I have, for example, this table

+-----------------+
| fruit  | weight |
+-----------------+
| apple  |   4    |
| orange |   2    |
| lemon  |   1    |
+-----------------+

I need to return random fruit. But apple should be picked 4 times frequently then lemon and 2 times frequently then orange.

In more general case it should be f(weight) times frequently.

What is general algorithm to implement this behavior?

Or maybe there is some ready gems on Ruby? :)

PS I've implemented current algorithm in Ruby https://github.com/fl00r/pickup

I have, for example, this table

+-----------------+
| fruit  | weight |
+-----------------+
| apple  |   4    |
| orange |   2    |
| lemon  |   1    |
+-----------------+

I need to return a random fruit. But apple should be picked 4 times as frequent as Lemon and 2 times as frequent as orange.

In more general case it should be f(weight) times frequently.

What is a good general algorithm to implement this behavior?

Or maybe there are some ready gems on Ruby? :)

PS 
I've implemented current algorithm in Ruby https://github.com/fl00r/pickup

I have, for example, this table

+-----------------+
| fruit  | weight |
+-----------------+
| apple  |   4    |
| orange |   2    |
| lemon  |   1    |
+-----------------+

I need to return random fruit. But apple should be picked 4 times frequently then lemon and 2 times frequently then orange.

In more general case it should be f(weight) times frequently.

What is general algorithm to implement this behavior?

Or maybe there is some ready gems on Ruby? :)

PS I've implemented current algorithm in Ruby https://github.com/fl00r/pickup

I have, for example, this table

+-----------------+
| fruit  | weight |
+-----------------+
| apple  |   4    |
| orange |   2    |
| lemon  |   1    |
+-----------------+

I need to return random fruit. But apple should be picked 4 times frequently then lemon and 2 times frequently then orange.

In more general case it should be f(weight) times frequently.

What is general algorithm to implement this behavior?

Or maybe there is some ready gems on Ruby? :)

PS I've implemented current algorithm in Ruby https://github.com/fl00r/pickup