[pandas Columns or Index] add new level #python #pandas #columns #index #add #level #multilevel

snippet.py

# pandas stuff

```python
 #add a level in the columns below all current ones
df.columns = pd.MultiIndex.from_product([df.columns, ['C']])
```



```python
# enter it in between
df.columns = pd.MultiIndex.from_tuples(\
                       map(lambda x: (x[0], 'A', *x[1:]), df.columns))
```


```
# test for the above:
import pandas as pd
df = pd.DataFrame({"col1":[2,3,5],"col2":["abc","cdef","sdgae"]})
display(df)
df.columns = pd.MultiIndex.from_product([df.columns, ['C']])
display(df)
df.columns = pd.MultiIndex.from_tuples(\
                       map(lambda x: (x[0], 'A', *x[1:]), df.columns))
display(df)