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GeezerVison is showing github.com — python-docs-zh-cn/tutorial/datastructures.po at 3.12 · python/python-docs-zh-cn Expand file tree/ Copy pathdatastructures.poMore file actions 1337 lines (1212 loc) · 52.6 KB / Copy pathdatastructures.poFile metadata and controls1337 lines (1212 loc) · 52.6 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 # SOME DESCRIPTIVE TITLE. # Copyright (C) 2001-2026, Python Software Foundation # This file is distributed under the same license as the Python package. # FIRST AUTHOR <EMAIL@ADDRESS>, YEAR. # # Translators: # Rafael Fontenelle <[email protected]>, 2025 # zhoubo, 2026 # #, fuzzy msgid "" msgstr "" "Project-Id-Version: Python 3.12\n" "Report-Msgid-Bugs-To: \n" "POT-Creation-Date: 2026-11-05 23:31+0000\n" "PO-Revision-Date: 2025-07-18 19:59+0000\n" "Last-Translator: zhoubo, 2026\n" "Language-Team: Chinese (China) (https://app.transifex.com/python-doc/teams/5390/zh_CN/)\n" "MIME-Version: 1.0\n" "Content-Type: text/plain; charset=UTF-8\n" "Content-Transfer-Encoding: 8bit\n" "Language: zh_CN\n" "Plural-Forms: nplurals=1; plural=0;\n" #: ../../tutorial/datastructures.rst:5 msgid "Data Structures" msgstr "数据结构" #: ../../tutorial/datastructures.rst:7 msgid "" "This chapter describes some things you've learned about already in more " "detail, and adds some new things as well." msgstr "本章深入讲解之前学过的一些内容，同时，还增加了新的知识点。" #: ../../tutorial/datastructures.rst:13 msgid "More on Lists" msgstr "列表详解" #: ../../tutorial/datastructures.rst:15 msgid "" "The list data type has some more methods. Here are all of the methods of " "list objects:" msgstr "列表数据类型支持很多方法，列表对象的所有方法所示如下：" #: ../../tutorial/datastructures.rst:22 msgid "Add an item to the end of the list. Similar to ``a[len(a):] = [x]``." msgstr "在列表末尾添加一项。 类似于 ``a[len(a):] = [x]``。" #: ../../tutorial/datastructures.rst:28 msgid "" "Extend the list by appending all the items from the iterable. Similar to " "``a[len(a):] = iterable``." msgstr "通过添加来自 iterable 的所有项来扩展列表。 类似于 ``a[len(a):] = iterable``。" #: ../../tutorial/datastructures.rst:35 msgid "" "Insert an item at a given position. The first argument is the index of the " "element before which to insert, so ``a.insert(0, x)`` inserts at the front " "of the list, and ``a.insert(len(a), x)`` is equivalent to ``a.append(x)``." msgstr "" "在指定位置插入元素。第一个参数是插入元素的索引，因此，``a.insert(0, x)`` 在列表开头插入元素， ``a.insert(len(a), " "x)`` 等同于 ``a.append(x)`` 。" #: ../../tutorial/datastructures.rst:43 msgid "" "Remove the first item from the list whose value is equal to *x*. It raises " "a :exc:`ValueError` if there is no such item." msgstr "从列表中删除第一个值为 *x* 的元素。未找到指定元素时，触发 :exc:`ValueError` 异常。" #: ../../tutorial/datastructures.rst:50 msgid "" "Remove the item at the given position in the list, and return it. If no " "index is specified, ``a.pop()`` removes and returns the last item in the " "list. It raises an :exc:`IndexError` if the list is empty or the index is " "outside the list range." msgstr "" "移除列表中给定位置上的条目，并返回该条目。 如果未指定索引号，则 ``a.pop()`` 将移除并返回列表中的最后一个条目。 " "如果列表为空或索引号在列表索引范围之外则会引发 :exc:`IndexError`。" #: ../../tutorial/datastructures.rst:59 msgid "Remove all items from the list. Similar to ``del a[:]``." msgstr "移除列表中的所有项。 类似于 ``del a[:]``。" #: ../../tutorial/datastructures.rst:65 msgid "" "Return zero-based index in the list of the first item whose value is equal " "to *x*. Raises a :exc:`ValueError` if there is no such item." msgstr "返回列表中第一个值为 *x* 的元素的零基索引。未找到指定元素时，触发 :exc:`ValueError` 异常。" #: ../../tutorial/datastructures.rst:68 msgid "" "The optional arguments *start* and *end* are interpreted as in the slice " "notation and are used to limit the search to a particular subsequence of the" " list. The returned index is computed relative to the beginning of the full" " sequence rather than the *start* argument." msgstr "" "可选参数 *start* 和 *end* 是切片符号，用于将搜索限制为列表的特定子序列。返回的索引是相对于整个序列的开始计算的，而不是 *start* " "参数。" #: ../../tutorial/datastructures.rst:77 msgid "Return the number of times *x* appears in the list." msgstr "返回列表中元素 *x* 出现的次数。" #: ../../tutorial/datastructures.rst:83 msgid "" "Sort the items of the list in place (the arguments can be used for sort " "customization, see :func:`sorted` for their explanation)." msgstr "原地排序列表中的元素 (要了解自定义排序参数，详见 :func:`sorted`)。" #: ../../tutorial/datastructures.rst:90 msgid "Reverse the elements of the list in place." msgstr "翻转列表中的元素。" #: ../../tutorial/datastructures.rst:96 msgid "Return a shallow copy of the list. Similar to ``a[:]``." msgstr "返回列表的浅拷贝。 类似于 ``a[:]``。" #: ../../tutorial/datastructures.rst:99 msgid "An example that uses most of the list methods::" msgstr "多数列表方法示例：" #: ../../tutorial/datastructures.rst:101 msgid "" ">>> fruits = ['orange', 'apple', 'pear', 'banana', 'kiwi', 'apple', 'banana']\n" ">>> fruits.count('apple')\n" "2\n" ">>> fruits.count('tangerine')\n" "0\n" ">>> fruits.index('banana')\n" "3\n" ">>> fruits.index('banana', 4) # Find next banana starting at position 4\n" "6\n" ">>> fruits.reverse()\n" ">>> fruits\n" "['banana', 'apple', 'kiwi', 'banana', 'pear', 'apple', 'orange']\n" ">>> fruits.append('grape')\n" ">>> fruits\n" "['banana', 'apple', 'kiwi', 'banana', 'pear', 'apple', 'orange', 'grape']\n" ">>> fruits.sort()\n" ">>> fruits\n" "['apple', 'apple', 'banana', 'banana', 'grape', 'kiwi', 'orange', 'pear']\n" ">>> fruits.pop()\n" "'pear'" msgstr "" ">>> fruits = ['orange', 'apple', 'pear', 'banana', 'kiwi', 'apple', 'banana']\n" ">>> fruits.count('apple')\n" "2\n" ">>> fruits.count('tangerine')\n" "0\n" ">>> fruits.index('banana')\n" "3\n" ">>> fruits.index('banana', 4) # 从 4 号位开始查找下一个 banana\n" "6\n" ">>> fruits.reverse()\n" ">>> fruits\n" "['banana', 'apple', 'kiwi', 'banana', 'pear', 'apple', 'orange']\n" ">>> fruits.append('grape')\n" ">>> fruits\n" "['banana', 'apple', 'kiwi', 'banana', 'pear', 'apple', 'orange', 'grape']\n" ">>> fruits.sort()\n" ">>> fruits\n" "['apple', 'apple', 'banana', 'banana', 'grape', 'kiwi', 'orange', 'pear']\n" ">>> fruits.pop()\n" "'pear'" #: ../../tutorial/datastructures.rst:122 msgid "" "You might have noticed that methods like ``insert``, ``remove`` or ``sort`` " "that only modify the list have no return value printed -- they return the " "default ``None``. [#]_ This is a design principle for all mutable data " "structures in Python." msgstr "" "你可能已经注意到 ``insert``, ``remove`` 或 ``sort`` 等仅修改列表的方法都不会打印返回值 -- 它们返回默认值 " "``None``。 [#]_ 这是适用于 Python 中所有可变数据结构的设计原则。" #: ../../tutorial/datastructures.rst:127 msgid "" "Another thing you might notice is that not all data can be sorted or " "compared. For instance, ``[None, 'hello', 10]`` doesn't sort because " "integers can't be compared to strings and ``None`` can't be compared to " "other types. Also, there are some types that don't have a defined ordering " "relation. For example, ``3+4j < 5+7j`` isn't a valid comparison." msgstr "" "你可能会注意到的另一件事是并非所有数据都可以排序或比较。 举例来说，``[None, 'hello', 10]`` 就不可排序因为整数不能与字符串比较而" " ``None`` 不能与其他类型比较。 此外，还存在一些没有定义顺序关系的类型。 例如，``3+4j < 5+7j`` 就不是一个合法的比较。" #: ../../tutorial/datastructures.rst:138 msgid "Using Lists as Stacks" msgstr "用列表实现堆栈" #: ../../tutorial/datastructures.rst:143 msgid "" "The list methods make it very easy to use a list as a stack, where the last " "element added is the first element retrieved (\"last-in, first-out\"). To " "add an item to the top of the stack, use :meth:`!append`. To retrieve an " "item from the top of the stack, use :meth:`!pop` without an explicit index." " For example::" msgstr "" "列表方法使得将列表用作栈非常容易，最后添加的元素会最先被取出（“后进先出”）。 要将一个条目添加到栈顶，可使用 :meth:`!append`。 " "要从栈顶取出一个条目，则使用 :meth:`!pop` 且不必显式指定索引。 例如::" #: ../../tutorial/datastructures.rst:148 msgid "" ">>> stack = [3, 4, 5]\n" ">>> stack.append(6)\n" ">>> stack.append(7)\n" ">>> stack\n" "[3, 4, 5, 6, 7]\n" ">>> stack.pop()\n" "7\n" ">>> stack\n" "[3, 4, 5, 6]\n" ">>> stack.pop()\n" "6\n" ">>> stack.pop()\n" "5\n" ">>> stack\n" "[3, 4]" msgstr "" ">>> stack = [3, 4, 5]\n" ">>> stack.append(6)\n" ">>> stack.append(7)\n" ">>> stack\n" "[3, 4, 5, 6, 7]\n" ">>> stack.pop()\n" "7\n" ">>> stack\n" "[3, 4, 5, 6]\n" ">>> stack.pop()\n" "6\n" ">>> stack.pop()\n" "5\n" ">>> stack\n" "[3, 4]" #: ../../tutorial/datastructures.rst:168 msgid "Using Lists as Queues" msgstr "用列表实现队列" #: ../../tutorial/datastructures.rst:172 msgid "" "It is also possible to use a list as a queue, where the first element added " "is the first element retrieved (\"first-in, first-out\"); however, lists are" " not efficient for this purpose. While appends and pops from the end of " "list are fast, doing inserts or pops from the beginning of a list is slow " "(because all of the other elements have to be shifted by one)." msgstr "" "列表也可以用作队列，最先加入的元素，最先取出（“先进先出”）；然而，列表作为队列的效率很低。因为，在列表末尾添加和删除元素非常快，但在列表开头插入或移除元素却很慢（因为所有其他元素都必须移动一位）。" #: ../../tutorial/datastructures.rst:178 msgid "" "To implement a queue, use :class:`collections.deque` which was designed to " "have fast appends and pops from both ends. For example::" msgstr "实现队列最好用 :class:`collections.deque`，可以快速从两端添加或删除元素。例如：" #: ../../tutorial/datastructures.rst:181 msgid "" ">>> from collections import deque\n" ">>> queue = deque([\"Eric\", \"John\", \"Michael\"])\n" ">>> queue.append(\"Terry\") # Terry arrives\n" ">>> queue.append(\"Graham\") # Graham arrives\n" ">>> queue.popleft() # The first to arrive now leaves\n" "'Eric'\n" ">>> queue.popleft() # The second to arrive now leaves\n" "'John'\n" ">>> queue # Remaining queue in order of arrival\n" "deque(['Michael', 'Terry', 'Graham'])" msgstr "" ">>> from collections import deque\n" ">>> queue = deque([\"Eric\", \"John\", \"Michael\"])\n" ">>> queue.append(\"Terry\") # Terry 到了\n" ">>> queue.append(\"Graham\") # Graham 到了\n" ">>> queue.popleft() # 第一个到的现在走了\n" "'Eric'\n" ">>> queue.popleft() # 第二个到的现在走了\n" "'John'\n" ">>> queue # 按到达顺序排列的剩余队列\n" "deque(['Michael', 'Terry', 'Graham'])" #: ../../tutorial/datastructures.rst:196 msgid "List Comprehensions" msgstr "列表推导式" #: ../../tutorial/datastructures.rst:198 msgid "" "List comprehensions provide a concise way to create lists. Common " "applications are to make new lists where each element is the result of some " "operations applied to each member of another sequence or iterable, or to " "create a subsequence of those elements that satisfy a certain condition." msgstr "" "列表推导式创建列表的方式更简洁。常见的用法为，对序列或可迭代对象中的每个元素应用某种操作，用生成的结果创建新的列表；或用满足特定条件的元素创建子序列。" #: ../../tutorial/datastructures.rst:203 msgid "For example, assume we want to create a list of squares, like::" msgstr "例如，创建平方值的列表：" #: ../../tutorial/datastructures.rst:205 msgid "" ">>> squares = []\n" ">>> for x in range(10):\n" "... squares.append(x**2)\n" "...\n" ">>> squares\n" "[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]" msgstr "" ">>> squares = []\n" ">>> for x in range(10):\n" "... squares.append(x**2)\n" "...\n" ">>> squares\n" "[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]" #: ../../tutorial/datastructures.rst:212 msgid "" "Note that this creates (or overwrites) a variable named ``x`` that still " "exists after the loop completes. We can calculate the list of squares " "without any side effects using::" msgstr "注意，这段代码创建（或覆盖）变量 ``x``，该变量在循环结束后仍然存在。下述方法可以无副作用地计算平方列表：" #: ../../tutorial/datastructures.rst:216 msgid "squares = list(map(lambda x: x**2, range(10)))" msgstr "squares = list(map(lambda x: x**2, range(10)))" #: ../../tutorial/datastructures.rst:218 msgid "or, equivalently::" msgstr "或等价于：" #: ../../tutorial/datastructures.rst:220 msgid "squares = [x**2 for x in range(10)]" msgstr "squares = [x**2 for x in range(10)]" #: ../../tutorial/datastructures.rst:222 msgid "which is more concise and readable." msgstr "上面这种写法更简洁、易读。" #: ../../tutorial/datastructures.rst:224 msgid "" "A list comprehension consists of brackets containing an expression followed " "by a :keyword:`!for` clause, then zero or more :keyword:`!for` or " ":keyword:`!if` clauses. The result will be a new list resulting from " "evaluating the expression in the context of the :keyword:`!for` and " ":keyword:`!if` clauses which follow it. For example, this listcomp combines " "the elements of two lists if they are not equal::" msgstr "" "列表推导式的方括号内包含以下内容：一个表达式，后面为一个 :keyword:`!for` 子句，然后，是零个或多个 :keyword:`!for` 或 " ":keyword:`!if` 子句。结果是由表达式依据 :keyword:`!for` 和 :keyword:`!if` 子句求值计算而得出一个新列表。" " 举例来说，以下列表推导式将两个列表中不相等的元素组合起来：" #: ../../tutorial/datastructures.rst:231 msgid "" ">>> [(x, y) for x in [1,2,3] for y in [3,1,4] if x != y]\n" "[(1, 3), (1, 4), (2, 3), (2, 1), (2, 4), (3, 1), (3, 4)]" msgstr "" ">>> [(x, y) for x in [1,2,3] for y in [3,1,4] if x != y]\n" "[(1, 3), (1, 4), (2, 3), (2, 1), (2, 4), (3, 1), (3, 4)]" #: ../../tutorial/datastructures.rst:234 msgid "and it's equivalent to::" msgstr "等价于：" #: ../../tutorial/datastructures.rst:236 msgid "" ">>> combs = []\n" ">>> for x in [1,2,3]:\n" "... for y in [3,1,4]:\n" "... if x != y:\n" "... combs.append((x, y))\n" "...\n" ">>> combs\n" "[(1, 3), (1, 4), (2, 3), (2, 1), (2, 4), (3, 1), (3, 4)]" msgstr "" ">>> combs = []\n" ">>> for x in [1,2,3]:\n" "... for y in [3,1,4]:\n" "... if x != y:\n" "... combs.append((x, y))\n" "...\n" ">>> combs\n" "[(1, 3), (1, 4), (2, 3), (2, 1), (2, 4), (3, 1), (3, 4)]" #: ../../tutorial/datastructures.rst:245 msgid "" "Note how the order of the :keyword:`for` and :keyword:`if` statements is the" " same in both these snippets." msgstr "注意，上面两段代码中，:keyword:`for` 和 :keyword:`if` 的顺序相同。" #: ../../tutorial/datastructures.rst:248 msgid "" "If the expression is a tuple (e.g. the ``(x, y)`` in the previous example), " "it must be parenthesized. ::" msgstr "表达式是元组 (例如上例的 ``(x, y)``) 时，必须加上圆括号。::" #: ../../tutorial/datastructures.rst:251 msgid "" ">>> vec = [-4, -2, 0, 2, 4]\n" ">>> # create a new list with the values doubled\n" ">>> [x*2 for x in vec]\n" "[-8, -4, 0, 4, 8]\n" ">>> # filter the list to exclude negative numbers\n" ">>> [x for x in vec if x >= 0]\n" "[0, 2, 4]\n" ">>> # apply a function to all the elements\n" ">>> [abs(x) for x in vec]\n" "[4, 2, 0, 2, 4]\n" ">>> # call a method on each element\n" ">>> freshfruit = [' banana', ' loganberry ', 'passion fruit ']\n" ">>> [weapon.strip() for weapon in freshfruit]\n" "['banana', 'loganberry', 'passion fruit']\n" ">>> # create a list of 2-tuples like (number, square)\n" ">>> [(x, x**2) for x in range(6)]\n" "[(0, 0), (1, 1), (2, 4), (3, 9), (4, 16), (5, 25)]\n" ">>> # the tuple must be parenthesized, otherwise an error is raised\n" ">>> [x, x**2 for x in range(6)]\n" " File \"<stdin>\", line 1\n" " [x, x**2 for x in range(6)]\n" " ^^^^^^^\n" "SyntaxError: did you forget parentheses around the comprehension target?\n" ">>> # flatten a list using a listcomp with two 'for'\n" ">>> vec = [[1,2,3], [4,5,6], [7,8,9]]\n" ">>> [num for elem in vec for num in elem]\n" "[1, 2, 3, 4, 5, 6, 7, 8, 9]" msgstr "" ">>> vec = [-4, -2, 0, 2, 4]\n" ">>> # 新建一个将值翻倍的列表\n" ">>> [x*2 for x in vec]\n" "[-8, -4, 0, 4, 8]\n" ">>> # 过滤列表以排除负数\n" ">>> [x for x in vec if x >= 0]\n" "[0, 2, 4]\n" ">>> # 对所有元素应用一个函数\n" ">>> [abs(x) for x in vec]\n" "[4, 2, 0, 2, 4]\n" ">>> # 在每个元素上调用一个方法\n" ">>> freshfruit = [' banana', ' loganberry ', 'passion fruit ']\n" ">>> [weapon.strip() for weapon in freshfruit]\n" "['banana', 'loganberry', 'passion fruit']\n" ">>> # 创建一个包含 (数字, 平方) 2 元组的列表\n" ">>> [(x, x**2) for x in range(6)]\n" "[(0, 0), (1, 1), (2, 4), (3, 9), (4, 16), (5, 25)]\n" ">>> # 元组必须加圆括号，否则会引发错误\n" ">>> [x, x**2 for x in range(6)]\n" " File \"<stdin>\", line 1\n" " [x, x**2 for x in range(6)]\n" " ^^^^^^^\n" "SyntaxError: did you forget parentheses around the comprehension target?\n" ">>> # 使用两个 'for' 来展平嵌套的列表\n" ">>> vec = [[1,2,3], [4,5,6], [7,8,9]]\n" ">>> [num for elem in vec for num in elem]\n" "[1, 2, 3, 4, 5, 6, 7, 8, 9]" #: ../../tutorial/datastructures.rst:279 msgid "" "List comprehensions can contain complex expressions and nested functions::" msgstr "列表推导式可以使用复杂的表达式和嵌套函数：" #: ../../tutorial/datastructures.rst:281 msgid "" ">>> from math import pi\n" ">>> [str(round(pi, i)) for i in range(1, 6)]\n" "['3.1', '3.14', '3.142', '3.1416', '3.14159']" msgstr "" ">>> from math import pi\n" ">>> [str(round(pi, i)) for i in range(1, 6)]\n" "['3.1', '3.14', '3.142', '3.1416', '3.14159']" #: ../../tutorial/datastructures.rst:286 msgid "Nested List Comprehensions" msgstr "嵌套的列表推导式" #: ../../tutorial/datastructures.rst:288 msgid "" "The initial expression in a list comprehension can be any arbitrary " "expression, including another list comprehension." msgstr "列表推导式中的初始表达式可以是任何表达式，甚至可以是另一个列表推导式。" #: ../../tutorial/datastructures.rst:291 msgid "" "Consider the following example of a 3x4 matrix implemented as a list of 3 " "lists of length 4::" msgstr "下面这个 3x4 矩阵，由 3 个长度为 4 的列表组成：" #: ../../tutorial/datastructures.rst:294 msgid "" ">>> matrix = [\n" "... [1, 2, 3, 4],\n" "... [5, 6, 7, 8],\n" "... [9, 10, 11, 12],\n" "... ]" msgstr "" ">>> matrix = [\n" "... [1, 2, 3, 4],\n" "... [5, 6, 7, 8],\n" "... [9, 10, 11, 12],\n" "... ]" #: ../../tutorial/datastructures.rst:300 msgid "The following list comprehension will transpose rows and columns::" msgstr "下面的列表推导式可以转置行列：" #: ../../tutorial/datastructures.rst:302 msgid "" ">>> [[row[i] for row in matrix] for i in range(4)]\n" "[[1, 5, 9], [2, 6, 10], [3, 7, 11], [4, 8, 12]]" msgstr "" ">>> [[row[i] for row in matrix] for i in range(4)]\n" "[[1, 5, 9], [2, 6, 10], [3, 7, 11], [4, 8, 12]]" #: ../../tutorial/datastructures.rst:305 msgid "" "As we saw in the previous section, the inner list comprehension is evaluated" " in the context of the :keyword:`for` that follows it, so this example is " "equivalent to::" msgstr "如我们在之前小节中看到的，内部的列表推导式是在它之后的 :keyword:`for` 的上下文中被求值的，所以这个例子等价于::" #: ../../tutorial/datastructures.rst:309 msgid "" ">>> transposed = []\n" ">>> for i in range(4):\n" "... transposed.append([row[i] for row in matrix])\n" "...\n" ">>> transposed\n" "[[1, 5, 9], [2, 6, 10], [3, 7, 11], [4, 8, 12]]" msgstr "" ">>> transposed = []\n" ">>> for i in range(4):\n" "... transposed.append([row[i] for row in matrix])\n" "...\n" ">>> transposed\n" "[[1, 5, 9], [2, 6, 10], [3, 7, 11], [4, 8, 12]]" #: ../../tutorial/datastructures.rst:316 msgid "which, in turn, is the same as::" msgstr "反过来说，也等价于：" #: ../../tutorial/datastructures.rst:318 msgid "" ">>> transposed = []\n" ">>> for i in range(4):\n" "... # the following 3 lines implement the nested listcomp\n" "... transposed_row = []\n" "... for row in matrix:\n" "... transposed_row.append(row[i])\n" "... transposed.append(transposed_row)\n" "...\n" ">>> transposed\n" "[[1, 5, 9], [2, 6, 10], [3, 7, 11], [4, 8, 12]]" msgstr "" ">>> transposed = []\n" ">>> for i in range(4):\n" "... # 以下 3 行实现了嵌套的列表推导式\n" "... transposed_row = []\n" "... for row in matrix:\n" "... transposed_row.append(row[i])\n" "... transposed.append(transposed_row)\n" "...\n" ">>> transposed\n" "[[1, 5, 9], [2, 6, 10], [3, 7, 11], [4, 8, 12]]" #: ../../tutorial/datastructures.rst:329 msgid "" "In the real world, you should prefer built-in functions to complex flow " "statements. The :func:`zip` function would do a great job for this use " "case::" msgstr "实际应用中，最好用内置函数替代复杂的流程语句。此时，:func:`zip` 函数更好用：" #: ../../tutorial/datastructures.rst:332 msgid "" ">>> list(zip(*matrix))\n" "[(1, 5, 9), (2, 6, 10), (3, 7, 11), (4, 8, 12)]" msgstr "" ">>> list(zip(*matrix))\n" "[(1, 5, 9), (2, 6, 10), (3, 7, 11), (4, 8, 12)]" #: ../../tutorial/datastructures.rst:335 msgid "" "See :ref:`tut-unpacking-arguments` for details on the asterisk in this line." msgstr "关于本行中星号的详细说明，参见 :ref:`tut-unpacking-arguments`。" #: ../../tutorial/datastructures.rst:340 msgid "The :keyword:`!del` statement" msgstr ":keyword:`!del` 语句" #: ../../tutorial/datastructures.rst:342 msgid "" "There is a way to remove an item from a list given its index instead of its " "value: the :keyword:`del` statement. This differs from the :meth:`!pop` " "method which returns a value. The :keyword:`!del` statement can also be " "used to remove slices from a list or clear the entire list (which we did " "earlier by assignment of an empty list to the slice). For example::" msgstr "" "可以按索引而不是按值从一个列表移除条目：即使用 :keyword:`del` 语句。 这不同于返回一个值的 :meth:`!pop` 方法。 " ":keyword:`!del` 语句还可被用来从列表移除切片或清空整个列表（之前我们通过将一个空列表赋值给切片实现此功能）。 例如::" #: ../../tutorial/datastructures.rst:348 msgid "" ">>> a = [-1, 1, 66.25, 333, 333, 1234.5]\n" ">>> del a[0]\n" ">>> a\n" "[1, 66.25, 333, 333, 1234.5]\n" ">>> del a[2:4]\n" ">>> a\n" "[1, 66.25, 1234.5]\n" ">>> del a[:]\n" ">>> a\n" "[]" msgstr "" ">>> a = [-1, 1, 66.25, 333, 333, 1234.5]\n" ">>> del a[0]\n" ">>> a\n" "[1, 66.25, 333, 333, 1234.5]\n" ">>> del a[2:4]\n" ">>> a\n" "[1, 66.25, 1234.5]\n" ">>> del a[:]\n" ">>> a\n" "[]" #: ../../tutorial/datastructures.rst:359 msgid ":keyword:`del` can also be used to delete entire variables::" msgstr ":keyword:`del` 也可以用来删除整个变量：" #: ../../tutorial/datastructures.rst:361 msgid ">>> del a" msgstr ">>> del a" #: ../../tutorial/datastructures.rst:363 msgid "" "Referencing the name ``a`` hereafter is an error (at least until another " "value is assigned to it). We'll find other uses for :keyword:`del` later." msgstr "此后，再引用 ``a`` 就会报错（直到为它赋与另一个值）。后文会介绍 :keyword:`del` 的其他用法。" #: ../../tutorial/datastructures.rst:370 msgid "Tuples and Sequences" msgstr "元组和序列" #: ../../tutorial/datastructures.rst:372 msgid "" "We saw that lists and strings have many common properties, such as indexing " "and slicing operations. They are two examples of *sequence* data types (see" " :ref:`typesseq`). Since Python is an evolving language, other sequence " "data types may be added. There is also another standard sequence data type:" " the *tuple*." msgstr "" "列表和字符串有很多共性，例如，索引和切片操作。 这两种数据类型是 *序列* (参见 :ref:`typesseq`)。 随着 Python " "语言的发展，其他的序列类型也被加入其中。 本节介绍另一种标准序列类型: *元组*。" #: ../../tutorial/datastructures.rst:378 msgid "" "A tuple consists of a number of values separated by commas, for instance::" msgstr "元组由多个用逗号隔开的值组成，例如：" #: ../../tutorial/datastructures.rst:380 msgid "" ">>> t = 12345, 54321, 'hello!'\n" ">>> t[0]\n" "12345\n" ">>> t\n" "(12345, 54321, 'hello!')\n" ">>> # Tuples may be nested:\n" ">>> u = t, (1, 2, 3, 4, 5)\n" ">>> u\n" "((12345, 54321, 'hello!'), (1, 2, 3, 4, 5))\n" ">>> # Tuples are immutable:\n" ">>> t[0] = 88888\n" "Traceback (most recent call last):\n" " File \"<stdin>\", line 1, in <module>\n" "TypeError: 'tuple' object does not support item assignment\n" ">>> # but they can contain mutable objects:\n" ">>> v = ([1, 2, 3], [3, 2, 1])\n" ">>> v\n" "([1, 2, 3], [3, 2, 1])" msgstr "" ">>> t = 12345, 54321, 'hello!'\n" ">>> t[0]\n" "12345\n" ">>> t\n" "(12345, 54321, 'hello!')\n" ">>> # 元组可以嵌套：\n" ">>> u = t, (1, 2, 3, 4, 5)\n" ">>> u\n" "((12345, 54321, 'hello!'), (1, 2, 3, 4, 5))\n" ">>> # 元组是不可变对象：\n" ">>> t[0] = 88888\n" "Traceback (most recent call last):\n" " File \"<stdin>\", line 1, in <module>\n" "TypeError: 'tuple' object does not support item assignment\n" ">>> # 但它们可以包含可变对象：\n" ">>> v = ([1, 2, 3], [3, 2, 1])\n" ">>> v\n" "([1, 2, 3], [3, 2, 1])" #: ../../tutorial/datastructures.rst:400 msgid "" "As you see, on output tuples are always enclosed in parentheses, so that " "nested tuples are interpreted correctly; they may be input with or without " "surrounding parentheses, although often parentheses are necessary anyway (if" " the tuple is part of a larger expression). It is not possible to assign to" " the individual items of a tuple, however it is possible to create tuples " "which contain mutable objects, such as lists." msgstr "" "输出时，元组都要由圆括号标注，这样才能正确地解释嵌套元组。输入时，圆括号可有可无，不过经常是必须的（如果元组是更大的表达式的一部分）。不允许为元组中的单个元素赋值，当然，可以创建含列表等可变对象的元组。" #: ../../tutorial/datastructures.rst:407 msgid "" "Though tuples may seem similar to lists, they are often used in different " "situations and for different purposes. Tuples are :term:`immutable`, and " "usually contain a heterogeneous sequence of elements that are accessed via " "unpacking (see later in this section) or indexing (or even by attribute in " "the case of :func:`namedtuples <collections.namedtuple>`). Lists are " ":term:`mutable`, and their elements are usually homogeneous and are accessed" " by iterating over the list." msgstr "" "虽然，元组与列表很像，但使用场景不同，用途也不同。元组是 :term:`immutable` " "（不可变的），一般可包含异质元素序列，通过解包（见本节下文）或索引访问（如果是 :func:`namedtuples " "<collections.namedtuple>`，可以属性访问）。列表是 :term:`mutable` " "（可变的），列表元素一般为同质类型，可迭代访问。" #: ../../tutorial/datastructures.rst:415 msgid "" "A special problem is the construction of tuples containing 0 or 1 items: the" " syntax has some extra quirks to accommodate these. Empty tuples are " "constructed by an empty pair of parentheses; a tuple with one item is " "constructed by following a value with a comma (it is not sufficient to " "enclose a single value in parentheses). Ugly, but effective. For example::" msgstr "" "构造 0 个或 1 " "个元素的元组比较特殊：为了适应这种情况，对句法有一些额外的改变。用一对空圆括号就可以创建空元组；只有一个元素的元组可以通过在这个元素后添加逗号来构建（圆括号里只有一个值的话不够明确）。丑陋，但是有效。例如：" #: ../../tutorial/datastructures.rst:421 msgid "" ">>> empty = ()\n" ">>> singleton = 'hello', # <-- note trailing comma\n" ">>> len(empty)\n" "0\n" ">>> len(singleton)\n" "1\n" ">>> singleton\n" "('hello',)" msgstr "" ">>> empty = ()\n" ">>> singleton = 'hello', # <-- 注意末尾的逗号\n" ">>> len(empty)\n" "0\n" ">>> len(singleton)\n" "1\n" ">>> singleton\n" "('hello',)" #: ../../tutorial/datastructures.rst:430 msgid "" "The statement ``t = 12345, 54321, 'hello!'`` is an example of *tuple " "packing*: the values ``12345``, ``54321`` and ``'hello!'`` are packed " "together in a tuple. The reverse operation is also possible::" msgstr "" "语句 ``t = 12345, 54321, 'hello!'`` 是 *元组打包* 的例子：值 ``12345``, ``54321`` 和 " "``'hello!'`` 一起被打包进元组。逆操作也可以：" #: ../../tutorial/datastructures.rst:434 msgid ">>> x, y, z = t" msgstr ">>> x, y, z = t" #: ../../tutorial/datastructures.rst:436 msgid "" "This is called, appropriately enough, *sequence unpacking* and works for any" " sequence on the right-hand side. Sequence unpacking requires that there " "are as many variables on the left side of the equals sign as there are " "elements in the sequence. Note that multiple assignment is really just a " "combination of tuple packing and sequence unpacking." msgstr "" "称之为 *序列解包* " "也是妥妥的，适用于右侧的任何序列。序列解包时，左侧变量与右侧序列元素的数量应相等。注意，多重赋值其实只是元组打包和序列解包的组合。" #: ../../tutorial/datastructures.rst:446 msgid "Sets" msgstr "集合" #: ../../tutorial/datastructures.rst:448 msgid "" "Python also includes a data type for *sets*. A set is an unordered " "collection with no duplicate elements. Basic uses include membership " "testing and eliminating duplicate entries. Set objects also support " "mathematical operations like union, intersection, difference, and symmetric " "difference." msgstr "" "Python 还支持 *集合* " "这种数据类型。集合是由不重复元素组成的无序容器。基本用法包括成员检测、消除重复元素。集合对象支持合集、交集、差集、对称差分等数学运算。" #: ../../tutorial/datastructures.rst:453 msgid "" "Curly braces or the :func:`set` function can be used to create sets. Note: " "to create an empty set you have to use ``set()``, not ``{}``; the latter " "creates an empty dictionary, a data structure that we discuss in the next " "section." msgstr "" "创建集合用花括号或 :func:`set` 函数。注意，创建空集合只能用 ``set()``，不能用 ``{}``，``{}`` " "创建的是空字典，下一小节介绍数据结构：字典。" #: ../../tutorial/datastructures.rst:457 msgid "Here is a brief demonstration::" msgstr "以下是一些简单的示例 ::" #: ../../tutorial/datastructures.rst:459 msgid "" ">>> basket = {'apple', 'orange', 'apple', 'pear', 'orange', 'banana'}\n" ">>> print(basket) # show that duplicates have been removed\n" "{'orange', 'banana', 'pear', 'apple'}\n" ">>> 'orange' in basket # fast membership testing\n" "True\n" ">>> 'crabgrass' in basket\n" "False\n" "\n" ">>> # Demonstrate set operations on unique letters from two words\n" ">>>\n" ">>> a = set('abracadabra')\n" ">>> b = set('alacazam')\n" ">>> a # unique letters in a\n" "{'a', 'r', 'b', 'c', 'd'}\n" ">>> a - b # letters in a but not in b\n" "{'r', 'd', 'b'}\n" ">>> a | b # letters in a or b or both\n" "{'a', 'c', 'r', 'd', 'b', 'm', 'z', 'l'}\n" ">>> a & b # letters in both a and b\n" "{'a', 'c'}\n" ">>> a ^ b # letters in a or b but not both\n" "{'r', 'd', 'b', 'm', 'z', 'l'}" msgstr "" ">>> basket = {'apple', 'orange', 'apple', 'pear', 'orange', 'banana'}\n" ">>> print(basket) # 显示重复项已被移除\n" "{'orange', 'banana', 'pear', 'apple'}\n" ">>> 'orange' in basket # 快速成员检测\n" "True\n" ">>> 'crabgrass' in basket\n" "False\n" "\n" ">>> # 演示针对两个单词中独有的字母进行集合运算\n" ">>>\n" ">>> a = set('abracadabra')\n" ">>> b = set('alacazam')\n" ">>> a # a 中独有的字母\n" "{'a', 'r', 'b', 'c', 'd'}\n" ">>> a - b # 存在于 a 中但不存在于 b 中的字母\n" "{'r', 'd', 'b'}\n" ">>> a | b # 存在于 a 或 b 中或两者中皆有的字母\n" "{'a', 'c', 'r', 'd', 'b', 'm', 'z', 'l'}\n" ">>> a & b # 同时存在于 a 和 b 中的字母\n" "{'a', 'c'}\n" ">>> a ^ b # 存在于 a 或 b 中但非两者中皆有的字母\n" "{'r', 'd', 'b', 'm', 'z', 'l'}" #: ../../tutorial/datastructures.rst:482 msgid "" "Similarly to :ref:`list comprehensions <tut-listcomps>`, set comprehensions " "are also supported::" msgstr "与 :ref:`列表推导式 <tut-listcomps>` 类似，集合也支持推导式：" #: ../../tutorial/datastructures.rst:485 msgid "" ">>> a = {x for x in 'abracadabra' if x not in 'abc'}\n" ">>> a\n" "{'r', 'd'}" msgstr "" ">>> a = {x for x in 'abracadabra' if x not in 'abc'}\n" ">>> a\n" "{'r', 'd'}" #: ../../tutorial/datastructures.rst:493 msgid "Dictionaries" msgstr "字典" #: ../../tutorial/datastructures.rst:495 msgid "" "Another useful data type built into Python is the *dictionary* (see " ":ref:`typesmapping`). Dictionaries are sometimes found in other languages as" " \"associative memories\" or \"associative arrays\". Unlike sequences, " "which are indexed by a range of numbers, dictionaries are indexed by *keys*," " which can be any immutable type; strings and numbers can always be keys. " "Tuples can be used as keys if they contain only strings, numbers, or tuples;" " if a tuple contains any mutable object either directly or indirectly, it " "cannot be used as a key. You can't use lists as keys, since lists can be " "modified in place using index assignments, slice assignments, or methods " "like :meth:`!append` and :meth:`!extend`." msgstr "" "另一个常用的 Python 内置数据类型是 *字典* (参见 :ref:`typesmapping`)。 " "字典在其他编程语言中可能称为“联合内存”或“联合数组”。 与以连续整数为索引的序列不同，字典是以 *键* " "来索引的，键可以是任何不可变类型；字符串和数字总是可以作为键。 " "元组在其仅包含字符串、数字或元组时也可以作为键；如果一个元组直接或间接地包含了任何可变对象，则不可以用作键。 " "你不能使用列表作为键，因为列表可使用索引赋值、切片赋值或 :meth:`!append` 和 :meth:`!extend` 等方法进行原地修改。" #: ../../tutorial/datastructures.rst:506 msgid "" "It is best to think of a dictionary as a set of *key: value* pairs, with the" " requirement that the keys are unique (within one dictionary). A pair of " "braces creates an empty dictionary: ``{}``. Placing a comma-separated list " "of key:value pairs within the braces adds initial key:value pairs to the " "dictionary; this is also the way dictionaries are written on output." msgstr "" "可以把字典理解为 *键值对* 的集合，但字典的键必须是唯一的。花括号 ``{}`` " "用于创建空字典。另一种初始化字典的方式是，在花括号里输入逗号分隔的键值对，这也是字典的输出方式。" #: ../../tutorial/datastructures.rst:512 msgid "" "The main operations on a dictionary are storing a value with some key and " "extracting the value given the key. It is also possible to delete a " "key:value pair with ``del``. If you store using a key that is already in " "use, the old value associated with that key is forgotten. It is an error to" " extract a value using a non-existent key." msgstr "" "字典的主要用途是通过关键字存储、提取值。用 ``del`` " "可以删除键值对。用已存在的关键字存储值，与该关键字关联的旧值会被取代。通过不存在的键提取值，则会报错。" #: ../../tutorial/datastructures.rst:518 msgid "" "Performing ``list(d)`` on a dictionary returns a list of all the keys used " "in the dictionary, in insertion order (if you want it sorted, just use " "``sorted(d)`` instead). To check whether a single key is in the dictionary, " "use the :keyword:`in` keyword." msgstr "" "对字典执行 ``list(d)`` 操作，返回该字典中所有键的列表，按插入次序排列 (如需排序，请使用 ``sorted(d)``)。 " "检查字典里是否存在某个键，使用关键字 :keyword:`in`。" #: ../../tutorial/datastructures.rst:523 msgid "Here is a small example using a dictionary::" msgstr "以下是一些字典的简单示例：" #: ../../tutorial/datastructures.rst:525 msgid "" ">>> tel = {'jack': 4098, 'sape': 4139}\n" ">>> tel['guido'] = 4127\n" ">>> tel\n" "{'jack': 4098, 'sape': 4139, 'guido': 4127}\n" ">>> tel['jack']\n" "4098\n" ">>> del tel['sape']\n" ">>> tel['irv'] = 4127\n" ">>> tel\n" "{'jack': 4098, 'guido': 4127, 'irv': 4127}\n" ">>> list(tel)\n" "['jack', 'guido', 'irv']\n" ">>> sorted(tel)\n" "['guido', 'irv', 'jack']\n" ">>> 'guido' in tel\n" "True\n" ">>> 'jack' not in tel\n" "False" msgstr "" ">>> tel = {'jack': 4098, 'sape': 4139}\n" ">>> tel['guido'] = 4127\n" ">>> tel\n" "{'jack': 4098, 'sape': 4139, 'guido': 4127}\n" ">>> tel['jack']\n" "4098\n" ">>> del tel['sape']\n" ">>> tel['irv'] = 4127\n" ">>> tel\n" "{'jack': 4098, 'guido': 4127, 'irv': 4127}\n" ">>> list(tel)\n" "['jack', 'guido', 'irv']\n" ">>> sorted(tel)\n" "['guido', 'irv', 'jack']\n" ">>> 'guido' in tel\n" "True\n" ">>> 'jack' not in tel\n" "False" #: ../../tutorial/datastructures.rst:544 msgid "" "The :func:`dict` constructor builds dictionaries directly from sequences of " "key-value pairs::" msgstr ":func:`dict` 构造函数可以直接用键值对序列创建字典：" #: ../../tutorial/datastructures.rst:547 msgid "" ">>> dict([('sape', 4139), ('guido', 4127), ('jack', 4098)])\n" "{'sape': 4139, 'guido': 4127, 'jack': 4098}" msgstr "" ">>> dict([('sape', 4139), ('guido', 4127), ('jack', 4098)])\n" "{'sape': 4139, 'guido': 4127, 'jack': 4098}" #: ../../tutorial/datastructures.rst:550 msgid "" "In addition, dict comprehensions can be used to create dictionaries from " "arbitrary key and value expressions::" msgstr "字典推导式可以用任意键值表达式创建字典：" #: ../../tutorial/datastructures.rst:553 msgid "" ">>> {x: x**2 for x in (2, 4, 6)}\n" "{2: 4, 4: 16, 6: 36}" msgstr "" ">>> {x: x**2 for x in (2, 4, 6)}\n" "{2: 4, 4: 16, 6: 36}" #: ../../tutorial/datastructures.rst:556 msgid "" "When the keys are simple strings, it is sometimes easier to specify pairs " "using keyword arguments::" msgstr "关键字是比较简单的字符串时，直接用关键字参数指定键值对更便捷：" #: ../../tutorial/datastructures.rst:559 msgid "" |
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