请原谅我蹩脚的英语。这是代码。
def scoreClickAUC(num_clicks, num_impressions, predicted_ctr):
"""
Calculates the area under the ROC curve (AUC) for click rates
Parameters
----------
num_clicks : a list containing the number of clicks
num_impressions : a list containing the number of impressions
predicted_ctr : a list containing the predicted click-through rates
Returns
-------
auc : the area under the ROC curve (AUC) for click rates
"""
i_sorted = sorted(range(len(predicted_ctr)),key=lambda i: predicted_ctr[i],
reverse=True)
auc_temp = 0.0
click_sum = 0.0
old_click_sum = 0.0
no_click = 0.0
no_click_sum = 0.0
# treat all instances with the same predicted_ctr as coming from the
# same bucket
last_ctr = predicted_ctr[i_sorted[0]] + 1.0
for i in range(len(predicted_ctr)):
if last_ctr != predicted_ctr[i_sorted[i]]:
auc_temp += (click_sum+old_click_sum) * no_click / 2.0
old_click_sum = click_sum
no_click = 0.0
last_ctr = predicted_ctr[i_sorted[i]]
no_click += num_impressions[i_sorted[i]] - num_clicks[i_sorted[i]]
no_click_sum += num_impressions[i_sorted[i]] - num_clicks[i_sorted[i]]
click_sum += num_clicks[i_sorted[i]]
auc_temp += (click_sum+old_click_sum) * no_click / 2.0
auc = auc_temp / (click_sum * no_click_sum)
return auc
我对段落“(click_sum+old_click_sum) * no_click / 2.0”的含义感到困惑。请帮帮我。</p>