python - 从 numpy 结构化数组(数组中的元组列表)中删除列？

Question

我使用一个外部库函数，它返回一个 numpy 结构化数组。

cities_array
>>> array([ (1, [-122.46818353792992, 48.74387985436505], u'05280', u'Bellingham', u'53', u'Washington', u'5305280', u'city', u'N', -99, 52179),
       (2, [-109.67985528815007, 48.54381826401885], u'35050', u'Havre', u'30', u'Montana', u'3035050', u'city', u'N', 2494, 10201),
       (3, [-122.63068540357023, 48.49221584868184], u'01990', u'Anacortes', u'53', u'Washington', u'5301990', u'city', u'N', -99, 11451),
       ...,
       (3147, [-156.45657614262274, 20.870633142444376], u'22700', u'Kahului', u'15', u'Hawaii', u'1522700', u'census designated place', u'N', 7, 16889),
       (3148, [-156.45038252004554, 20.76059218396], u'36500', u'Kihei', u'15', u'Hawaii', u'1536500', u'census designated place', u'N', -99, 11107),
       (3149, [-155.08472452266503, 19.693112205773275], u'14650', u'Hilo', u'15', u'Hawaii', u'1514650', u'census designated place', u'N', 38, 37808)], 
      dtype=[('ID', '<i4'), ('Shape', '<f8', (2,)), ('CITY_FIPS', '<U5'), ('CITY_NAME', '<U40'), ('STATE_FIPS', '<U2'), ('STATE_NAME', '<U25'), ('STATE_CITY', '<U7'), ('TYPE', '<U25'), ('CAPITAL', '<U1'), ('ELEVATION', '<i4'), ('POP1990', '<i4')])

cities_array 的类型为 <type 'numpy.ndarray'> 。

我能够访问数组的各个列:

cities_array[['ID','CITY_NAME']]
>>> array([(1, u'Bellingham'), (2, u'Havre'), (3, u'Anacortes'), ...,
       (3147, u'Kahului'), (3148, u'Kihei'), (3149, u'Hilo')], 
      dtype=[('ID', '<i4'), ('CITY_NAME', '<U40')])

现在我想删除第一列 ID 。 help 和 SO questions 说它应该是 numpy.delete 。

运行此命令时:numpy.delete(cities_array,cities_array['ID'],1) 我收到错误消息:

...in delete
    N = arr.shape[axis]
IndexError: tuple index out of range

我做错了什么？我应该对city_array进行后处理以便能够使用该数组吗？

我使用的是 Python 2.7.10 和 numpy 1.11.0

Answer 1

我认为这应该有效:

def delete_colum(array, *args):

    filtered = [x for x in array.dtype.names if x not in args]

    return array[filtered]

数组示例:

a
Out[9]: 
array([(1, [-122.46818353792992, 48.74387985436505])], 
      dtype=[('ID', '<i4'), ('Shape', '<f8', (2,))])

delete_colum(a,'ID')
Out[11]: 
array([([-122.46818353792992, 48.74387985436505],)], 
      dtype=[('Shape', '<f8', (2,))])