如何访问numpy recarray的第k个字段？

Question

我可以创建一个可记录数组(recarray)，并通过名称访问它的成员:

import numpy as np

n = 20
x = np.recarray((n,), dtype=[('x',int),('y',float),('label',object)])
x.x[:] = range(n)
x.y[:] = np.arange(n)*0.08
x.label[:] =  ['%d bottles of beer on the wall' % i for i in range(n)]

我可以通过行索引访问数据，或者遍历行：

>>> print x[3]
(3, 0.24, '3 bottles of beer on the wall')

但是我怎么迭代记录数组中的字段或获取第k个字段呢？

- Jason S

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嗯。我想我会从numpy.recarray转换为pandas.DataFrame。 - Jason S

Answer 1

recarray具有field()方法，可用于此目的。使用您的示例...

>>> x.field(2)
... array(['0 bottles of beer on the wall', '1 bottles of beer on the wall',
       '2 bottles of beer on the wall', '3 bottles of beer on the wall',
       '4 bottles of beer on the wall', '5 bottles of beer on the wall',
       '6 bottles of beer on the wall', '7 bottles of beer on the wall',
       '8 bottles of beer on the wall', '9 bottles of beer on the wall',
       '10 bottles of beer on the wall', '11 bottles of beer on the wall',
       '12 bottles of beer on the wall', '13 bottles of beer on the wall',
       '14 bottles of beer on the wall', '15 bottles of beer on the wall',
       '16 bottles of beer on the wall', '17 bottles of beer on the wall',
       '18 bottles of beer on the wall', '19 bottles of beer on the wall'], dtype=object)

- JaminSore

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啊哈，谢谢！文档是空的。http://docs.scipy.org/doc/numpy/reference/generated/numpy.recarray.field.html - Jason S