python - 使用 numpy loadtxt 将导入字符串转换为 float

Question

我正在尝试从平面文件导入文本并将其转换为单行内的浮点值。我见过this post它有相同的错误，但我还没有找到输入文件中哪些字符无效。或者我有语法错误？

作为字符串导入并打印结果:

data = np.loadtxt(file, delimiter='\t', dtype=str)
print(data[0:2])
... 
[["b'Time'" "b'Percent'"]
 ["b'99'" "b'0.067'"]]

尝试导入为 float :

# Import data as floats and skip the first row: data_float
data_float = np.loadtxt(data, delimiter='\t', dtype=float, skiprows=1)

它抛出以下错误:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
    data_float = np.loadtxt(data, delimiter='\t', dtype=float, skiprows=1)
  File "<stdin>", line 848, in loadtxt
    items = [conv(val) for (conv, val) in zip(converters, vals)]
  File "<stdin>", line 848, in <listcomp>
    items = [conv(val) for (conv, val) in zip(converters, vals)]
ValueError: could not convert string to float: b'["b\'99\'" "b\'0.067\'"]'

对了，我也看过this post这解释了 b 字符，但我认为这不是问题所在。

第一个答案建议的附加故障排除步骤:

data = np.loadtxt(file, delimiter="\tb'", dtype=str)

返回:

array(["b'Time\\tPercent'", "b'99\\t0.067'", "b'99\\t0.133'",
       "b'99\\t0.067'", "b'99\\t0'", "b'99\\t0'", "b'0\\t0.5'",
       "b'0\\t0.467'", "b'0\\t0.857'", "b'0\\t0.5'", "b'0\\t0.357'",
       "b'0\\t0.533'", "b'5\\t0.467'", "b'5\\t0.467'", "b'5\\t0.125'",
       "b'5\\t0.4'", "b'5\\t0.214'", "b'5\\t0.4'", "b'10\\t0.067'",
       "b'10\\t0.067'", "b'10\\t0.333'", "b'10\\t0.333'", "b'10\\t0.133'",
       "b'10\\t0.133'", "b'15\\t0.267'", "b'15\\t0.286'", "b'15\\t0.333'",
       "b'15\\t0.214'", "b'15\\t0'", "b'15\\t0'", "b'20\\t0.267'",
       "b'20\\t0.2'", "b'20\\t0.267'", "b'20\\t0.437'", "b'20\\t0.077'",
       "b'20\\t0.067'", "b'25\\t0.133'", "b'25\\t0.267'", "b'25\\t0.412'",
       "b'25\\t0'", "b'25\\t0.067'", "b'25\\t0.133'", "b'30\\t0'",
       "b'30\\t0.071'", "b'30\\t0'", "b'30\\t0.067'", "b'30\\t0.067'",
       "b'30\\t0.133'"], 
      dtype='<U16')

Answer 1

感谢所有看我问题的人。我重新启动了 IPython，现在可以毫无问题地执行相同的代码。这是与上面相同的有效代码。

data_float = np.loadtxt(file, delimiter='\t', dtype=float, skiprows=1)

结果:

In [1]: data_float
Out[1]: 
array([[  9.90000000e+01,   6.70000000e-02],
       [  9.90000000e+01,   1.33000000e-01],
       [  9.90000000e+01,   6.70000000e-02],
       [  9.90000000e+01,   0.00000000e+00],
       [  9.90000000e+01,   0.00000000e+00],
       [  0.00000000e+00,   5.00000000e-01],
       [  0.00000000e+00,   4.67000000e-01],
       [  0.00000000e+00,   8.57000000e-01],
       [  0.00000000e+00,   5.00000000e-01],
       [  0.00000000e+00,   3.57000000e-01],
       [  0.00000000e+00,   5.33000000e-01],
       [  5.00000000e+00,   4.67000000e-01],
       [  5.00000000e+00,   4.67000000e-01],
       [  5.00000000e+00,   1.25000000e-01],
       [  5.00000000e+00,   4.00000000e-01],
       [  5.00000000e+00,   2.14000000e-01],
       [  5.00000000e+00,   4.00000000e-01],
       [  1.00000000e+01,   6.70000000e-02],
       [  1.00000000e+01,   6.70000000e-02],
       [  1.00000000e+01,   3.33000000e-01],
       [  1.00000000e+01,   3.33000000e-01],
       [  1.00000000e+01,   1.33000000e-01],
       [  1.00000000e+01,   1.33000000e-01],
       [  1.50000000e+01,   2.67000000e-01],
       [  1.50000000e+01,   2.86000000e-01],
       [  1.50000000e+01,   3.33000000e-01],
       [  1.50000000e+01,   2.14000000e-01],
       [  1.50000000e+01,   0.00000000e+00],
       [  1.50000000e+01,   0.00000000e+00],
       [  2.00000000e+01,   2.67000000e-01],
       [  2.00000000e+01,   2.00000000e-01],
       [  2.00000000e+01,   2.67000000e-01],
       [  2.00000000e+01,   4.37000000e-01],
       [  2.00000000e+01,   7.70000000e-02],
       [  2.00000000e+01,   6.70000000e-02],
       [  2.50000000e+01,   1.33000000e-01],
       [  2.50000000e+01,   2.67000000e-01],
       [  2.50000000e+01,   4.12000000e-01],
       [  2.50000000e+01,   0.00000000e+00],
       [  2.50000000e+01,   6.70000000e-02],
       [  2.50000000e+01,   1.33000000e-01],
       [  3.00000000e+01,   0.00000000e+00],
       [  3.00000000e+01,   7.10000000e-02],
       [  3.00000000e+01,   0.00000000e+00],
       [  3.00000000e+01,   6.70000000e-02],
       [  3.00000000e+01,   6.70000000e-02],
       [  3.00000000e+01,   1.33000000e-01]])