find the variance of all keys in a map in typescript

To find the variance of all keys in a Map in TypeScript, you can use the following code:

index.ts
function mapKeyVariance(map: Map<any, any>): number {
  const sum = Array.from(map.keys()).reduce((acc, cur) => acc + cur, 0);
  const mean = sum / map.size;
  const varianceSum = Array.from(map.keys()).reduce(
    (acc, cur) => acc + Math.pow(cur - mean, 2),
    0
  );
  const variance = varianceSum / map.size;
  return variance;
}
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This function takes in a Map object as an argument and returns the variance of all its keys.

First, we calculate the mean value of all the keys in the map by summing up all the keys and dividing by the total number of keys.

Then, we calculate the variance of all the keys in the map by taking each key, subtracting the mean from it, squaring the result, and adding it to the sum of the previous squared differences. Finally, we divide this sum by the total number of keys to get the variance.

You can call this function with any Map object that has keys of numerical type, such as integers or decimals.