Unable to suppress parameter alias related warnings

[memeplex]

Description

Many parameter aliases trigger warnings that may be annoying and repetitive, specially in the context of model selection using grid search. These warnings can't be silenced except by changing the parameter to some specific alias. Often, this specific alias is not the one "recommended" (most used or first listed) in the documentation.

Reproducible example

See #3641 (comment)

Environment info

LightGBM version or commit hash: 3.2.1

[StrikerRUS]

@jameslamb I believe it's rather bug than feature request. Users ask to not print warnings (via verbose=-1) but this one is printed.

[jameslamb]

sure, fine with me

[rm17tink]

None of these comments or links work. They are circuitous to suppressing the [LightGBM] [Warning]

[StrikerRUS]

@rm17tink What exact warning you're trying to suppress? We aren't aware of any warnings other than

[LightGBM] [Warning] param_alias_1 is set=xxx, param_alias_2=yyy will be ignored. Current value: param_alias_1=xxx

which cannot be suppressing by verbosity=-1.

[jmoralez]

These warnings are coming from

LightGBM/include/LightGBM/config.h

Line 1135 in 23da5fc

static void KeyAliasTransform(std::unordered_map<std::string, std::string>* params) {

which is called before setting the logging level. I believe if we set the logging level before this:

LightGBM/src/io/config.cpp

Line 45 in 23da5fc

ParameterAlias::KeyAliasTransform(&params);

we can fix the issue. I've tried it locally and it works, I'm jut not sure if it's the right thing, so I'd like to discuss this first before opening a PR.

[StrikerRUS]

I believe if we set the logging level before this

How will we know a requested logging level without parsing user's params (verbosity param to be more precise)?
#3641 (comment)

[jmoralez]

What I was doing was something like:

int verbosity = Config().verbosity
GetInt(&verbosity, params, "verbose")
GetInt(&verbosity, params, "verbosity") 

before the alias call. So the default verbosity is used if it wasn't specified or it is set to what the user specified, and then the aliases are resolved for the other params.

[jameslamb]

I like your approach @jmoralez ! I'd support special handling of verbosity in ParameterAlias::KeyAliasTransform() to ensure that all log messages can be controlled by verbose.

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