[ruby] How do I pick randomly from an array?

arr = [1,9,5,2,4,9,5,8,7,9,0,8,2,7,5,8,0,2,9]
arr[rand(arr.count)]

This will return a random element from array.

If You will use the line mentioned below

arr[1+rand(arr.count)]

then in some cases it will return 0 or nil value.

The line mentioned below

rand(number)

always return the value from 0 to number-1.

If we use

1+rand(number)

then it may return number and arr[number] contains no element.

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