how do I insert a column at a specific column index in pandas? how do I insert a column at a specific column index in pandas? python python

how do I insert a column at a specific column index in pandas?


see docs: http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.insert.html

using loc = 0 will insert at the beginning

df.insert(loc, column, value)

df = pd.DataFrame({'B': [1, 2, 3], 'C': [4, 5, 6]})dfOut:    B  C0  1  41  2  52  3  6idx = 0new_col = [7, 8, 9]  # can be a list, a Series, an array or a scalar   df.insert(loc=idx, column='A', value=new_col)dfOut:    A  B  C0  7  1  41  8  2  52  9  3  6


If you want a single value for all rows:

df.insert(0,'name_of_column','')df['name_of_column'] = value

Edit:

You can also:

df.insert(0,'name_of_column',value)


You could try to extract columns as list, massage this as you want, and reindex your dataframe:

>>> cols = df.columns.tolist()>>> cols = [cols[-1]]+cols[:-1] # or whatever change you need>>> df.reindex(columns=cols)   n  l  v0  0  a  11  0  b  22  0  c  13  0  d  2

EDIT: this can be done in one line ; however, this looks a bit ugly. Maybe some cleaner proposal may come...

>>> df.reindex(columns=['n']+df.columns[:-1].tolist())   n  l  v0  0  a  11  0  b  22  0  c  13  0  d  2


matomo