Python/Pandas:一系列dict:优化中的数据框 [英] Python/pandas: data frame from series of dict: optimization

问题描述

我有一个pandas系列字典，我想将其转换为具有相同索引的数据框.

I have a pandas Series of dictionnaries, and I want to convert it to a data frame with the same index.

我发现的唯一方法是通过本系列的to_dict方法，该方法效率不高，因为它返回到纯python模式，而不是numpy/pandas/cython.

The only way I found is to pass through the to_dict method of the series, which is not very efficient because it goes back to pure python mode instead of numpy/pandas/cython.

您有更好的建议吗?

非常感谢.

>>> import pandas as pd
>>> flagInfoSeries = pd.Series(({'a': 1, 'b': 2}, {'a': 10, 'b': 20}))
>>> flagInfoSeries
0      {'a': 1, 'b': 2}
1    {'a': 10, 'b': 20}
dtype: object
>>> pd.DataFrame(flagInfoSeries.to_dict()).T
    a   b
0   1   2
1  10  20

推荐答案

我认为您可以使用理解力:

I think you can use comprehension:

import pandas as pd

flagInfoSeries = pd.Series(({'a': 1, 'b': 2}, {'a': 10, 'b': 20}))
print flagInfoSeries
0      {u'a': 1, u'b': 2}
1    {u'a': 10, u'b': 20}
dtype: object

print pd.DataFrame(flagInfoSeries.to_dict()).T
    a   b
0   1   2
1  10  20

print pd.DataFrame([x for x in flagInfoSeries])
    a   b
0   1   2
1  10  20

时间:

In [203]: %timeit pd.DataFrame(flagInfoSeries.to_dict()).T
The slowest run took 4.46 times longer than the fastest. This could mean that an intermediate result is being cached 
1000 loops, best of 3: 554 µs per loop

In [204]: %timeit pd.DataFrame([x for x in flagInfoSeries])
The slowest run took 5.11 times longer than the fastest. This could mean that an intermediate result is being cached 
1000 loops, best of 3: 361 µs per loop

In [209]: %timeit flagInfoSeries.apply(lambda dict: pd.Series(dict))
The slowest run took 4.76 times longer than the fastest. This could mean that an intermediate result is being cached 
1000 loops, best of 3: 751 µs per loop

如果需要保持索引，请尝试将index=flagInfoSeries.index添加到DataFrame构造函数:

If you need keep index, try add index=flagInfoSeries.index to DataFrame constructor:

print pd.DataFrame([x for x in flagInfoSeries], index=flagInfoSeries.index)

时间:

In [257]: %timeit pd.DataFrame([x for x in flagInfoSeries], index=flagInfoSeries.index)
1000 loops, best of 3: 350 µs per loop

示例:

import pandas as pd

flagInfoSeries = pd.Series(({'a': 1, 'b': 2}, {'a': 10, 'b': 20}))
flagInfoSeries.index = [2,8]
print flagInfoSeries
2      {u'a': 1, u'b': 2}
8    {u'a': 10, u'b': 20}

print pd.DataFrame(flagInfoSeries.to_dict()).T
    a   b
2   1   2
8  10  20

print pd.DataFrame([x for x in flagInfoSeries], index=flagInfoSeries.index)
    a   b
2   1   2
8  10  20

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