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俞大猷一张脸几乎扭到了一起。(This picture is really casual. I don't know where the characters were picked out.)Public Object next () {Use Python for data analysis: This book is a detailed version of Python's pandas package. Learn this to master some basic pandas commands. However, this is not the point, because pandas is too slow to produce a large amount of data and may collapse (I don't know if there is any improvement now-!) The point is, through studying this book, I feel a little about the data operation and am familiar with the basic data operation process. All the operations in this book can be replaced by native Python, and Pandas package is not needed. Finding feelings is very important.Avoid coupling the sender and receiver of the request, make it possible for multiple objects to receive the request, connect these objects into a chain, and pass the request along this chain until an object processes it. This is the responsibility chain mode. In the responsibility chain mode, it is possible for each object to process the request, thus realizing decoupling between the sender and receiver of the request. At the same time, the responsibility chain mode simplifies the structure of the object, which makes each object only need to refer to its successor without knowing the whole chain, thus improving the flexibility of the system and making it more convenient to add new request processing classes. However, we cannot guarantee that all requests can be processed in the responsibility chain, and it is not conducive to observing runtime characteristics.Lower mounting