I am looking for a way to calculate how similar each number is compared to every other number in a set. Here's an example:
`[61, 62, 59, 60, 63, 62, 58]` would have a high similarity score, where as `[12, 96, 71, 66, 108, 23, 5, 59]` would have a low similarity score.

Is there a term for this, and how would I calculate it?
Yes, the term you may be looking for is variance or standard deviation. Variance and standard deviation are statistical measures that indicate the dispersion or spread of a set of numbers. A smaller variance or standard deviation implies that the numbers are closer together, whereas a larger one implies the numbers are more spread out.

In your case, you can use standard deviation as a similarity score. Lower standard deviation means higher similarity, and higher standard deviation means lower similarity.

Here's how to calculate the standard deviation:

1. Calculate the mean (average) of the numbers in the dataset.
2. Subtract the mean from each number and square the result.
3. Calculate the mean of the squared differences.
4. Take the square root of the mean of the squared differences.

Using the two arrays you gave. Here's a step-by-step example of computing the standard deviation:

Let's start with the first array `[61, 62, 59, 60, 63, 62, 58]`:

1. Calculate the mean (average) of the numbers in the dataset.
(61 + 62 + 59 + 60 + 63 + 62 + 58) / 7 = 425 / 7 = 60.714

2. Subtract the mean from each number and square the result.
(61 - 60.714)^2 = 0.085
(62 - 60.714)^2 = 1.647
(59 - 60.714)^2 = 2.947
(60 - 60.714)^2 = 0.510
(63 - 60.714)^2 = 5.247
(62 - 60.714)^2 = 1.647
(58 - 60.714)^2 = 7.347

3. Calculate the mean of the squared differences.
(0.085 + 1.647 + 2.947 + 0.510 + 5.247 + 1.647 + 7.347) / 7 = 18.48 / 7 = 2.640

4. Take the square root of the mean of the squared differences.
sqrt(2.640) = 1.625

The standard deviation for the first array is approximately 1.625.

Now for the second array `[12, 96, 71, 66, 108, 23, 5, 59]`:

1. Calculate the mean (average) of the numbers in the dataset.
(12 + 96 + 71 + 66 + 108 + 23 + 5 + 59) / 8 = 440 / 8 = 55

2. Subtract the mean from each number and square the result.
(12 - 55)^2 = 1849
(96 - 55)^2 = 1681
(71 - 55)^2 = 256
(66 - 55)^2 = 121
(108 - 55)^2 = 2809
(23 - 55)^2 = 1024
(5 - 55)^2 = 2500
(59 - 55)^2 = 16

3. Calculate the mean of the squared differences.
(1849 + 1681 + 256 + 121 + 2809 + 1024 + 2500 + 16) / 8 = 10256 / 8 = 1282

4. Take the square root of the mean of the squared differences.
sqrt(1282) = 35.818

The standard deviation for the second array is approximately 35.818.

So, the standard deviation (similarity score) for the first array is 1.625, and for the second array, it is 35.818. A lower score indicates higher similarity.
Is standart deviation the thing that shows up in graph as the shaded part of projections to show uncertainty?
Yes, that is correct. The standard deviation is a measure of how spread out data is. It is calculated by taking the square root of the variance. The variance is a measure of how much the data points vary from the mean.

The standard deviation is often used to show uncertainty in projections. For example, if you have a projection that shows the average temperature will be 50 degrees Fahrenheit, with a standard deviation of 5 degrees Fahrenheit, that means that the temperature could be anywhere from 45 degrees Fahrenheit to 55 degrees Fahrenheit.

The standard deviation is a useful tool for understanding uncertainty. It can help you to make decisions about how to plan for the future.