Pandas - Reading CSV file with variable number of columns

 If the CSV/ text file has different number of columns along the rows, it will fail reading with simple "pd.read_csv(file)".

Instead of it, try naming the columns. It will read until the number of columns supplied.

For example:

df0=pd.read_csv(filename, sep=';',names=['a', 'b', 'c', 'd', 'e'])

It will read only until 5 columns wide.

Pandas sum column values according to another columns value

One-liner code to sum Pandas second columns according to same values in the first column.

df2 = df1.groupby(df1.columns[0])[df1.columns[1]].sum().reset_index()

For example, applying to a table listing pipe diameters and lenghts, the command will return total lenghts according to each unique diameters.

This functionality is similar to excel's pivot table sum.