{"id":7254,"date":"2020-05-20T15:33:05","date_gmt":"2020-05-20T10:03:05","guid":{"rendered":"https:\/\/pynative.com\/?p=7254"},"modified":"2021-06-16T17:58:24","modified_gmt":"2021-06-16T12:28:24","slug":"python-weighted-random-choices-with-probability","status":"publish","type":"post","link":"https:\/\/pynative.com\/python-weighted-random-choices-with-probability\/","title":{"rendered":"Python weighted random choices to choose from the list with different probability"},"content":{"rendered":"\n<p>This lesson demonstrates ways to choose single or multiple elements from the <a href=\"https:\/\/pynative.com\/python-lists\/\">list<\/a> randomly with a different probability. Use the <code>random.choices()<\/code> function to get the weighted random samples in Python.<\/p>\n\n\n\n<div class=\"wp-block-columns has-background is-layout-flex wp-container-core-columns-is-layout-1 wp-block-columns-is-layout-flex\" style=\"background-color:#c0e5fc\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<p><strong>Also, See<\/strong>:<\/p>\n\n\n\n<ul><li><a href=\"https:\/\/pynative.com\/python-random-number-generation-exercise-questions-and-challenge\/\">Python random data generation Exercise<\/a><\/li><li><a href=\"https:\/\/pynative.com\/python-random-data-generation-quiz\/\">Python random data generation Quiz<\/a><\/li><\/ul>\n<\/div>\n<\/div>\n\n\n\n<p>Let&#8217;s take the following example for a better understanding of the requirement.<\/p>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code1\"  class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-1\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">import<\/span> random\n\nsampleList = &#91;<span class=\"hljs-number\">10<\/span>, <span class=\"hljs-number\">20<\/span>, <span class=\"hljs-number\">30<\/span>, <span class=\"hljs-number\">40<\/span>]\nx = random.choice(sampleList)\nprint(x)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-1\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code1', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><button class=\"hljs-run-button\" onclick=\"run_code('code1');\"><i class=\"far fa-play-circle\" aria-hidden=\"true\"><\/i> Run<\/button><\/div>\n\n\n<p>If you execute the <a href=\"https:\/\/pynative.com\/python-random-choice\/\">random.choice()<\/a> in the above code, it will give you 10, 20, 30, or 40 with equal probability. But what if you want to pick the element from the list with a different probability. For example, choose a list of items from any sequence in such a way that each element has a different probability of being selected.<\/p>\n\n\n\n<p>In other words, choose 4 elements from the list randomly with different probabilities. For example:<\/p>\n\n\n\n<ul><li>Choose 10 \u2013 10% of the time<\/li><li>Choose 20 \u2013 25% of the time<\/li><li>Choose 30 \u2013 50% of the time<\/li><li>Choose 40 \u2013 15% of the time<\/li><\/ul>\n\n\n\n<p><strong>There are 2 ways to make weighted random choices in Python<\/strong><\/p>\n\n\n\n<ul><li>If you are using Python 3.6 or above then use the <code>random.choice<span style=\"color: #ff6600;\">s<\/span>()<\/code><\/li><li>Else, use a <code>numpy.random.choice()<\/code><\/li><\/ul>\n\n\n\n<p>We will see how to use both one by one.<\/p>\n\n\n\n<div class=\"wp-block-yoast-seo-table-of-contents yoast-table-of-contents\"><h2>Table of contents<\/h2><ul><li><a href=\"#h-random-choices\" data-level=\"2\">random.choices()<\/a><ul><li><a href=\"#h-syntax\" data-level=\"3\">Syntax<\/a><\/li><\/ul><\/li><li><a href=\"#h-relative-weights-to-choose-elements-from-the-list-with-different-probability\" data-level=\"2\">Relative weights to choose elements from the list with different probability<\/a><\/li><li><a href=\"#h-cumulative-weights-to-choose-items-from-the-list-with-different-probability\" data-level=\"2\">Cumulative weights to choose items from the list with different probability<\/a><ul><li><a href=\"#h-choose-a-single-element-form-list-with-different-probability\" data-level=\"3\">Choose a single element form list with different probability<\/a><\/li><\/ul><\/li><li><a href=\"#h-probability-of-getting-6-or-more-heads-from-10-spins\" data-level=\"2\">Probability of getting 6 or more heads from 10 spins<\/a><\/li><li><a href=\"#h-generate-weighted-random-numbers\" data-level=\"2\">Generate weighted random numbers<\/a><\/li><li><a href=\"#h-points-to-remember-before-implementing-weighted-random-choices\" data-level=\"2\">Points to remember before implementing weighted random choices<\/a><\/li><li><a href=\"#h-numpy-s-random-choice-to-choose-elements-from-the-list-with-different-probability\" data-level=\"2\">Numpy&#8217;s random.choice() to choose elements from the list with different probability<\/a><\/li><li><a href=\"#h-next-steps\" data-level=\"2\">Next Steps<\/a><\/li><\/ul><\/div>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-random-choices\"><strong>random.choices()<\/strong><\/h2>\n\n\n\n<p>Python 3.6 introduced a new function <code><a href=\"https:\/\/docs.python.org\/3\/library\/random.html#random.choices\" target=\"_blank\" rel=\"noreferrer noopener\">random.choices()<\/a><\/code> in the <a href=\"https:\/\/pynative.com\/python\/random\/\">random module<\/a>. By using the <code>choices()<\/code> function, we can make a weighted random choice with replacement. You can also call it a weighted random sample with replacement. <\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"h-syntax\"><strong>Syntax<\/strong><\/h3>\n\n\n\n<p>Let&#8217;s have a look at the syntax of this function.<\/p>\n\n\n<pre id=\"syntax\" class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-2\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">random.choices(population,\u00a0weights=<span class=\"hljs-literal\">None<\/span>,\u00a0*,\u00a0cum_weights=<span class=\"hljs-literal\">None<\/span>,\u00a0k=<span class=\"hljs-number\">1<\/span>)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-2\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>It returns a <code>k<\/code> sized list of elements chosen from the <code>population<\/code> with replacement.<\/p>\n\n\n\n<p><strong>Parameters<\/strong><\/p>\n\n\n\n<ul><li><code>population<\/code>: It is is sequence or data structure from which you want to choose data.<\/li><li><code>weights<\/code> or <code>cum_weights<\/code>: Define the selection probability for each element.<\/li><li><code>weights<\/code>: If a <code>weights<\/code> sequence is specified, random selections are made according to the relative weights.<\/li><li><code>cum_weights<\/code>: Alternatively, if a cum_weights sequence is given, the random selections are made according to the cumulative weights.<\/li><li><code>k<\/code>: The number of samples you want from a <code>population<\/code>.<\/li><\/ul>\n\n\n\n<p><strong>Note<\/strong>: You cannot specify both <code>weights<\/code> and <code>cum_weights<\/code> at the same time.<\/p>\n\n\n\n<p>As mentioned above we can define weights sequence using the following two ways<\/p>\n\n\n\n<ol><li><strong>Relative weights<\/strong><\/li><li><strong>Cumulative weights<\/strong><\/li><\/ol>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1051\" height=\"403\" src=\"https:\/\/pynative.com\/wp-content\/uploads\/2020\/05\/python-weighted-random-choices-with-different-probability.jpg\" alt=\"Python weighted random choices to choose from the list with different probability\" class=\"wp-image-7256\" srcset=\"https:\/\/pynative.com\/wp-content\/uploads\/2020\/05\/python-weighted-random-choices-with-different-probability.jpg 1051w, https:\/\/pynative.com\/wp-content\/uploads\/2020\/05\/python-weighted-random-choices-with-different-probability-300x115.jpg 300w, https:\/\/pynative.com\/wp-content\/uploads\/2020\/05\/python-weighted-random-choices-with-different-probability-1024x393.jpg 1024w, https:\/\/pynative.com\/wp-content\/uploads\/2020\/05\/python-weighted-random-choices-with-different-probability-768x294.jpg 768w\" sizes=\"(max-width: 1051px) 100vw, 1051px\" \/><figcaption>Python weighted random choices to choose from the list with different probability<\/figcaption><\/figure><\/div>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-relative-weights-to-choose-elements-from-the-list-with-different-probability\"><strong>Relative weights to choose elements from the list with different probability<\/strong><\/h2>\n\n\n\n<p>First, define the probability for each element. If you specified the probability using the relative weight, the selections are made according to the relative weights. You can set relative weights using the <code>weight<\/code> parameter.<\/p>\n\n\n\n<p><strong>Example<\/strong>: <strong>Choose 5 elements from the list with different probability<\/strong><\/p>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code2\"  class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-3\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">import<\/span> random\n\nnumberList = &#91;<span class=\"hljs-number\">111<\/span>, <span class=\"hljs-number\">222<\/span>, <span class=\"hljs-number\">333<\/span>, <span class=\"hljs-number\">444<\/span>, <span class=\"hljs-number\">555<\/span>]\nprint(random.choices(numberList, weights=(<span class=\"hljs-number\">10<\/span>, <span class=\"hljs-number\">20<\/span>, <span class=\"hljs-number\">30<\/span>, <span class=\"hljs-number\">40<\/span>, <span class=\"hljs-number\">50<\/span>), k=<span class=\"hljs-number\">5<\/span>))\n<span class=\"hljs-comment\"># Output &#91;555, 222, 555, 222, 555]<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-3\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code2', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><button class=\"hljs-run-button\" onclick=\"run_code('code2');\"><i class=\"far fa-play-circle\" aria-hidden=\"true\"><\/i> Run<\/button><\/div>\n\n\n<p><strong>Note<\/strong>:<\/p>\n\n\n\n<ul><li>As you can see in the output, we received an item &#8216;<em><strong>555<\/strong>&#8216;<\/em>&nbsp;three times because we assigned the highest weight to it. So it has the highest probability to be selected<\/li><li>Weights sum is not 100 because they&#8217;re relative weights, not percentages.<\/li><\/ul>\n\n\n\n<p>The following rule determines the weighted probability of selecting each element.<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-4\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">Probability = element_weight\/ sum of all weights<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-4\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In the above example, the probability of occurring each element is determined is as follows<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">The total weight is 10+20+30+40+50 = 150\nList is [111, 222, 333, 444, 555]\n\nIt returns 111 with probability 0.66 (10\/150) \nIt returns 222 with probability 0.13 (20\/150)\nIt returns 333 with probability 0.20 (30\/150)\nIt returns 444 with probability 0.26 (40\/150)\nIt returns 555 with probability 0.33 (50\/150)<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-cumulative-weights-to-choose-items-from-the-list-with-different-probability\"><strong>Cumulative weights to choose items from the list with different probability<\/strong><\/h2>\n\n\n\n<p>To make selections according to the cumulative weights, use the <code>cum_weights<\/code> parameter.<\/p>\n\n\n\n<p><strong><span style=\"color: #ff6600;\">Note: <\/span><\/strong>Python converts the relative weights to cumulative weights before making selections. So, I suggest you pass cumulative weights to saves time and extra work.<\/p>\n\n\n\n<p>he cumulative weight of each element is determined by using the following formula.<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">cum_weight= Weight of previous element + own weight<\/pre>\n\n\n\n<p>For example, the relative weights <code>[5, 10, 15, 20]<\/code> are equivalent to the cumulative weights <code>[5, 15, 30, 50]<\/code>.<\/p>\n\n\n\n<p>Let&#8217;s see how to use cumulative weights to choose 4 elements from a list with different probability.<\/p>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code3\"  class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-5\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">import<\/span> random\n\nnameList = &#91;<span class=\"hljs-string\">\"Kelly\"<\/span>, <span class=\"hljs-string\">\"Scott\"<\/span>, <span class=\"hljs-string\">\"Emma\"<\/span>, <span class=\"hljs-string\">\"Jon\"<\/span>]\nprint(random.choices(nameList, cum_weights=(<span class=\"hljs-number\">5<\/span>, <span class=\"hljs-number\">15<\/span>, <span class=\"hljs-number\">30<\/span>, <span class=\"hljs-number\">50<\/span>), k=<span class=\"hljs-number\">4<\/span>))\n<span class=\"hljs-comment\"># Output &#91;'Jon', 'Kelly', 'Jon', 'Scott']<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-5\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code3', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><button class=\"hljs-run-button\" onclick=\"run_code('code3');\"><i class=\"far fa-play-circle\" aria-hidden=\"true\"><\/i> Run<\/button><\/div>\n\n\n<h3 class=\"wp-block-heading\" id=\"h-choose-a-single-element-form-list-with-different-probability\">Choose a single element form list with different probability<\/h3>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code4\"  class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-6\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">import<\/span> random\n\nnames = &#91;<span class=\"hljs-string\">\"Kelly\"<\/span>, <span class=\"hljs-string\">\"Scott\"<\/span>, <span class=\"hljs-string\">\"Emma\"<\/span>, <span class=\"hljs-string\">\"Jon\"<\/span>]\n<span class=\"hljs-keyword\">for<\/span> i <span class=\"hljs-keyword\">in<\/span> range(<span class=\"hljs-number\">3<\/span>):\n    item = random.choices(names, cum_weights=(<span class=\"hljs-number\">5<\/span>, <span class=\"hljs-number\">15<\/span>, <span class=\"hljs-number\">30<\/span>, <span class=\"hljs-number\">50<\/span>), k=<span class=\"hljs-number\">1<\/span>)\n    print(<span class=\"hljs-string\">\"Iteration:\"<\/span>, i, <span class=\"hljs-string\">\"Weighted Random choice is\"<\/span>, item&#91;<span class=\"hljs-number\">0<\/span>])<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-6\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code4', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><button class=\"hljs-run-button\" onclick=\"run_code('code4');\"><i class=\"far fa-play-circle\" aria-hidden=\"true\"><\/i> Run<\/button><\/div>\n\n\n<p>Output:<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">Iteration: 0 Weighted Random choice is Jon\nIteration: 1 Weighted Random choice is Kelly\nIteration: 2 Weighted Random choice is Jon<\/pre>\n\n\n\n<p><strong>Note<\/strong>: we got &#8220;Jon&#8221; 3 times in the result because it has the highest probability of being selected<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-probability-of-getting-6-or-more-heads-from-10-spins\">Probability of getting 6 or more heads from 10 spins<\/h2>\n\n\n\n<p>Use the cumulative weights to set the probability of getting the head of a coin to 0.61, and the tail of a coin to 0.39 (1 \u2013 0.61 = 0.39)<\/p>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code5\"  class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-7\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">import<\/span> random\n\n<span class=\"hljs-comment\"># we specified head and tail of a coin in string<\/span>\ncoin = <span class=\"hljs-string\">\"HT\"<\/span>\n<span class=\"hljs-comment\"># Execute 3 times to verify we are getting 6 or more heads in every 10 spins<\/span>\n<span class=\"hljs-keyword\">for<\/span> i <span class=\"hljs-keyword\">in<\/span> range(<span class=\"hljs-number\">3<\/span>):\n    print(random.choices(coin, cum_weights=(<span class=\"hljs-number\">0.61<\/span>, <span class=\"hljs-number\">1.00<\/span>), k=<span class=\"hljs-number\">10<\/span>))<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-7\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code5', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><button class=\"hljs-run-button\" onclick=\"run_code('code5');\"><i class=\"far fa-play-circle\" aria-hidden=\"true\"><\/i> Run<\/button><\/div>\n\n\n<p>Output:<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">['H', 'H', 'H', 'H', 'H', 'H', 'H', 'T', 'H', 'T']\n['H', 'T', 'H', 'H', 'H', 'T', 'H', 'H', 'H', 'H']\n['H', 'T', 'T', 'T', 'H', 'T', 'H', 'H', 'H', 'H']<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-generate-weighted-random-numbers\">Generate weighted random numbers<\/h2>\n\n\n\n<p>Given a <strong>range of integers<\/strong>, we want to generate five <a href=\"https:\/\/pynative.com\/python-random-randrange\/\">random numbers<\/a> based on the weight. We need to specify the probability\/weight for each number to be selected. Let&#8217;s see how to generate random numbers with a given (numerical) distribution with different probability<\/p>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code6\"  class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-8\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">import<\/span> random\n\n<span class=\"hljs-comment\"># Generate 6 random numbers from a given range with weighted probability<\/span>\nnumbers = random.choices(range(<span class=\"hljs-number\">10<\/span>, <span class=\"hljs-number\">40<\/span>, <span class=\"hljs-number\">5<\/span>), cum_weights=(<span class=\"hljs-number\">5<\/span>, <span class=\"hljs-number\">15<\/span>, <span class=\"hljs-number\">10<\/span>, <span class=\"hljs-number\">25<\/span>, <span class=\"hljs-number\">40<\/span>, <span class=\"hljs-number\">65<\/span>), k=<span class=\"hljs-number\">6<\/span>)\nprint(numbers)\n<span class=\"hljs-comment\"># Output &#91;35, 35, 15, 10, 35, 35]<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-8\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code6', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><button class=\"hljs-run-button\" onclick=\"run_code('code6');\"><i class=\"far fa-play-circle\" aria-hidden=\"true\"><\/i> Run<\/button><\/div>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-points-to-remember-before-implementing-weighted-random-choices\">Points to remember before implementing weighted random choices<\/h2>\n\n\n\n<ul><li>If you don&#8217;t specify the relative or cumulative weight, the r<code>andom.choices()<\/code> will choose elements with equal probability.<\/li><li>The specified weights sequence must be of the same length as the population sequence.<\/li><li>Don&#8217;t specify relative weights and cumulative weight at the same time to avoid Type Error (<code>TypeError: Cannot specify both weights and cumulative weights<\/code>).<\/li><li>You can specify The weights or cum_weights only as integers, floats, and fractions but excludes decimals.<\/li><li>Weights must be non-negative.<\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"h-numpy-s-random-choice-to-choose-elements-from-the-list-with-different-probability\">Numpy&#8217;s <code>random.choice()<\/code> to choose elements from the list with different probability<\/h2>\n\n\n\n<p>If you are using Python version less than 3.6, you can use the NumPy library to make weighted random choices. Install numpy using a <code>pip install numpy<\/code>.<\/p>\n\n\n\n<p>Using a <code><a href=\"https:\/\/numpy.org\/doc\/stable\/reference\/random\/generated\/numpy.random.choice.html\" target=\"_blank\" rel=\"noreferrer noopener\">numpy.random.choice()<\/a><\/code> you can specify the probability distribution.<\/p>\n\n\n<pre id=\"syntax\" class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-9\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">numpy.random.choice(a,\u00a0size=<span class=\"hljs-literal\">None<\/span>,\u00a0replace=<span class=\"hljs-literal\">True<\/span>,\u00a0p=<span class=\"hljs-literal\">None<\/span>)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-9\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<ul><li><code>a<\/code>: It is the population from which you want to choose elements. for example, list.<\/li><li><code>size<\/code>: It is nothing but the number of elements you want to choose.<\/li><li><code>p<\/code>:  It Used to specify the probability for each element to be selected.<\/li><\/ul>\n\n\n\n<p><strong>Note<\/strong>: Probabilities must sum to 1, i.e., when you specify probability weights for each element, the sum of all weights must be 1.<\/p>\n\n\n\n<p><strong>Example<\/strong>:<\/p>\n\n\n<div class=\"hljstoolbar\"><pre id=\"code7\"  class=\"wp-block-code language-python\" aria-describedby=\"shcb-language-10\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">import<\/span> numpy <span class=\"hljs-keyword\">as<\/span> np\n\nnumberList = &#91;<span class=\"hljs-number\">100<\/span>, <span class=\"hljs-number\">200<\/span>, <span class=\"hljs-number\">300<\/span>, <span class=\"hljs-number\">400<\/span>]\n<span class=\"hljs-comment\"># Choose elements with different probabilities<\/span>\nsampleNumbers = np.random.choice(numberList, <span class=\"hljs-number\">4<\/span>, p=&#91;<span class=\"hljs-number\">0.10<\/span>, <span class=\"hljs-number\">0.20<\/span>, <span class=\"hljs-number\">0.30<\/span>, <span class=\"hljs-number\">0.40<\/span>])\nprint(sampleNumbers)\n<span class=\"hljs-comment\"># Output &#91;300 200 300 300]<\/span>\n<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-10\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre><button class=\"hljs-copy-button\" onclick=\"copy_code('code7', this);\"><i class=\"far fa-copy1\" aria-hidden=\"true\"><\/i><\/button><button class=\"hljs-run-button\" onclick=\"run_code('code7');\"><i class=\"far fa-play-circle\" aria-hidden=\"true\"><\/i> Run<\/button><\/div>\n\n\n<h2 class=\"wp-block-heading\" id=\"h-next-steps\">Next Steps<\/h2>\n\n\n\n<p>I want to hear from you. What do you think of this article? Or maybe I missed one of the ways to generate weighted random choices? Either way, let me know by&nbsp;<strong>leaving a comment below<\/strong>.<\/p>\n\n\n\n<p>Also, try to solve the following Free exercise&nbsp;and&nbsp;quiz to have a better understanding of&nbsp;<a href=\"https:\/\/pynative.com\/python\/random\/\">working with random data in Python<\/a>.<\/p>\n\n\n\n<ul><li><a href=\"https:\/\/pynative.com\/python-random-number-generation-exercise-questions-and-challenge\/\">Python random data generation Exercise<\/a>&nbsp;<\/li><li><a href=\"https:\/\/pynative.com\/python-random-data-generation-quiz\/\">Python random data generation Quiz<\/a><\/li><\/ul>\n","protected":false},"excerpt":{"rendered":"<p>This lesson demonstrates ways to choose single or multiple elements from the list randomly with a different probability. Use the random.choices() function to get the weighted random samples in Python. Also, See: Python random data generation Exercise Python random data generation Quiz Let&#8217;s take the following example for a better understanding of the requirement. If [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":7256,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[22,6],"tags":[27],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v22.6 (Yoast SEO v22.6) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Python Weighted Random Choices from the list with Probability<\/title>\n<meta name=\"description\" content=\"Weighted random choices in Python. Choose elements from the list randomly with a different probability. 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