Hyperparameters

A minimal utility for working with AWS Sagemaker hyperparameters. More broadly for dealing with environment variables. Two key functions:

• hyperparam reads the enviroment variable
• report_hyperparameters writes them to a JSON file, and logs them.

For purposes of this example we have the following environment variables set:

ENV["SM_HP_FOO"] = "1";
ENV["SM_HP_BAR"] = "2";
ENV["SM_HP_BAZ"] = "three";
ENV["SM_HP_QUX"] = "-3.14";

Sagemaker prefixes the environment variables it automatically defines for hyperparameters with SM_HP_.

We can access an enviroment variable by name using hyperparam:

julia> hyperparam(:foo)
1

We can tell it the type by passing that as the first argument:

julia> hyperparam(Float64, :bar)
2.0

If we don't it defaults to trying in order: Bool, Int, Float64 and finally falling back to assuming it is a String:

julia> hyperparam(:baz)
"three"

report_hyperparameters(directory) is used to output all the hyperparameters to the logs, and write a file called hyperparameters.json into the directory.

julia> using FilePathsBase

julia> report_hyperparameters(p".")
[info | Hyperparameters]: hyperparameters: baz=three
[info | Hyperparameters]: hyperparameters: bar=2.0
[info | Hyperparameters]: hyperparameters: qux=-3.14
[info | Hyperparameters]: hyperparameters: foo=1
[info | Hyperparameters]: Report: saving at ./hyperparameters.json
p"./hyperparameters.json"

The JSON file looks like:

{
    "baz": "three",
    "bar": 2.0,
    "qux": -3.14,
    "foo": 1
}

Notice two key things:

1. Even though qux was never accessed during our code, it is still saved as the environment variable existed with the right prefix. It's type was found with the same mechanism used if the type is not provided to hyperparam. Which determined it was a Float64 (and not a String).
2. When we accessed bar passing in the type, that type was remembered, so even though the enviroment variables just contained 2, the report correctly read 2.0