find the standard deviation of all keys in a map in ruby

To find the standard deviation of all keys in a map in Ruby, we first need to extract the keys from the map and store them in an array. We can then use the built-in mean and standard_deviation methods from the descriptive_statistics gem to calculate the standard deviation.

Here's an example code snippet that demonstrates this approach:

main.rb
require 'descriptive_statistics'

# create a sample map
map = { 1 => 10, 2 => 20, 3 => 30, 4 => 40, 5 => 50 }

# extract the keys and store them in an array
keys = map.keys

# calculate the standard deviation
sd = keys.standard_deviation

puts "Standard deviation of keys: #{sd}"
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In this example, we use the keys method to extract the keys from the map and store them in the keys array. We then call the standard_deviation method on this array to calculate the standard deviation of the keys. Finally, we print out the result using puts.