Python中asarray用法

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通过在编译环境中输入

import numpyhelp(numpy.asarray)

Help on function asarray in module numpy.core.numeric:

asarray(a, dtype=None, order=None)
Convert the input to an array.

Parameters
----------
a : array_like
Input data, in any form that can be converted to an array. This
includes lists, lists of tuples, tuples, tuples of tuples, tuples
of lists and ndarrays.
dtype : data-type, optional
By default, the data-type is inferred from the input data.
order : {'C', 'F'}, optional
Whether to use row-major ('C') or column-major ('F' for FORTRAN)
memory representation. Defaults to 'C'.

举例：

Convert a list into an array:将列表转换为数组

>>> a = [1,2]>>> numpy.asarray(a)array([1, 2])

将数据类型转换为float和int

>>> a= [1,2]>>> numpy.asarray(a,'f')array([ 1.,  2.], dtype=float32)>>> numpy.asarray(a,'i')array([1, 2])

判断a中数是否大于0，如果大于0，则将该数置为1,

>>> a = [[1,2],[1,0]]>>> a = numpy.asarray(a) #必须先转换为array，否则出现array(1.0, dtype=float32)>>> numpy.asarray(a>0,'i') #'i'表示为dtype类型为intarray([[1, 1],       [1, 0]])>>> numpy.asarray(a>0,'f')array([[ 1.,  1.],       [ 1.,  0.]], dtype=float32)

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