[bug] Fix an error caused by infinity in trial.values

[nabenabe0928]

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This repository (optuna-dashboard) and Goptuna share common code.
This pull request may therefore be ported to Goptuna.
Make sure that you understand the consequences concerning licenses and check the box below if you accept the term before creating this pull request.

• I agree this patch may be ported to Goptuna by other Goptuna contributors.

Reference Issues/PRs

This PR addresses the issue discussed in PR#718.
Basically, when trial.values includes inf or -inf, which is a string, but not number, the Number maps them to nan.
Therefore, this PR circumvents this problem by mapping TrialValueNumber to number.

What does this implement/fix? Explain your changes.

This PR simply maps inf to Infinity and -inf to -Infinity.

You can simply check the behavior of the modification using:

type TrialValueNumber = number | "inf" | "-inf"

const convertTrialValueToNumber = (value: TrialValueNumber): number => {
    // TrialValueNumber takes `number`, "inf", or "-inf".
    return typeof(value) === "number" ? value : value.includes("-") ? -Infinity : Infinity
};

const targetValues: TrialValueNumber[] = [1, "inf", "-inf"]
for (const target of targetValues){
    const val = convertTrialValueToNumber(target)
    console.log(`Converted Value is ${val} with the type ${typeof(val)}`)
}

const convertedValues = targetValues.map((v) => convertTrialValueToNumber(v))
console.log(convertedValues.slice().sort((a, b) => a - b))

We can run this file by the following when the file name is debug.ts:

$ tsc debug.ts
$ node debug.js

The output in my environment was:

Converted Value is 1 with the type number
Converted Value is Infinity with the type number
Converted Value is -Infinity with the type number
[ -Infinity, 1, Infinity ]

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (9e314a9) 67.20% compared to head (bdd2759) 67.20%.
Report is 19 commits behind head on main.

Files	Patch %	Lines
optuna_dashboard/_app.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #724   +/-   ##
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  Coverage   67.20%   67.20%           
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  Files          35       35           
  Lines        2293     2293           
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  Hits         1541     1541           
  Misses        752      752           

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[HideakiImamura]

LGTM.

[c-bata]

LGTM 👍