python - 错误 : object of type 'zip' has no len() after adding extra header by using zip

Question

I try to follow this link pandas dataframe with 2-rows header and export to csv in order for me to created extra header without remove the original header, below is my coding:

df.columns = pd.MultiIndex.from_tuples((zip(df.columns,[uniquevaluesfirstcolumnww, '', uniquevaluesfirstcolumnww1, ' ',uniquevaluesfirstcolumnww2, '  '])))

I get the error such as this: object of type 'zip' has no len()

Anyone have any idea? even though I try to add list before zip but fail also.

Answer 1

我认为问题是 zip 在 python 3 中返回 object，因此需要转换为 list:

df.columns = pd.MultiIndex.from_tuples((list(zip(df.columns,[uniquevaluesfirstcolumnww, '', uniquevaluesfirstcolumnww1, ' ',uniquevaluesfirstcolumnww2, '  ']))))

但是您似乎需要 MultiIndex.from_arrays :

cols = list('abcdef')
df = pd.DataFrame([[1,1,1,1,1,1]], columns=cols)
print (df)
   a  b  c  d  e  f
0  1  1  1  1  1  1

uniquevaluesfirstcolumnww = 'r'
uniquevaluesfirstcolumnww1 = 's'
uniquevaluesfirstcolumnww2 = 't'
vals = [uniquevaluesfirstcolumnww, '', 
        uniquevaluesfirstcolumnww1, ' ',
        uniquevaluesfirstcolumnww2, '  ']
df.columns = pd.MultiIndex.from_arrays([df.columns, vals])
print (df)
   a  b  c  d  e  f
   r     s     t   
0  1  1  1  1  1  1

---

如果列也有 MultiIndex:

cols = pd.MultiIndex.from_product([['a','b','c'], ['x','y']])
df = pd.DataFrame([[1,1,1,1,1,1]], columns=cols)
print (df)
   a     b     c   
   x  y  x  y  x  y
0  1  1  1  1  1  1

uniquevaluesfirstcolumnww = 'r'
uniquevaluesfirstcolumnww1 = 's'
uniquevaluesfirstcolumnww2 = 't'
vals = [uniquevaluesfirstcolumnww, '', 
        uniquevaluesfirstcolumnww1, ' ',
        uniquevaluesfirstcolumnww2, '  ']
df.columns = pd.MultiIndex.from_arrays([df.columns.get_level_values(0), 
                                        df.columns.get_level_values(1), 
                                        vals])
print (df)
   a     b     c   
   x  y  x  y  x  y
   r     s     t   
0  1  1  1  1  1  1