Comparison of matrices and arrays in NUMpy
Array can realize all functions of matrix, but it is easier to operate matrix in realizing some functions, for example, matrix multiplication directly uses A*B instead of functions, but array can deal with various data more flexibly, and can represent high-dimensional array with faster speed
numpy.matrix
Create a matrix
Matrix (string/list/tuple/array) mat (string/list/tuple/array)
a= np.matrix('1 2 3; 4, 5 6 ')
b = np.mat([
[1.2.3],
[4.5.6]])print(a)
print(type(a))
print(b)
print(type(b))
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c = np.array([
[1.2.3],
[4.5.6]
])
d = np.mat(c)
print(d)
print(type(c))
print(type(d))
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Properties of a matrix object
attribute | instructions |
---|---|
.dim | The dimension of the matrix |
.shape | Shape of matrix |
.size | The number of elements in the matrix |
.dtype | The data type of the element |
print(d)
print(d.ndim)
print(d.shape)
print(d.size)
print(d.dtype)
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Matrix operations
Matrix multiplication
m1 = np.mat([
[0.1],
[2.3]
])
m2 = np.mat([
[1.1],
[2.0]])print(m1*m2)
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Matrix transpose
Matrix transpose:.t
Inverse matrix
Matrix inverse:.i
m = np.mat([
[0.1],
[2.3]])print(m.T)
print(m.I)
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