new random concept (#3556)

* new `random` concept

* changed unused variables to underscore

* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

I have been avoiding $\LaTeX$ (very reluctantly, but Jeremy and Erik insist). I guess Unicode will save us here.

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Update concepts/random/about.md

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* Added Introduction.md and Links

* Small touchups and link fixes

* More Typo Fixes

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concepts/random/.meta/config.json

@@ -0,0 +1,5 @@
+{
+  "blurb": "The random module contains functionality to generate random values for modelling, simulations and games. It should not be used for security or cryptographic applications.",
+  "authors": ["BethanyG", "colinleach"],
+  "contributors": []
+}

concepts/random/about.md

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+# About
+
+Many programs need (apparently) random values to simulate real-world events.
+
+Common, familiar examples include:
+- A coin toss: a random value from `('H', 'T')`.
+- The roll of a die: a random integer from 1 to 6.
+- Shuffling a deck of cards: a random ordering of a card list.
+
+Generating truly random values with a computer is a [surprisingly difficult technical challenge][truly-random], so you may see these results referred to as "pseudorandom".
+
+In practice, a well-designed library like the [`random`][random] module in the Python standard library is fast, flexible, and gives results that are amply good enough for most applications in modelling, simulation and games.
+
+The rest of this page will list a few of the most common functions in `random`.
+We encourage you to explore the full `random` documentation, as there are many more options than what we cover here.
+
+
+
+~~~~exercism/caution
+
+The `random` module should __NOT__ be used for security and cryptographic applications.
+
+Instead, Python provides the [`secrets`][secrets] module.
+This is specially optimized for cryptographic security.
+Some of the prior issues and reasons for creating the secrets module can be found in [PEP 506][PEP 506].
+
+[secrets]: https://docs.python.org/3.11/library/secrets.html#module-secrets
+[PEP 506]: https://peps.python.org/pep-0506/
+~~~~
+
+
+
+## Importing
+
+Before you can utilize the tools in the `random` module, you must first import it:
+
+```python
+>>> import random
+
+# Choose random integer from a range
+>>> random.randrange(1000)
+360
+
+>>> random.randrange(-1, 500)
+228
+
+>>> random.randrange(-10, 11, 2)
+-8
+
+# Choose random integer between two values (inclusive)
+>>> random.randint(5, 25)
+22
+
+```
+
+To avoid typing the name of the module, you can import specific functions by name:
+
+```python
+>>> from random import choice, choices
+
+# Using choice() to pick Heads or Tails 10 times
+>>> tosses = []
+>>> for side in range(10):
+>>>    tosses.append(choice(['H', 'T']))    
+
+>>> print(tosses)
+['H', 'H', 'H', 'H', 'H', 'H', 'H', 'T', 'T', 'H']
+
+
+# Using choices() to pick Heads or Tails 8 times
+>>> picks = []
+>>> picks.extend(choices(['H', 'T'], k=8))
+>>> print(picks)
+['T', 'H', 'H', 'T', 'H', 'H', 'T', 'T']
+```
+
+
+## Creating random integers
+
+The `randrange()` function has three forms, to select a random value from `range(start, stop, step)`:
+  1.  `randrange(stop)` gives an integer `n` such that `0 <= n < stop`
+  2.   `randrange(start, stop)` gives an integer `n` such that `start <= n < stop`
+  3.  `randrange(start, stop, step)` gives an integer `n` such that `start <= n < stop` and `n` is in the sequence `start, start + step, start + 2*step...`
+
+For the common case where `step == 1`, the `randint(a, b)` function may be more convenient and readable.
+Possible results from `randint()` _include_ the upper bound, so `randint(a, b)` is the same as using `randrange(a, b+1)`:
+
+```python
+>>> import random
+
+# Select one number at random from the range 0, 499
+>>> random.randrange(500)
+219
+
+# Select 10 numbers at random between 0 and 9 two steps apart.
+>>> numbers = []
+>>> for integer in range(10):
+>>>    numbers.append(random.randrange(0, 10, 2))
+>>> print(numbers)
+[2, 8, 4, 0, 4, 2, 6, 6, 8, 8]
+
+# roll a die
+>>> random.randint(1, 6)  
+4
+```
+
+
+
+## Working with sequences
+
+The functions in this section assume that you are starting from some [sequence][sequence-types], or other container.
+
+
+This will typically be a `list`, or with some limitations a `tuple` or a `set` (_a `tuple` is immutable, and `set` is unordered_).
+
+
+
+### `choice()` and `choices()`
+
+The `choice()` function will return one entry chosen at random from a given sequence.
+At its simplest, this might be a coin-flip:
+
+```python
+# This will pick one of the two values in the list at random 5 separate times 
+>>> [random.choice(['H', 'T']) for _ in range(5)]
+['T', 'H', 'H', 'T', 'H']
+
+We could accomplish essentially the same thing using the `choices()` function, supplying a keyword argument with the list length:
+
+
+```python
+>>> random.choices(['H', 'T'], k=5)
+['T', 'H', 'T', 'H', 'H']
+```
+
+
+In the examples above, we assumed a fair coin with equal probability of heads or tails, but weights can also be specified.
+For example, if a bag contains 10 red balls and 15 green balls, and we would like to pull one out at random:
+
+```python
+>>> random.choices(['red', 'green'], [10, 15])
+['red']
+```
+
+
+
+### `sample()`
+
+The `choices()` example above assumes what statisticians call ["sampling with replacement"][sampling-with-replacement].
+Each pick or choice has **no effect** on the probability of future choices, and the distribution of potential choices remains the same from pick to pick.
+
+
+In the example with red and green balls: after each choice, we _return_ the ball to the bag and shake well before the next pick.
+This is in contrast to a situation where we pull out a red ball and _it stays out_.
+Not returning the ball means there are now fewer red balls in the bag, and the next choice is now _less likely_ to be red.
+
+To simulate this "sampling without replacement", the random module provides the `sample()` function.
+The syntax of `sample()` is similar to `choices()`, except it adds a `counts` keyword parameter:
+
+
+```python
+>>> random.sample(['red', 'green'], counts=[10, 15], k=10)
+['green', 'green', 'green', 'green', 'green', 'red', 'red', 'red', 'red', 'green']
+```
+
+Samples are returned in the order they were chosen.
+
+
+
+### `shuffle()`
+
+Both `choices()` and `sample()` return new lists when `k > 1`.
+In contrast, `shuffle()` randomizes the order of a list _**in place**_, and the original ordering is lost:
+
+```python
+>>> my_list = [1, 2, 3, 4, 5]
+>>> random.shuffle(my_list)
+>>> my_list
+[4, 1, 5, 2, 3]
+```
+
+
+## Working with Distributions
+
+Until now, we have concentrated on cases where all outcomes are equally likely.
+For example, `random.randrange(100)` is equally likely to give any integer from 0 to 99.
+
+Many real-world situations are far less simple than this.
+As a result, statisticians have created a wide variety of [`distributions`][probability-distribution] to describe "real world" results mathematically.
+
+
+
+### Uniform distributions
+
+For integers, `randrange()` and `randint()` are used when all probabilities are equal.
+This is called a [`uniform`][uniform-distribution] distribution.
+
+
+There are floating-point equivalents to `randrange()` and `randint()`.
+
+__`random()`__ gives a `float` value `x` such that `0.0 <= x < 1.0`.
+
+__`uniform(a, b)`__ gives `x` such that `a <= x <= b`.
+
+```python
+>>> [round(random.random(), 3) for _ in range(5)]
+[0.876, 0.084, 0.483, 0.22, 0.863]
+
+>>> [round(random.uniform(2, 5), 3) for _ in range(5)]
+[2.798, 2.539, 3.779, 3.363, 4.33]
+```
+
+
+
+### Gaussian distribution
+
+Also called the "normal" distribution or the "bell-shaped" curve, this is a very common way to describe imprecision in measured values.
+
+For example, suppose the factory where you work has just bought 10,000 bolts which should be identical.
+You want to set up the factory robot to handle them, so you weigh a sample of 100 and find that they have an average (or `mean`) weight of 4.731g.
+This is extremely unlikely to mean that they all weigh exactly 4.731g.
+Perhaps you find that values range from 4.627 to 4.794g but cluster around 4.731g.
+
+This is the [`Gaussian distribution`][gaussian-distribution], for which probabilities peak at the mean and tails off symmetrically on both sides (hence "bell-shaped").
+To simulate this in software, we need some way to specify the width of the curve (_typically, expensive bolts will cluster more tightly around the mean than cheap bolts!_).
+
+By convention, this is done with the [`standard deviation`][standard-deviation]: small values for a sharp, narrow curve, large for a low, broad curve.
+Mathematicians love Greek letters, so we use `μ` ('mu') to represent the mean and `σ` ('sigma') to represent the standard deviation.
+Thus, if you read that "95% of values are within 2σ of μ" or "the Higgs boson has been detected with 5-sigma confidence", such comments relate to the standard deviation.
+
+```python
+>>> mu = 4.731
+>>> sigma = 0.316
+>>> [round(random.gauss(mu, sigma), 3) for _ in range(5)]
+[4.72, 4.957, 4.64, 4.556, 4.968]
+```
+
+[gaussian-distribution]: https://simple.wikipedia.org/wiki/Normal_distribution
+[probability-distribution]: https://simple.wikipedia.org/wiki/Probability_distribution
+[random]: https://docs.python.org/3/library/random.html
+[sampling-with-replacement]: https://www.youtube.com/watch?v=LnGFL_A6A6A
+[sequence-types]: https://docs.python.org/3/library/stdtypes.html#sequence-types-list-tuple-range
+[standard-deviation]: https://simple.wikipedia.org/wiki/Standard_deviation
+[truly-random]: https://www.malwarebytes.com/blog/news/2013/09/in-computers-are-random-numbers-really-random
+[uniform-distribution]: https://www.investopedia.com/terms/u/uniform-distribution.asp#:~:text=In%20statistics%2C%20uniform%20distribution%20refers,a%20spade%20is%20equally%20likely.

concepts/random/introduction.md

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+# Introduction
+
+Many programs need (apparently) random values to simulate real-world events.
+
+Common, familiar examples include:
+- A coin toss: a random value from `('H', 'T')`.
+- The roll of a die: a random integer from 1 to 6.
+- Shuffling a deck of cards: a random ordering of a card list.
+- The creation of trees and bushes in a 3-D graphics simulation.
+
+Generating _truly_ random values with a computer is a [surprisingly difficult technical challenge][truly-random], so you may see these results referred to as "pseudorandom".
+
+In practice, a well-designed library like the [`random`][random] module in the Python standard library is fast, flexible, and gives results that are amply good enough for most applications in modelling, simulation and games.
+
+For this brief introduction, we show the four most commonly used functions from the module.
+We encourage you to explore the full [`random`][random] documentation, as there are many tools and options.
+
+
+~~~~exercism/caution
+
+The `random` module should __NOT__ be used for security and cryptographic applications!!
+
+Instead, Python provides the [`secrets`][secrets] module.
+This is specially optimized for cryptographic security.
+Some of the prior issues and reasons for creating the secrets module can be found in [PEP 506][PEP 506].
+
+[secrets]: https://docs.python.org/3.11/library/secrets.html#module-secrets
+[PEP 506]: https://peps.python.org/pep-0506/
+~~~~
+
+
+Before you can utilize the tools in the `random` module, you must first import it:
+
+```python
+>>> import random
+
+# Choose random integer from a range
+>>> random.randrange(1000)
+360
+
+>>> random.randrange(-1, 500)
+228
+
+>>> random.randrange(-10, 11, 2)
+-8
+
+# Choose random integer between two values (inclusive)
+>>> random.randint(5, 25)
+22
+
+```
+
+To avoid typing the name of the module, you can import specific functions by name:
+
+```python
+>>> from random import choice, choices
+
+# Using choice() to pick Heads or Tails 10 times
+>>> tosses = []
+>>> for side in range(10):
+>>>    tosses.append(choice(['H', 'T']))    
+
+>>> print(tosses)
+['H', 'H', 'H', 'H', 'H', 'H', 'H', 'T', 'T', 'H']
+
+
+# Using choices() to pick Heads or Tails 8 times
+>>> picks = []
+>>> picks.extend(choices(['H', 'T'], k=8))
+>>> print(picks)
+['T', 'H', 'H', 'T', 'H', 'H', 'T', 'T']
+```
+
+
+
+## `randrange()` and `randint()`
+
+Shown in the first example above, the `randrange()` function has three forms:
+
+1. `randrange(stop)` gives an integer `n` such that `0 <= n < stop`
+2. `randrange(start, stop)` gives an integer `n` such that `start <= n < stop`
+3. `randrange(start, stop, step)` gives an integer `n` such that `start <= n < stop`
+    and `n` is in the sequence `start, start + step, start + 2*step...`
+
+For the most common case where `step == 1`, `randint(a, b)` may be more convenient and readable.
+Possible results from `randint()` _include_ the upper bound, so `randint(a, b)` is the same as using `randrange(a, b+1)`.
+
+
+
+## `choice()` and `choices()`
+
+These two functions assume that you are starting from some [sequence][sequence-types], or other container.
+This will typically be a `list`, or with some limitations a `tuple` or a `set` (_a `tuple` is immutable, and `set` is unordered_).
+
+The `choice()` function will return one entry chosen at random from a given sequence, and `choices()` will return `k` number of entries chosen at random from a given sequence.
+In the examples shown above, we assumed a fair coin with equal probability of heads or tails, but weights can also be specified.
+
+For example, if a bag contains 10 red balls and 15 green balls, and we would like to pull one out at random:
+
+
+```python
+>>> random.choices(['red', 'green'], [10, 15])
+['red']
+```
+
+[random]: https://docs.python.org/3/library/random.html
+[sequence-types]: https://docs.python.org/3/library/stdtypes.html#sequence-types-list-tuple-range
+[truly-random]: https://www.malwarebytes.com/blog/news/2013/09/in-computers-are-random-numbers-really-random

concepts/random/links.json

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+[
+  {
+    "url": "https://docs.python.org/3/library/random.html/",
+    "description": "Official documentation for the random module."
+  },
+  {
+    "url": "https://engineering.mit.edu/engage/ask-an-engineer/can-a-computer-generate-a-truly-random-number/",
+    "description": "MIT Engineering: Can a computer generate a truly random number?"
+  },
+    {
+    "url": "https://www.malwarebytes.com/blog/news/2013/09/in-computers-are-random-numbers-really-random",
+    "description": "Are Random Numbers Really Random?"
+  }
+]

config.json

@@ -2573,6 +2573,11 @@
       "slug": "with-statement",
       "name": "With Statement"
     },
+    {
+      "uuid": "af6cad74-50c2-48f4-a6ce-cfeb72548d00",
+      "slug": "random",
+      "name": "Random"
+    },
     {
       "uuid": "000e7768-38b9-4904-9ae2-9a4e448f366c",
       "slug": "fractions",