fix bug in reset config for dataset

[guolinke]

to fix #2452

[aprilffff]

to fix #2452

should add const Dataset* train_data in function declaration?

[aprilffff]

still not work

[guolinke]

@aprilffff
before nv.model.reset_parameter({'feature_contri':new_fb.tolist()}), you should try to reset parameter to train-set as well.

LightGBM/python-package/lightgbm/basic.py

Lines 1167 to 1175 in 00d1e69

	def _update_params(self, params):
	if self.handle is not None and params is not None:
	_safe_call(_LIB.LGBM_DatasetUpdateParam(self.handle, c_str(param_dict_to_str(params))))
	if not self.params:
	self.params = copy.deepcopy(params)
	else:
	self.params_back_up = copy.deepcopy(self.params)
	self.params.update(params)
	return self

[aprilffff]

I tried this code in the callback function but still not work
params={'feature_contrib':fblist}
env.params.update(params)
env.model.train_set._update_params(params)
env.model.reset_parameter(params)

[aprilffff]

Dont worry, your advice is right. It's completely fixed now. Thx.