Source
r/Puppet•
linuxdragons

Get index of value from an array?

I am not sure why I am struggling so much with this. Maybe because I am not overly familiar with Ruby?

I have a hash that I am passing to map() and I need to know my position while iterating inside map() (e.g. I am on X pass inside the map). It appears that I can retrieve the hash index, but not the position.

Okay, no big deal I guess. I extract the keys of my hash into a $hash_keys variable. Now inside of map() I want to search $hash_keys for a key and retrieve the array index (e.g. the position). Except now I don't see a function to search an array for a value and return its index.

What is the function I am looking for and why does it feel like I am going against the grain so much here?

​

Edit: I found a workaround

$hash_with_splay = $hash.reduce({}) |$return, $hash_item| {

$item_key = $hash_item[0]

$item_value = $hash_item[1]

$splay = Integer($return.length) / Integer(10)

$item_value_with_splay = $item_value + {'splay' => $splay }

$return + { $item_key => $item_value_with_splay }

}

Posted Feb 25, 2020, 6:05 PM UTC · edited

16
binford2k•

What’s the actual problem you’re trying to solve here?

1
linuxdragonsOP•

I have a hiera hash with many Cron job configurations. I need to splay these Cron jobs to spread their load. I have a property to manually define splay, but I would like to add an algorithm that auto calculates splay if not provided. As an example, I would like to increment the Cron jobs splay by 1 minute for every 10 Cron jobs (100+ Cron jobs per server). To auto calculate this I am running the hash through map, which is where my question starts.

1
binford2k•

What about something like:

slice($data, 10).each |$index, $value| {
  # extract parameters from $value

  cron { $uniquename:
    ...
    minute => $index % 60,
  }
}
1
linuxdragonsOP•

The slice function is interesting, but would really like to compute a hash where the splay value has been added. I would need to significantly restructure my code otherwise.

1
linuxdragonsOP•

I found a workaround. I switched to using reduce() and I "rebuilding" the hash. In each iteration of reduce() I check the new hash's length and use that for calculating splay.

1
binford2k•

Cool cool. Here's a trick; indent each line of a code block and it displays as a block that's a bit more readable.

$hash_with_splay = $hash.reduce({}) |$return, $hash_item| {
    $item_key = $hash_item[0]
    $item_value = $hash_item[1]
    $splay = Integer($return.length) / Integer(10)
    $item_value_with_splay = $item_value + {'splay' => $splay }
    $return + { $item_key => $item_value_with_splay }
}

https://www.reddit.com/wiki/markdown#wiki_code_blocks_and_inline_code

2