写入文件时numpy数组更改为字符串 [英] numpy array changes to string when writing to file

问题描述

我有一个数据框，其中的一列是一个numpy数组:

I have a dataframe where one of the columns is a numpy array:

 DF

      Name                     Vec
 0  Abenakiite-(Ce) [0.0, 0.0, 0.0, 0.0, 0.0, 0.043, 0.0, 0.478, 0...
 1  Abernathyite    [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, ...
 2  Abhurite        [0.176, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.235, 0...
 3  Abswurmbachite  [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.25, 0.0,...

当我检查每个元素的数据类型时，将返回正确的数据类型.

When I check the data type of each element, the correct data type is returned.

 type(DF['Vec'].iloc[1])
 numpy.ndarray

我将其保存到一个csv文件中:

I save this into a csv file:

DF.to_csv('.\\file.csv',sep='\t')

现在，当我再次读取文件时，

Now, when I read the file again,

new_DF=pd.read_csv('.\\file.csv',sep='\t')

并检查索引1处的Vec数据类型:

and check the datatype of Vec at index 1:

type(new_DF['Vec'].iloc[1])   
str

numpy数组的大小为1x127.

The size of the numpy array is 1x127.

数据类型已从numpy数组更改为字符串.我还可以在各个向量中看到一些新的线元素.我认为这可能是由于将向量写入csv时出现的一些问题，但我不知道如何解决.有人可以帮忙吗?

The data type has changed from a numpy array to a string. I can also see some new line elements in the individual vectors. I think this might be due to some problem when the vector is written into a csv but I don't know how to fix it. Can someone please help?

谢谢！

推荐答案

在注释中，我犯了一个错误，并说dtype而不是converters.您想要的是在阅读功能时将其转换.有一些虚拟变量:

In the comments I made a mistake and said dtype instead of converters. What you want is to convert them as you read them using a function. With some dummy variables:

df=pd.DataFrame({'name':['name1','name2'],'Vec':[np.array([1,2]),np.array([3,4])]})
df.to_csv('tmp.csv')
def converter(instr):
    return np.fromstring(instr[1:-1],sep=' ')
df1=pd.read_csv('tmp.csv',converters={'Vec':converter})
df1.iloc[0,2]
array([1., 2.])

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