Python 如何将字符串数组转换为 numpy 中的浮点数数组？
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How to convert an array of strings to an array of floats in numpy?
提问by Meh
How to convert
如何转换
["1.1", "2.2", "3.2"]
to
到
[1.1, 2.2, 3.2]
in NumPy?
在 NumPy 中？
采纳答案by Joe Kington
Well, if you're reading the data in as a list, just do np.array(map(float, list_of_strings))(or equivalently, use a list comprehension). (In Python 3, you'll need to call liston the mapreturn value if you use map, since mapreturns an iterator now.)
好吧，如果您将数据作为列表读取，只需执行np.array(map(float, list_of_strings))（或等效地，使用列表理解）。（在Python 3，你需要调用list的map，如果你使用的返回值map，因为map现在返回一个迭代器）。
However, if it's already a numpy array of strings, there's a better way. Use astype().
但是，如果它已经是一个 numpy 字符串数组，那么还有更好的方法。使用astype().
import numpy as np
x = np.array(['1.1', '2.2', '3.3'])
y = x.astype(np.float)
回答by pradeep bisht
You can use this as well
你也可以使用这个
import numpy as np
x=np.array(['1.1', '2.2', '3.3'])
x=np.asfarray(x,float)
回答by Thomio
If you have (or create) a single string, you can use np.fromstring:
如果您有（或创建）单个字符串，则可以使用np.fromstring：
import numpy as np
x = ["1.1", "2.2", "3.2"]
x = ','.join(x)
x = np.fromstring( x, dtype=np.float, sep=',' )
Note, x = ','.join(x)transforms the x array to string '1.1, 2.2, 3.2'. If you read a line from a txt file, each line will be already a string.
注意，x = ','.join(x)将 x 数组转换为 string '1.1, 2.2, 3.2'。如果您从 txt 文件中读取一行，则每一行都将是一个字符串。
回答by Herpes Free Engineer
Another option might be numpy.asarray:
另一种选择可能是numpy.asarray：
import numpy as np
a = ["1.1", "2.2", "3.2"]
b = np.asarray(a, dtype=np.float64, order='C')
For Python 2*:
对于 Python 2*：
print a, type(a), type(a[0])
print b, type(b), type(b[0])
resulting in:
导致：
['1.1', '2.2', '3.2'] <type 'list'> <type 'str'>
[1.1 2.2 3.2] <type 'numpy.ndarray'> <type 'numpy.float64'>
