Example syntax for nested list comprehensions

nested_list_comps.ipynb

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    "<h1>Table of Contents<span class=\"tocSkip\"></span></h1>\n",
    "<div class=\"toc\"><ul class=\"toc-item\"><li><span><a href=\"#Example-syntax-for-nested-list-comprehensions\" data-toc-modified-id=\"Example-syntax-for-nested-list-comprehensions-1\">Example syntax for nested list comprehensions</a></span></li><li><span><a href=\"#Nested-data\" data-toc-modified-id=\"Nested-data-2\">Nested data</a></span></li><li><span><a href=\"#List-by-list-processing-with-list-comprehension\" data-toc-modified-id=\"List-by-list-processing-with-list-comprehension-3\">List-by-list processing with list comprehension</a></span></li><li><span><a href=\"#Item-by-item-processing-with-nested-list-comprehension\" data-toc-modified-id=\"Item-by-item-processing-with-nested-list-comprehension-4\">Item-by-item processing with nested list comprehension</a></span></li><li><span><a href=\"#Further-Study\" data-toc-modified-id=\"Further-Study-5\">Further Study</a></span></li></ul></div>"
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   "source": [
    "Example syntax for nested list comprehensions\n",
    "-----"
   ]
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   "source": [
    "reset -fs"
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    "Nested data\n",
    "----"
   ]
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     "data": {
      "text/plain": [
       "[['a', 'b'], ['c', 'd'], ['e', 'f']]"
      ]
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     "execution_count": 18,
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   "source": [
    "letters = ['a b'.split(),\n",
    "            'c d'.split(),\n",
    "            'e f'.split()]\n",
    "letters"
   ]
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    "List-by-list processing with list comprehension\n",
    "----"
   ]
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       "[['a', 'b'], ['c', 'd'], ['e', 'f']]"
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    "[row for row in letters]"
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    "[row.count('d') for row in letters]"
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   "source": [
    "Item-by-item processing with nested list comprehension\n",
    "----"
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     "execution_count": 21,
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    "[[item for item in row] for row in letters]"
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     "data": {
      "text/plain": [
       "[['A', 'B'], ['C', 'D'], ['E', 'F']]"
      ]
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    "[[item.title() for item in row] for row in letters]"
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   "source": [
    "Further Study\n",
    "------\n",
    "\n",
    "The official documentation is [here](https://docs.python.org/3/reference/expressions.html#list-displays).\n",
    "\n",
    "Personally, I find it hard to understand"
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