索引 ndarray - 1 项的存储方式与 >1 不同

Question

我正在使用 genfromtxt 从 txt 文件导入数据。

根据genfromtxt

，此数据被导入到一个 ndarray 中

正常情况下，这个文本文件有很多行数据要导入，也就是说ndarray是这样的：

array([ ('2016-04-17T00:08:42.273000Z', '2016-04-17T00:08:50.595000Z', '2016-04-17T00:08:58.378391Z', '2016-04-17T00:08:58.840273Z', '2016-04-17T00:09:05.670000Z', '2016-04-17T00:09:06.115000Z', '2016-04-17T00:09:07.155000Z', '2016-04-17T00:09:06.804999Z', '2016-04-17T00:09:08.488391Z', '2016-04-17T00:09:14.890273Z', '2016-04-17T00:09:11.648393Z', 1.702756, 10, 3.959),
   ('2016-04-17T01:11:11.393000Z', '2016-04-17T01:11:19.715000Z', '2016-04-17T01:11:27.498391Z', '2016-04-17T01:11:27.960273Z', '2016-04-17T01:11:34.790000Z', '2016-04-17T01:11:35.235000Z', '2016-04-17T01:11:36.275000Z', '2016-04-17T01:11:35.924999Z', '2016-04-17T01:11:37.608391Z', '2016-04-17T01:11:44.010273Z', '2016-04-17T01:11:40.768393Z', 3.084912, 10, 3.423),
   ('2016-05-20T19:10:42.883000Z', '2016-05-20T19:10:51.205000Z', '2016-05-20T19:10:58.978393Z', '2016-05-20T19:10:59.441114Z', '2016-05-20T19:11:06.280000Z', '2016-05-20T19:11:06.705000Z', '2016-05-20T19:11:07.725000Z', '2016-05-20T19:11:07.405000Z', '2016-05-20T19:11:09.108393Z', '2016-05-20T19:11:15.481160Z', '2016-05-20T19:11:12.258393Z', 1.956513, 10, 3.078)], 
  dtype=[('origintime', 'S27'), ('JAMA', 'S27'), ('FLF1', 'S27'), ('MAG1', 'S27'), ('AV18', 'S27'), ('AV21', 'S27'), ('AMA1', 'S27'), ('BV15', 'S27'), ('PPLP', 'S27'), ('HPAL', 'S27'), ('ILLI', 'S27'), ('stackedcorr', '<f8'), ('totalstations', '<i8'), ('magestimate', '<f8')])

但是当文本文件只有一行时，ndarray 是这样的（注意像前面的例子一样没有方括号）：

array(('2016-05-08T03:13:02.841000Z', '2016-05-08T03:13:10.705000Z', '1900-01-01T00:00:00.000000Z', '2016-05-08T03:13:14.099997Z', '2016-05-08T03:13:14.938393Z', '2016-05-08T03:13:29.228391Z', '2016-05-08T03:13:31.868393Z', '2016-05-08T03:13:31.909995Z', '2016-05-08T03:13:36.920000Z', '2016-05-08T03:13:37.080000Z', '2016-05-08T03:13:37.635000Z', 9.0, 9, 3.41), 
  dtype=[('origintime', 'S27'), ('JAMA', 'S27'), ('CABP', 'S27'), ('MAG1', 'S27'), ('FLF1', 'S27'), ('PAC1', 'S27'), ('GGPT', 'S27'), ('PINO', 'S27'), ('SUCR', 'S27'), ('BNAS', 'S27'), ('SLOR', 'S27'), ('stackedcorr', '<f8'), ('totalstations', '<i8'), ('magestimate', '<f8')])

区别是多行输入是数组，单行输入不是。

由于单行输入的可能性，我无法循环遍历 results['origintime'][i]，这搞乱了索引。

如何将单行输入（无方括号）的 ndarray 转换为 len=1 列表，这意味着它与多行 ndarray 具有相同的格式？

谢谢

Answer 1

Numpy 实际上是以数组的形式载入文件，但它是一个“0 维”数组。也就是说，results.ndim 将 return 0。您可以通过 results.reshape((1,)).

将其转换为具有 1 个元素的一维数组

如果你正在读入一个文件，并且你不知道它是一行还是多行，你可以这样做：

results = np.genfromtxt(filename)
if results.ndim==0:
    results.reshape((1,))

索引 ndarray - 1 项的存储方式与 >1 不同

Indexing a ndarray - 1 item is stored differently to >1

python

indexing

multidimensional-array

genfromtxt