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### python - i can't figure out how to represent a numpy matrix

I want to understand an array for dot product calculation using numpy in python

A = numpy.array (([1,2], [3,4], [5,6]]) two-dimensional array
B = numpy.array ([[1,2]]) 2D array
C = numpy.array ([3,4]) 1D array

A.shape
>>>(3,2)
B.shape
>>>(1,2)
C.shape
>>>(2,)

Error message

Although A can be understood up to 3 rows and 2 columns and B can be understood up to 1 rows and 2 columns,
I don't know why C is 2 lines.
When examined, one-dimensional arrays are numbers arranged side by side.
(1,) I thought it would be one line.

In this regard, you need to understand concepts such as ndim, shape and axis. Please refer to the appropriate article.

What does NumPy's axis and dimension number (ndim) mean?-DeepAge

Other miscellaneous things.

C in the question sentence is not called "2 lines". Usually called a one-dimensional array with two elements

shape numbers do not correspond to rows or columns. In 2D, for convenience, axis 0 is sometimes referred to as row and 1 as column.

The 1D and 2D arrays are not related to the vector dimensions. Rather, it may be better to think of it as a tensor, but it is not so expensive because it is a data structure. If it's a mess, it's the number of subscripts.