pandas 列上的熊猫数据框排序会引发索引上的关键错误
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pandas dataframe sort on column raises keyerror on index
提问by gvoysey
I have the following dataframe, df:
我有以下数据框df：
peaklatency snr
0 52.99 0.0
1 54.15 62.000000
2 54.12 82.000000
3 54.64 52.000000
4 54.57 42.000000
5 54.13 72.000000
I'm attempting to sort this by snr:
我正在尝试按以下方式排序snr：
df.sort_values(df.snr)
but this raises
但这会引起
_convert_to_indexer(self, obj, axis, is_setter)
1208 mask = check == -1
1209 if mask.any():
-> 1210 raise KeyError('%s not in index' % objarr[mask])
1211
1212 return _values_from_object(indexer)
KeyError: '[ inf 62. 82. 52. 42. 72.] not in index'
I am not explicitly setting an index on this DataFrame, it's coming from a list comprehension:
我没有在这个 DataFrame 上明确设置索引，它来自列表理解：
import pandas as pd
d = []
for run in runs:
d.append({
'snr': run.periphery.snr.snr,
'peaklatency': (run.brainstem.wave5.wave5.argmax() / 100e3) * 1e3
})
df = pd.DataFrame(d)
回答by chrisb
The bykeyword to sort_valuesexpects column names, not the actual Series itself. So, you'd want:
该by关键字sort_values预计列名，而不是实际的系列本身。所以，你会想要：
In [23]: df.sort_values('snr')
Out[23]:
peaklatency snr
0 52.99 0.0
4 54.57 42.0
3 54.64 52.0
1 54.15 62.0
5 54.13 72.0
2 54.12 82.0
