*Result*: A Storage and Classification Algorithm for Concept Drift Data Streams Based on OS-ELM.

*Many methods can deal with some special cases of data streams (e.g., concept drift) currently; however, these methods need to store historical data and access them repeatedly, which is inconsistent with the single-channel characteristics of data streams, and it requires a large amount of memory space to save data when very slow gradual drift occurs due to the infinite feature of data streams. To address this problem, this paper proposes a concept drift data stream storage and classification algorithm based on OS-ELM (SC-OS-ELM), which uses a matrix of fixed size to save the feature information of historical data, and retrains the classifier by accessing this feature matrix when needed. It achieves the goal of improving the classification accuracy while storing the feature information of historical data in a small and constant memory space. It can help algorithms such as the DDM to solve the data storage problem, making it more applicable. Comparative experimental results on 15 artificial and real data streams validate the effectiveness of SC-OS-ELM, with a significant reduction in the amount of memory space required. [ABSTRACT FROM AUTHOR]*