Abstract: The present disclosure provides a method, apparatus, medium and device for extracting a river drying-up region and frequency, and belongs to the technical field of remote sensing. The method for extracting a river drying-up region and frequency can be applied to efficiently acquiring river drying-up information for a long time within the large spatial region. With the inverse normalized difference water index (iNDWI) and the maximum value composite (MVC) method for the remote sensing images, the present disclosure omits the troublesome step of separately extracting a river range for each image in the conventional method. In addition, the present disclosure quickly obtains the drying-up frequency by counting the total number of available images and the number of non-water images at the same pixel position, and yields a greater efficiency for extracting the river drying-up region and frequency.

Abstract: Evaluating credibility of an online trading user includes, based on a user to be evaluated, querying reference users corresponding to the user to be evaluated. The reference users include trading users who have conducted a transaction with the user to be evaluated and may be obtained from a referenced transaction record of the user to be evaluated. Property information of the reference users may be obtained, and a credibility evaluation result for the user to be evaluated may be generated based on the property information of the reference users and a proportion of all transactions conducted between the user to be evaluated and the reference users for which sales transactions account.