+ "\n"
2345+ " 此方法在數值穩定性上比 Horner 方法更好。\n"
2346+ "\"\"\" \n"
2347+ " # 計算 x³ -4x² -17x + 60 在 x = 5 時的值\n"
2348+ " # polynomial_eval([1, -4, -17, 60], x=5) → 0\n"
2349+ " n = len(coefficients)\n"
2350+ " if not n:\n"
2351+ " return type(x)(0)\n"
2352+ " powers = map(pow, repeat(x), reversed(range(n)))\n"
2353+ " return sumprod(coefficients, powers)\n"
2354+ "\n"
2355+ "def polynomial_derivative(coefficients):\n"
2356+ "\"\"\" 計算多項式的一階導數。\n"
2357+ "\n"
2358+ " f(x) = x³ -4x² -17x + 60\n"
2359+ " f'(x) = 3x² -8x -17\n"
2360+ "\"\"\" \n"
2361+ " # polynomial_derivative([1, -4, -17, 60]) → [3, -8, -17]\n"
2362+ " n = len(coefficients)\n"
2363+ " powers = reversed(range(1, n))\n"
2364+ " return list(map(mul, coefficients, powers))\n"
2365+ "\n"
2366+ "def sieve(n):\n"
2367+ "\" 小於 n 的質數。\" \n"
2368+ " # sieve(30) → 2 3 5 7 11 13 17 19 23 29\n"
2369+ " if n > 2:\n"
2370+ " yield 2\n"
2371+ " data = bytearray((0, 1)) * (n // 2)\n"
2372+ " for p in iter_index(data, 1, start=3, stop=isqrt(n) + 1):\n"
2373+ " data[p*p : n : p+p] = bytes(len(range(p*p, n, p+p)))\n"
2374+ " yield from iter_index(data, 1, start=3)\n"
2375+ "\n"
2376+ "def factor(n):\n"
2377+ "\" n 的質因數。\" \n"
2378+ " # factor(99) → 3 3 11\n"
2379+ " # factor(1_000_000_000_000_007) → 47 59 360620266859\n"
2380+ " # factor(1_000_000_000_000_403) → 1000000000000403\n"
2381+ " for prime in sieve(isqrt(n) + 1):\n"
2382+ " while not n % prime:\n"
2383+ " yield prime\n"
2384+ " n //= prime\n"
2385+ " if n == 1:\n"
2386+ " return\n"
2387+ " if n > 1:\n"
2388+ " yield n\n"
2389+ "\n"
2390+ "def is_prime(n):\n"
2391+ "\" 回傳 True,若 n 為質數。\" \n"
2392+ " # is_prime(1_000_000_000_000_403) → True\n"
2393+ " return n > 1 and next(factor(n)) == n\n"
2394+ "\n"
2395+ "def totient(n):\n"
2396+ "\" 計算不大於 n 且與 n 互質的自然數個數。\" \n"
2397+ " # https://mathworld.wolfram.com/TotientFunction.html\n"
2398+ " # totient(12) → 4 因爲 len([1, 5, 7, 11]) == 4\n"
2399+ " for prime in set(factor(n)):\n"
2400+ " n -= n // prime\n"
2401+ " return n"