Numpy learning

One 、 What is? Numpy

NumPy  It's a very fast math library , Mainly used for array calculation , contain ：
1. A powerful N Dimensional array object  ndarray.
2. Broadcast function .
3. Integrate  C/C++/Fortran  Code tools .
4. linear algebra 、 The Fourier transform 、 Random number generation and other functions .

Two 、Numpy Ndarray object

1.NumPy  One of the most important features is its  N  Dimensional array object  ndarray, It is a series of data of the same type （ It can store ） Set , With  0  The subscript is to start indexing the elements in the collection .
2.ndarray  Object is a multidimensional array used to hold elements of the same type .
3.ndarray  Each element in has an area of the same storage size in memory .
4.ndarray  The interior consists of ：
· A point to data （ A piece of data in a memory or memory mapped file ） The pointer to .
· Data type or  dtype, A cell that describes a fixed size value in an array .
· An array shape （shape） tuples , A tuple representing the size of each dimension .
· A span tuple （stride）, The integer refers to the need to move forward to the next element of the current dimension " Across " Bytes of .

 About strides The understanding of the ：
 Reprint ：https://blog.csdn.net/wxfighting/article/details/122758553