{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# 字符比较\n", "\n", "{mod}`difflib` 模块包含用来计算字符序列间不同并进行处理的工具。它在比较文本方面十分有效，同时还包含了利用若干公共差异格式来生成报告的函数。\n", "\n", "示例：" ] }, { "cell_type": "code", "execution_count": 1, "metadata": {}, "outputs": [], "source": [ "text1 = \"\"\"Lorem ipsum dolor sit amet, consectetuer adipiscing\n", "elit. Integer eu lacus accumsan arcu fermentum euismod. Donec\n", "pulvinar porttitor tellus. Aliquam venenatis. Donec facilisis\n", "pharetra tortor. In nec mauris eget magna consequat\n", "convalis. Nam sed sem vitae odio pellentesque interdum. Sed\n", "consequat viverra nisl. Suspendisse arcu metus, blandit quis,\n", "rhoncus ac, pharetra eget, velit. Mauris urna. Morbi nonummy\n", "molestie orci. Praesent nisi elit, fringilla ac, suscipit non,\n", "tristique vel, mauris. Curabitur vel lorem id nisl porta\n", "adipiscing. Suspendisse eu lectus. In nunc. Duis vulputate\n", "tristique enim. Donec quis lectus a justo imperdiet tempus.\"\"\"\n", "\n", "text1_lines = text1.splitlines()\n", "\n", "text2 = \"\"\"Lorem ipsum dolor sit amet, consectetuer adipiscing\n", "elit. Integer eu lacus accumsan arcu fermentum euismod. Donec\n", "pulvinar, porttitor tellus. Aliquam venenatis. Donec facilisis\n", "pharetra tortor. In nec mauris eget magna consequat\n", "convalis. Nam cras vitae mi vitae odio pellentesque interdum. Sed\n", "consequat viverra nisl. Suspendisse arcu metus, blandit quis,\n", "rhoncus ac, pharetra eget, velit. Mauris urna. Morbi nonummy\n", "molestie orci. Praesent nisi elit, fringilla ac, suscipit non,\n", "tristique vel, mauris. Curabitur vel lorem id nisl porta\n", "adipiscing. Duis vulputate tristique enim. Donec quis lectus a\n", "justo imperdiet tempus. Suspendisse eu lectus. In nunc.\"\"\"\n", "\n", "text2_lines = text2.splitlines()" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "## 比较文本体\n", "\n", "{class}`difflib.Differ` 类适用于文本行序列并产生人类可读的 增量，或更改指令，包括各行内的差异。{class}`difflib.Differ` 生成的默认输出类似于 Unix 下的 diff 命令行工具。它包括来自两个列表的原始输入值（包括公共值）和标记数据，以指示进行了哪些更改。\n", "\n", "- 以 `-` 为前缀的行在第一个序列中，但不在第二个序列中。\n", "- 以 `+` 为前缀的行在第二个序列中，但不在第一个序列中。\n", "- 如果某行之间的版本之间存在增量差异，则使用前缀为 `?` 的额外行来突出显示新版本中的更改。\n", "- 如果一条线没有改变，则在左列上打印一个额外的空白区域，使其与可能存在差异的另一个输出对齐。\n", "- 在将文本传递给 {meth}`~difflib.Differ.compare` 之前将文本分解为一系列单独的行会生成比传入大字符串更可读的输出。\n" ] }, { "cell_type": "code", "execution_count": 2, "metadata": {}, "outputs": [ { "data": { "text/html": [ "
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       "+ pulvinar, porttitor tellus. Aliquam venenatis. Donec facilisis\n",
       "?         +\n",
       "\n",
       "- pharetra tortor.  In nec mauris eget magna consequat\n",
       "?                 -\n",
       "\n",
       "+ pharetra tortor. In nec mauris eget magna consequat\n",
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       "?                 - --\n",
       "\n",
       "+ convalis. Nam cras vitae mi vitae odio pellentesque interdum. Sed\n",
       "?               +++ +++++   +\n",
       "\n",
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       "- adipiscing. Suspendisse eu lectus. In nunc. Duis vulputate\n",
       "- tristique enim. Donec quis lectus a justo imperdiet tempus.\n",
       "+ adipiscing. Duis vulputate tristique enim. Donec quis lectus a\n",
       "+ justo imperdiet tempus.  Suspendisse eu lectus. In nunc.\n",
       "
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Integer eu lacus accumsan arcu fermentum euismod. Donec\n", "- pulvinar porttitor tellus. Aliquam venenatis. Donec facilisis\n", "+ pulvinar, porttitor tellus. Aliquam venenatis. Donec facilisis\n", "? +\n", "\n", "- pharetra tortor. In nec mauris eget magna consequat\n", "? -\n", "\n", "+ pharetra tortor. In nec mauris eget magna consequat\n", "- convalis. Nam sed sem vitae odio pellentesque interdum. Sed\n", "? - --\n", "\n", "+ convalis. Nam cras vitae mi vitae odio pellentesque interdum. Sed\n", "? +++ +++++ +\n", "\n", " consequat viverra nisl. Suspendisse arcu metus, blandit quis,\n", " rhoncus ac, pharetra eget, velit. Mauris urna. Morbi nonummy\n", " molestie orci. Praesent nisi elit, fringilla ac, suscipit non,\n", " tristique vel, mauris. Curabitur vel lorem id nisl porta\n", "- adipiscing. Suspendisse eu lectus. In nunc. Duis vulputate\n", "- tristique enim. Donec quis lectus a justo imperdiet tempus.\n", "+ adipiscing. Duis vulputate tristique enim. Donec quis lectus a\n", "+ justo imperdiet tempus. Suspendisse eu lectus. In nunc." ] }, "execution_count": 2, "metadata": {}, "output_type": "execute_result" } ], "source": [ "from IPython.display import Code\n", "import difflib\n", "\n", "d = difflib.Differ()\n", "diff = d.compare(text1_lines, text2_lines)\n", "Code('\\n'.join(diff), language=\"python\")" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "样本数据中两个文本段的开头是相同的，因此第一行打印时没有任何额外的注释。\n", "\n", "数据的第三行已更改为在修改后包含逗号的文本。 该行的两个版本都打印出来，第 5 行的额外信息显示了修改文本的列，包括添加了 `,` 字符的事实。输出的下几行显示删除了额外的空间。接下来，进行了更复杂的更改，替换了短语中的多个单词。\n", "\n", "段落中的最后一句被大量改变，因此通过删除旧版本并添加新版本来表示差异。\n", "\n", "```{tip}\n", "{func}`difflib.ndiff` 函数产生基本相同的输出。该处理专门用于处理文本数据并消除输入中的 “噪声”。\n", "```\n", "\n", "虽然 {class}`difflib.Differ` 类展示了所有的输入行，{func}`difflib.unified_diff` 仅包括修改过的行和一些上下文。" ] }, { "cell_type": "code", "execution_count": 3, "metadata": {}, "outputs": [ { "data": { "text/html": [ "
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       "-pharetra tortor.  In nec mauris eget magna consequat\n",
       "-convalis. Nam sed sem vitae odio pellentesque interdum. Sed\n",
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       "+pharetra tortor. In nec mauris eget magna consequat\n",
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       " rhoncus ac, pharetra eget, velit. Mauris urna. Morbi nonummy\n",
       " molestie orci. Praesent nisi elit, fringilla ac, suscipit non,\n",
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       "-adipiscing. Suspendisse eu lectus. In nunc. Duis vulputate\n",
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\n" ], "text/latex": [ "\\begin{Verbatim}[commandchars=\\\\\\{\\}]\n", "\\PY{o}{\\PYZhy{}}\\PY{o}{\\PYZhy{}}\\PY{o}{\\PYZhy{}} \n", "\\PY{o}{+}\\PY{o}{+}\\PY{o}{+} \n", "\\PY{o}{@}\\PY{o}{@} \\PY{o}{\\PYZhy{}}\\PY{l+m+mi}{1}\\PY{p}{,}\\PY{l+m+mi}{11} \\PY{o}{+}\\PY{l+m+mi}{1}\\PY{p}{,}\\PY{l+m+mi}{11} \\PY{o}{@}\\PY{o}{@}\n", " \\PY{n}{Lorem} \\PY{n}{ipsum} \\PY{n}{dolor} \\PY{n}{sit} \\PY{n}{amet}\\PY{p}{,} \\PY{n}{consectetuer} \\PY{n}{adipiscing}\n", " \\PY{n}{elit}\\PY{o}{.} \\PY{n}{Integer} \\PY{n}{eu} \\PY{n}{lacus} \\PY{n}{accumsan} \\PY{n}{arcu} \\PY{n}{fermentum} \\PY{n}{euismod}\\PY{o}{.} \\PY{n}{Donec}\n", "\\PY{o}{\\PYZhy{}}\\PY{n}{pulvinar} \\PY{n}{porttitor} \\PY{n}{tellus}\\PY{o}{.} \\PY{n}{Aliquam} \\PY{n}{venenatis}\\PY{o}{.} \\PY{n}{Donec} \\PY{n}{facilisis}\n", "\\PY{o}{\\PYZhy{}}\\PY{n}{pharetra} \\PY{n}{tortor}\\PY{o}{.} \\PY{n}{In} \\PY{n}{nec} \\PY{n}{mauris} \\PY{n}{eget} \\PY{n}{magna} \\PY{n}{consequat}\n", "\\PY{o}{\\PYZhy{}}\\PY{n}{convalis}\\PY{o}{.} \\PY{n}{Nam} \\PY{n}{sed} \\PY{n}{sem} \\PY{n}{vitae} \\PY{n}{odio} \\PY{n}{pellentesque} \\PY{n}{interdum}\\PY{o}{.} \\PY{n}{Sed}\n", "\\PY{o}{+}\\PY{n}{pulvinar}\\PY{p}{,} \\PY{n}{porttitor} \\PY{n}{tellus}\\PY{o}{.} \\PY{n}{Aliquam} \\PY{n}{venenatis}\\PY{o}{.} \\PY{n}{Donec} \\PY{n}{facilisis}\n", "\\PY{o}{+}\\PY{n}{pharetra} \\PY{n}{tortor}\\PY{o}{.} \\PY{n}{In} \\PY{n}{nec} \\PY{n}{mauris} \\PY{n}{eget} \\PY{n}{magna} \\PY{n}{consequat}\n", "\\PY{o}{+}\\PY{n}{convalis}\\PY{o}{.} \\PY{n}{Nam} \\PY{n}{cras} \\PY{n}{vitae} \\PY{n}{mi} \\PY{n}{vitae} \\PY{n}{odio} \\PY{n}{pellentesque} \\PY{n}{interdum}\\PY{o}{.} \\PY{n}{Sed}\n", " \\PY{n}{consequat} \\PY{n}{viverra} \\PY{n}{nisl}\\PY{o}{.} \\PY{n}{Suspendisse} \\PY{n}{arcu} \\PY{n}{metus}\\PY{p}{,} \\PY{n}{blandit} \\PY{n}{quis}\\PY{p}{,}\n", " \\PY{n}{rhoncus} \\PY{n}{ac}\\PY{p}{,} \\PY{n}{pharetra} \\PY{n}{eget}\\PY{p}{,} \\PY{n}{velit}\\PY{o}{.} \\PY{n}{Mauris} \\PY{n}{urna}\\PY{o}{.} \\PY{n}{Morbi} \\PY{n}{nonummy}\n", " \\PY{n}{molestie} \\PY{n}{orci}\\PY{o}{.} \\PY{n}{Praesent} \\PY{n}{nisi} \\PY{n}{elit}\\PY{p}{,} \\PY{n}{fringilla} \\PY{n}{ac}\\PY{p}{,} \\PY{n}{suscipit} \\PY{n}{non}\\PY{p}{,}\n", " \\PY{n}{tristique} \\PY{n}{vel}\\PY{p}{,} \\PY{n}{mauris}\\PY{o}{.} \\PY{n}{Curabitur} \\PY{n}{vel} \\PY{n}{lorem} \\PY{n+nb}{id} \\PY{n}{nisl} \\PY{n}{porta}\n", "\\PY{o}{\\PYZhy{}}\\PY{n}{adipiscing}\\PY{o}{.} \\PY{n}{Suspendisse} \\PY{n}{eu} \\PY{n}{lectus}\\PY{o}{.} \\PY{n}{In} \\PY{n}{nunc}\\PY{o}{.} \\PY{n}{Duis} \\PY{n}{vulputate}\n", "\\PY{o}{\\PYZhy{}}\\PY{n}{tristique} \\PY{n}{enim}\\PY{o}{.} \\PY{n}{Donec} \\PY{n}{quis} \\PY{n}{lectus} \\PY{n}{a} \\PY{n}{justo} \\PY{n}{imperdiet} \\PY{n}{tempus}\\PY{o}{.}\n", "\\PY{o}{+}\\PY{n}{adipiscing}\\PY{o}{.} \\PY{n}{Duis} \\PY{n}{vulputate} \\PY{n}{tristique} \\PY{n}{enim}\\PY{o}{.} \\PY{n}{Donec} \\PY{n}{quis} \\PY{n}{lectus} \\PY{n}{a}\n", "\\PY{o}{+}\\PY{n}{justo} \\PY{n}{imperdiet} \\PY{n}{tempus}\\PY{o}{.} \\PY{n}{Suspendisse} \\PY{n}{eu} \\PY{n}{lectus}\\PY{o}{.} \\PY{n}{In} \\PY{n}{nunc}\\PY{o}{.}\n", "\\end{Verbatim}\n" ], "text/plain": [ "--- \n", "+++ \n", "@@ -1,11 +1,11 @@\n", " Lorem ipsum dolor sit amet, consectetuer adipiscing\n", " elit. Integer eu lacus accumsan arcu fermentum euismod. Donec\n", "-pulvinar porttitor tellus. Aliquam venenatis. Donec facilisis\n", "-pharetra tortor. In nec mauris eget magna consequat\n", "-convalis. Nam sed sem vitae odio pellentesque interdum. Sed\n", "+pulvinar, porttitor tellus. Aliquam venenatis. Donec facilisis\n", "+pharetra tortor. In nec mauris eget magna consequat\n", "+convalis. Nam cras vitae mi vitae odio pellentesque interdum. Sed\n", " consequat viverra nisl. Suspendisse arcu metus, blandit quis,\n", " rhoncus ac, pharetra eget, velit. Mauris urna. Morbi nonummy\n", " molestie orci. Praesent nisi elit, fringilla ac, suscipit non,\n", " tristique vel, mauris. Curabitur vel lorem id nisl porta\n", "-adipiscing. Suspendisse eu lectus. In nunc. Duis vulputate\n", "-tristique enim. Donec quis lectus a justo imperdiet tempus.\n", "+adipiscing. Duis vulputate tristique enim. Donec quis lectus a\n", "+justo imperdiet tempus. Suspendisse eu lectus. In nunc." ] }, "execution_count": 3, "metadata": {}, "output_type": "execute_result" } ], "source": [ "diff = difflib.unified_diff(\n", " text1_lines,\n", " text2_lines,\n", " lineterm='',\n", ")\n", "Code('\\n'.join(diff), language=\"python\")" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "`lineterm` 参数用于告诉 {func}`difflib.unified_diff` 跳过追加新行到它返回的控制行，因为输入行不包含它们。打印时，新行将添加到所有行。对于许多流行的版本控制工具的用户来说，输出看起来应该很熟悉。\n", "\n", "```{tip}\n", "使用 {func}`difflib.context_diff` 产生类似的可读输出。\n", "```" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## 垃圾数据\n", "\n", "生成差异序列的所有函数都接受参数，以指示应忽略哪些行以及应忽略行中的哪些字符。例如，这些参数可用于跳过一个文件的两个版本中的标记或空白变化。" ] }, { "cell_type": "code", "execution_count": 4, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "A = ' abcd'\n", "B = 'abcd abcd'\n", "\n", "Without junk detection:\n", " a = 0\n", " b = 4\n", " size = 5\n", " A[a:a+size] = ' abcd'\n", " B[b:b+size] = ' abcd'\n", "\n", "Treat spaces as junk:\n", " a = 1\n", " b = 0\n", " size = 4\n", " A[a:a+size] = 'abcd'\n", " B[b:b+size] = 'abcd'\n" ] } ], "source": [ "from difflib import SequenceMatcher\n", "\n", "def show_results(match):\n", " print(' a = {}'.format(match.a))\n", " print(' b = {}'.format(match.b))\n", " print(' size = {}'.format(match.size))\n", " i, j, k = match\n", " print(' A[a:a+size] = {!r}'.format(A[i:i + k]))\n", " print(' B[b:b+size] = {!r}'.format(B[j:j + k]))\n", "\n", "A = \" abcd\"\n", "B = \"abcd abcd\"\n", "\n", "print('A = {!r}'.format(A))\n", "print('B = {!r}'.format(B))\n", "\n", "print('\\nWithout junk detection:')\n", "s1 = SequenceMatcher(None, A, B)\n", "match1 = s1.find_longest_match(0, len(A), 0, len(B))\n", "show_results(match1)\n", "\n", "print('\\nTreat spaces as junk:')\n", "s2 = SequenceMatcher(lambda x: x == \" \", A, B)\n", "match2 = s2.find_longest_match(0, len(A), 0, len(B))\n", "show_results(match2)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## 输出 HTML" ] }, { "cell_type": "code", "execution_count": 5, "metadata": {}, "outputs": [], "source": [ "from IPython.display import HTML\n", "from difflib import HtmlDiff" ] }, { "cell_type": "code", "execution_count": 6, "metadata": {}, "outputs": [ { "data": { "text/html": [ "\n", " \n", " \n", " \n", " \n", " \n", " \n", " \n", " \n", " \n", " \n", "
n1 abcdn1 abqcd
2abcd abcd
2abd3abd
t3 abqcdt
" ], "text/plain": [ "" ] }, "execution_count": 6, "metadata": {}, "output_type": "execute_result" } ], "source": [ "dis_tool = HtmlDiff()\n", "A = \" abcd\"\n", "A1 = \"abd\"\n", "A2 = \" abqcd\"\n", "A3 = \"abcd abcd\"\n", "HTML(dis_tool.make_table([A, A1, A2], [A2, A3, A1]))" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "## 比较任意类型\n", "\n", "{class}`difflib.SequenceMatcher` 类比较任意类型的两个序列，只要值是可散列的。它使用一种算法来识别序列中最长的连续匹配块，消除了对真实数据没用的 “垃圾” 值。\n", "\n", "函数 {meth}`~difflib.SequenceMatcher.get_opcodes` 返回指令列表，用于修改第一个序列以使其与第二个序列匹配。指令被编码为五元素元组，包括一个字符串指令（「操作码」，见下表）和两对开始和停止索引到序列中（表示为 `i1`，`i2`，`j1`，和 `j2`）。\n", "\n", "操作码|定义\n", ":-|:-\n", "`'replace'`|将 `a[i1:i2]` 替换为 `b[j1:j2]`\n", "`'delete'`|完全移除 `a[i1:i2]`\n", "`'insert'`|将 `b[j1:j2]` 插入到 `a[i1:i1]`\n", "`'equal'`|子序列完全相等" ] }, { "cell_type": "code", "execution_count": 7, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Initial data:\n", "s1 = [1, 2, 3, 5, 6, 4]\n", "s2 = [2, 3, 5, 4, 6, 1]\n", "s1 == s2: False\n", "\n", "Replace [4] from s1[5:6] with [1] from s2[5:6]\n", " before = [1, 2, 3, 5, 6, 4]\n", " after = [1, 2, 3, 5, 6, 1] \n", "\n", "s1[4:5] and s2[4:5] are the same\n", " after = [1, 2, 3, 5, 6, 1] \n", "\n", "Insert [4] from s2[3:4] into s1 at 4\n", " before = [1, 2, 3, 5, 6, 1]\n", " after = [1, 2, 3, 5, 4, 6, 1] \n", "\n", "s1[1:4] and s2[0:3] are the same\n", " after = [1, 2, 3, 5, 4, 6, 1] \n", "\n", "Remove [1] from positions [0:1]\n", " before = [1, 2, 3, 5, 4, 6, 1]\n", " after = [2, 3, 5, 4, 6, 1] \n", "\n", "s1 == s2: True\n" ] } ], "source": [ "import difflib\n", "\n", "s1 = [1, 2, 3, 5, 6, 4]\n", "s2 = [2, 3, 5, 4, 6, 1]\n", "\n", "print('Initial data:')\n", "print('s1 =', s1)\n", "print('s2 =', s2)\n", "print('s1 == s2:', s1 == s2)\n", "print()\n", "\n", "matcher = difflib.SequenceMatcher(None, s1, s2)\n", "for tag, i1, i2, j1, j2 in reversed(matcher.get_opcodes()):\n", "\n", " if tag == 'delete':\n", " print('Remove {} from positions [{}:{}]'.format(\n", " s1[i1:i2], i1, i2))\n", " print(' before =', s1)\n", " del s1[i1:i2]\n", "\n", " elif tag == 'equal':\n", " print('s1[{}:{}] and s2[{}:{}] are the same'.format(\n", " i1, i2, j1, j2))\n", "\n", " elif tag == 'insert':\n", " print('Insert {} from s2[{}:{}] into s1 at {}'.format(\n", " s2[j1:j2], j1, j2, i1))\n", " print(' before =', s1)\n", " s1[i1:i2] = s2[j1:j2]\n", "\n", " elif tag == 'replace':\n", " print(('Replace {} from s1[{}:{}] '\n", " 'with {} from s2[{}:{}]').format(\n", " s1[i1:i2], i1, i2, s2[j1:j2], j1, j2))\n", " print(' before =', s1)\n", " s1[i1:i2] = s2[j1:j2]\n", "\n", " print(' after =', s1, '\\n')\n", "\n", "print('s1 == s2:', s1 == s2)" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "此示例比较两个整数列表，并使用 {meth}`~difflib.SequenceMatcher.get_opcodes` 派生将原始列表转换为较新版本的指令。以相反的顺序修改，以便在添加和删除项目后列表索引保持准确。\n", "\n", "```{note}\n", "{class}`difflib.SequenceMatcher` 适用于自定义类以及内置类型，只要它们是可散列的。\n", "```" ] } ], "metadata": { "kernelspec": { "display_name": "py310", "language": "python", "name": "python3" }, "language_info": { "codemirror_mode": { "name": "ipython", "version": 3 }, "file_extension": ".py", "mimetype": "text/x-python", "name": "python", "nbconvert_exporter": "python", "pygments_lexer": "ipython3", "version": "3.10.8" }, "orig_nbformat": 4, "vscode": { "interpreter": { "hash": "34e95b0948f576614c7863cc780d83f61f9551597d4ec05ab5fbb4cfe73deb20" } } }, "nbformat": 4, "nbformat_minor": 2 }