我嘗試了以下陳述：import pandas as pddf = pd.DataFrame(index=[i for i in range(5)])df.columns = ["res"+str(i) for i in range(5)]Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Python35\lib\site-packages\pandas\core\generic.py", line 5080, in __setattr__ return object.__setattr__(self, name, value) File "pandas\_libs\properties.pyx", line 69, in pandas._libs.properties.AxisProperty.__set__ File "C:\Python35\lib\site-packages\pandas\core\generic.py", line 638, in _set_axis self._data.set_axis(axis, labels) File "C:\Python35\lib\site-packages\pandas\core\internals\managers.py", line 155, in set_axis 'values have {new} elements'.format(old=old_len, new=new_len))ValueError: Length mismatch: Expected axis has 0 elements, new values have 5 elements不明白這是什么原因。如果我有索引，那么為什么沒有添加該列？
2 回答
POPMUISE
TA貢獻1765條經驗 獲得超5個贊
我認為問題首先是沒有創建列DataFrame，所以如果要分配列名它失敗了。
解決方案是將參數添加columns到 DataFrame 構造函數，索引應簡化 - 僅分配range：
df = pd.DataFrame(index= range(5), columns=["res"+str(i) for i in range(5)])
print (df)
res0 res1 res2 res3 res4
0 NaN NaN NaN NaN NaN
1 NaN NaN NaN NaN NaN
2 NaN NaN NaN NaN NaN
3 NaN NaN NaN NaN NaN
4 NaN NaN NaN NaN NaN
如果想在只有索引的 DataFrame 之后分配，可以使用DataFrame.reindex：
df = pd.DataFrame(index=range(5))
df = df.reindex(["res"+str(i) for i in range(5)], axis=1)
print (df)
res0 res1 res2 res3 res4
0 NaN NaN NaN NaN NaN
1 NaN NaN NaN NaN NaN
2 NaN NaN NaN NaN NaN
3 NaN NaN NaN NaN NaN
4 NaN NaN NaN NaN NaN
LEATH
TA貢獻1936條經驗 獲得超7個贊
import pandas as pd
df = pd.DataFrame(index= range(5))
for i in range(5):
df['res'+str(i)]= '0'
print (df)
res0 res1 res2 res3 res4
0 0 0 0 0 0
1 0 0 0 0 0
2 0 0 0 0 0
3 0 0 0 0 0
4 0 0 0 0 0
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