问题：调用lightgbm库，设置了早停轮次“early_stopping_rounds”参数和打印log间隔“verbose_eval”参数后出现UserWarning
示例代码如下：
for num_leaves in range(5,100,5):
for max_depth in range(3,8,1):
params['num_leaves'] = num_leaves
params['max_depth'] = max_depth
cv_results = lgb.cv(
params,
lgb_train,
seed=1,
nfold=5,
metrics='auc',
early_stopping_rounds=30, ###################
verbose_eval=True ####################
)
mean_auc = pd.Series(cv_results['auc-mean']).max()
boost_rounds = pd.Series(cv_results['auc-mean']).idxmax()
if mean_auc >= max_auc:
max_auc = mean_auc
best_params['num_leaves'] = num_leaves
best_params['max_depth'] = max_depth
if 'num_leaves' and 'max_depth' in best_params.keys():
params['num_leaves'] = best_params['num_leaves']
params['max_depth'] = best_params['max_depth']
两个UserWarning如下：
UserWarning: 'early_stopping_rounds' argument is deprecated and will be removed in a future release of LightGBM. Pass 'early_stopping()' callback via 'callbacks' argument instead.
UserWarning: 'verbose_eval' argument is deprecated and will be removed in a future release of LightGBM. Pass 'log_evaluation()' callback via 'callbacks' argument instead.
解决：将代码做如下修改
from lightgbm import log_evaluation, early_stopping
callbacks = [log_evaluation(period=30), early_stopping(stopping_rounds=30)]
for num_leaves in range(5,100,5):
for max_depth in range(3,8,1):
params['num_leaves'] = num_leaves
params['max_depth'] = max_depth
cv_results = lgb.cv(
params,
lgb_train,
seed=1,
nfold=5,
metrics='auc',
callbacks=callbacks ############################
)
mean_auc = pd.Series(cv_results['auc-mean']).max()
boost_rounds = pd.Series(cv_results['auc-mean']).idxmax()
if mean_auc >= max_auc:
max_auc = mean_auc
best_params['num_leaves'] = num_leaves
best_params['max_depth'] = max_depth
if 'num_leaves' and 'max_depth' in best_params.keys():
params['num_leaves'] = best_params['num_leaves']
params['max_depth'] = best_params['max_depth']
即按照警告中的要求，首先from lightgbm import log_evaluation, early_stopping ，
之后用callbacks = [log_evaluation(period=30), early_stopping(stopping_rounds=30)]
替换之前的'verbose_eval'以及'early_stopping_rounds'即可:)
