Can I name 2 subsequent columns identical like the previous one? (python)-CodePudding

I have a dataset in Excel and some columns are unnamed there: A_ColumnWithName, Unnamed1, Unnamed2, B_ColumnWithName, Unnamed3, Unnamed4

I need to set the names of the currently unnamed columns to the same as the 1st column name from the left, so my columns should look like this:

A_ColumnWithName, A_ColumnWithName, A_ColumnWithName, B_ColumnWithName, B_ColumnWithName, B_ColumnWithName

Any hints how can I do it using Python? An important thing is that there is tons of such columns that's why it's required to do in the most automatic way possible.

CodePudding user response：

You can convert the index to Series and use it to mask the names that contain "Unnamed" and ffill the previous valid name:

cols = df.columns.to_series()
df.columns = cols.mask(cols.str.contains('Unnamed')).ffill()

Note however that having duplicated columns names is not encouraged

example input:

   A Unnamed1 Unnamed2  B Unnamed3  C
0  x        x        x  x        x  x

output:

   A  A  A  B  B  C
0  x  x  x  x  x  x

CodePudding user response：

The following code would work.

import pandas as pd
df = pd.DataFrame( columns= ["A_ColumnWithName", "unnamed","unnamed", "B_ColumnWithName", "unnamed", "unnamed"])

replaceWith = df.columns.values[0]
for i in range(1, len(df.columns)):
    if df.columns[i] == 'unnamed':
        df.columns.values[i] = replaceWith
    else:
        replaceWith = df.columns.values[i]