[英]How to convert an array of strings to an array of floats in numpy?
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?
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). 好吧,如果您正在以列表形式读取数据,只需执行
np.array(map(float, list_of_strings))
(或等效地使用列表np.array(map(float, list_of_strings))
)。 (In Python 3, you'll need to call list
on the map
return value if you use map
, since map
returns an iterator now.) (在Python 3中,如果使用
map
,则需要在map
返回值上调用list
,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. 但是,如果它已经是一个numpy字符串数组,那么有一种更好的方法。 Use
astype()
. 使用
astype()
。
import numpy as np
x = np.array(['1.1', '2.2', '3.3'])
y = x.astype(np.float)
You can use this as well 你也可以使用它
import numpy as np
x=np.array(['1.1', '2.2', '3.3'])
x=np.asfarray(x,float)
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'
. 注意,
x = ','.join(x)
将x数组转换为字符串'1.1, 2.2, 3.2'
。 If you read a line from a txt file, each line will be already a string. 如果从txt文件中读取一行,则每行都将是一个字符串。
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'>
You can use np.array()
with dtype = float
:您可以将
np.array()
与 dtype dtype = float
一起使用:
import numpy as np
x = ["1.1", "2.2", "3.2"]
y = np.array(x,dtype=float)
Output: Output:
array([1.1, 2.2, 3.2])
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