Convert a vector to map in Terraform

Terraform
1

I’m getting a vector of arns of alarms from cloudwatch and I’d like to take those arns and put them on a map, each key having 10 arns. The key would be formed by ALARM_NAME_INDEX, with the index being a counter.

Alarm:

resource "aws_cloudwatch_metric_alarm" "test" {
  count = length(data.aws_instances.test.ids)
  alarm_name                = "alarm_test_{data.aws_instances.test.ids[count.index]}"
  comparison_operator       = "GreaterThanOrEqualToThreshold"
  evaluation_periods        = "2"
  metric_name               = "CPUUtilization"
  namespace                 = "AWS/EC2"
  period                    = "120"
  statistic                 = "Average"
  threshold                 = "80"
  alarm_description         = "This metric monitors ec2 cpu utilization"
  insufficient_data_actions = []
  dimensions = {
    InstanceId = data.aws_instances.test.ids[count.index]
}

Currently, I’m putting all the arns in a vector in just one key of a map:

output "test1" {
    value = tomap({
             "Alarm" = aws_cloudwatch_metric_alarm.test.*.arn
       )}
}

An example of what I want to do:

Ex: Supports having 35 arns of alarms in a vector to convert into a map

{Alarm_1, 10 arns},
{Alarm_2, 10 arns},
{Alarm_3, 5 arns}
2

Something like this, then?

> {for index, items in chunklist(["alpha", "beta", "gamma", "delta", "epsilon", "zeta", "eta", "theta"], 3): "Greek_${index}" => items}
{
  "Greek_0" = tolist([
    "alpha",
    "beta",
    "gamma",
  ])
  "Greek_1" = tolist([
    "delta",
    "epsilon",
    "zeta",
  ])
  "Greek_2" = tolist([
    "eta",
    "theta",
  ])
}