如何将索引转换为列表?

问题描述

我的索引:

Index([u'Newal', u'Saraswati Khera', u'Tohana'], dtype='object')

我必须将此格式转换为以下格式的列表:

I have to convert this format into list with following format:

['Newal','SaraswatiKhera','Tohana']

推荐答案

您可以使用 tolist 或list:

print df.index.tolist()

print list(df.index)

但是最快的解决方案是通过 values tolist (感谢 EdChum )

But the fastest solution is convert np.arry by values tolist (thanks EdChum)

print df.index.values.tolist()

示例:

import pandas as pd

idx = pd.Index([u'Newal', u'Saraswati Khera', u'Tohana'])
print idx
Index([u'Newal', u'Saraswati Khera', u'Tohana'], dtype='object')

print idx.tolist()
[u'Newal', u'Saraswati Khera', u'Tohana']

print list(idx)
[u'Newal', u'Saraswati Khera', u'Tohana']

如果您需要编码UTF-8:

print [x.encode('UTF8') for x in idx.tolist()]
['Newal', 'Saraswati Khera', 'Tohana']

另一种解决方案:

print [str(x) for x in idx.tolist()]
['Newal', 'Saraswati Khera', 'Tohana']

，但是如果unicode字符串字符不在ASCII范围内，则会失败.

but it would fail if the unicode string characters do not lie in the ascii range.

时间:

import pandas as pd
import numpy as np

#random dataframe
np.random.seed(1)
df = pd.DataFrame(np.random.randint(10, size=(3,3)))
df.columns = list('ABC')
df.index = [u'Newal', u'Saraswati Khera', u'Tohana']
print df

print df.index
Index([u'Newal', u'Saraswati Khera', u'Tohana'], dtype='object')

print df.index.tolist()
[u'Newal', u'Saraswati Khera', u'Tohana']

print list(df.index)
[u'Newal', u'Saraswati Khera', u'Tohana']

print df.index.values.tolist()
[u'Newal', u'Saraswati Khera', u'Tohana']


In [90]: %timeit list(df.index)
The slowest run took 37.42 times longer than the fastest. This could mean that an intermediate result is being cached
100000 loops, best of 3: 2.18 µs per loop

In [91]: %timeit df.index.tolist()
The slowest run took 22.33 times longer than the fastest. This could mean that an intermediate result is being cached
1000000 loops, best of 3: 1.75 µs per loop

In [92]: %timeit df.index.values.tolist()
The slowest run took 62.72 times longer than the fastest. This could mean that an intermediate result is being cached
1000000 loops, best of 3: 787 ns per loop

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