{"id":12024,"date":"2022-09-29T09:12:19","date_gmt":"2022-09-29T03:42:19","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-is-there-a-more-efficient-way-to-find-index-of-an-element-without-using-list-built-in-functions\/"},"modified":"2022-09-29T09:12:19","modified_gmt":"2022-09-29T03:42:19","slug":"solved-is-there-a-more-efficient-way-to-find-index-of-an-element-without-using-list-built-in-functions","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-is-there-a-more-efficient-way-to-find-index-of-an-element-without-using-list-built-in-functions\/","title":{"rendered":"[Solved] Is there a more efficient way to find index of an element without using list built-in functions?"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-71182817\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"71182817\" data-parentid=\"71182766\" data-score=\"2\" data-position-on-page=\"1\" data-highest-scored=\"1\" data-question-has-accepted-highest-score=\"1\" itemprop=\"acceptedAnswer\" itemscope itemtype=\"https:\/\/schema.org\/Answer\">\n<div class=\"post-layout\">\n<div class=\"votecell post-layout--left\"><\/div>\n<div class=\"answercell post-layout--right\">\n<div class=\"s-prose js-post-body\" itemprop=\"text\">\n<h2>use <a rel=\"nofollow noopener\" target=\"_blank\" href=\"https:\/\/www.geeksforgeeks.org\/python-list-comprehension\/\">list comprehension<\/a> in python<\/h2>\n<pre><code>l = [3, 11, 4, 9, 1, 23, 5, 11]\nindexes = [index for index in range(len(l)) if l[index] == 11]\n<\/code><\/pre>\n<p>output:<\/p>\n<pre><code>[1, 7]\n<\/code><\/pre>\n<h2>use <code>numpy<\/code> for finding the matching indices.<\/h2>\n<pre><code>import numpy as np\n\nl = [3, 11, 4, 9, 1, 23, 5, 11]\nnp_array = np.array(l)\nitem_index = np.where(np_array == 11)\nprint (item_index)\n<\/code><\/pre>\n<h2><a rel=\"nofollow noopener\" target=\"_blank\" href=\"https:\/\/numpy.org\/\">Numpy<\/a> is efficient:<\/h2>\n<pre><code>import random\nimport time\n\nimport numpy as np\n\nlimit = 10 ** 7\nl = [None] * limit\nfor i in range(limit):\n    l[i] = random.randint(0, 1000000)\n\nstart = time.time()\nnp_array = np.array(l)\nitem_index = np.where(np_array == 11)\nprint('time taken by numpy', time.time() - start)\n\nstart = time.time()\nfor index, value in enumerate(l):\n    if (value == 11):\n        pass\nprint('time taken by enumerate',time.time() - start)\n<\/code><\/pre>\n<p>Output:<\/p>\n<pre><code>time taken by numpy 0.9375550746917725\ntime taken by enumerate 1.4508612155914307\n<\/code><\/pre>\n<h2><a rel=\"nofollow noopener\" target=\"_blank\" href=\"https:\/\/docs.python.org\/3\/library\/timeit.html\">timeit<\/a><\/h2>\n<pre><code>import random\nimport sys\nimport time\nfrom multiprocessing import Process\nfrom threading import Thread\n\nimport numpy as np\n\nstart = time.time()\nlimit = (10 ** 4)\nl = [None] * limit\nfor i in range(limit):\n    l[i] = random.randint(0, 1000000)\n\n\ndef testNumpy():\n    np_array = np.array(l)\n    for i in range(1000):\n        value = random.randint(0, 1000000)\n        item_index = np.where(np_array == value)\n\n\ndef testEnumerate():\n    for i in range(1000):\n        randValue = random.randint(0, 1000000)\n        for index, value in enumerate(l):\n            if (value == randValue):\n                pass\n\n\ndef _testNumpy(repeat):\n    import timeit\n    s = \"\"\"\\\ntestNumpy()\n    \"\"\"\n    print(timeit.timeit(stmt=s, setup=\"from __main__ import testNumpy\", number=repeat, globals=globals()),\n          end=\":numpy\\n\")\n\n\ndef _testEnumerate(repeat):\n    import timeit\n    s = \"\"\"\\\ntestEnumerate()\n        \"\"\"\n    print(timeit.timeit(stmt=s, setup=\"from __main__ import testEnumerate\", number=repeat, globals=globals()),\n          end=':enumerate\\n')\n\n\nif __name__ == \"__main__\":\n    repeat = 10\n    processes = [Process(target=_testNumpy, args=(repeat,)), Process(target=_testEnumerate, args=(repeat,))]\n    for process in processes:\n        process.start()\n\n    for process in processes:\n        process.join()\n<\/code><\/pre>\n<p>Output:<\/p>\n<pre><code>0.2232685430001311:numpy\n8.573617108999997:enumerate\n<\/code><\/pre>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">7<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved Is there a more efficient way to find index of an element without using list built-in functions? <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] use list comprehension in python l = [3, 11, 4, 9, 1, 23, 5, 11] indexes = [index for index in range(len(l)) if l[index] == 11] output: [1, 7] use numpy for finding the matching indices. import numpy as np l = [3, 11, 4, 9, 1, 23, 5, 11] np_array = np.array(l) item_index &#8230; <a title=\"[Solved] Is there a more efficient way to find index of an element without using list built-in functions?\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-is-there-a-more-efficient-way-to-find-index-of-an-element-without-using-list-built-in-functions\/\" aria-label=\"More on [Solved] Is there a more efficient way to find index of an element without using list built-in functions?\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[821,540,325,349],"class_list":["post-12024","post","type-post","status-publish","format-standard","hentry","category-solved","tag-indexing","tag-list","tag-performance","tag-python"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] Is there a more efficient way to find index of an element without using list built-in functions? 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