Python/Pandas: Sort dataframe columns based on a column name

Question

I have a dataframe containing several columns labelled x1, x2, x3, and x4.

Depending on the analysis, I would need to assign one of the four columns to be the first column when ordering the four columns in the dataframe from left-to-right.

For instance, if I want column 'x2' to be the first I assign it to 'sorter'.

sorter = x2

Now my question: how I sort the dataframes in the column so that the column assigned to 'sorter' is located in the first column?

EDIT: The order of the rest of the columns should remain unchanged.

isn't this function what you want to use? pandas.pydata.org/pandas-docs/stable/reference/api/… — fulaphex
– fulaphex, Commented Mar 1, 2021 at 19:35
and you can use that to swap the columns of your dataframe stackoverflow.com/a/25652061/5228292 — fulaphex
– fulaphex, Commented Mar 1, 2021 at 19:37
if you don't specify the other columns, it won't sort them. I'm not sure if it uses a stable sorting algorithm, so the order in the rest of the columns might be random — fulaphex
– fulaphex, Commented Mar 1, 2021 at 19:39

Inputvector · Accepted Answer · 2021-03-01 20:40:29Z

2

You can change order of columns like:

data = {'X1':  ['11', '12'],
        'X2': ['21', '22'],
        'X3': ['31', '32']
        }

df = pd.DataFrame(data)
df
    X1  X2  X3
0   11  21  31
1   12  22  32

df = df.reindex(['X3','X1','X2'], axis=1)
df

    X3  X1  X2
0   31  11  21
1   32  12  22

Note : You need to provide desired order.

You can create a function to change order by given column:

def sorter(desired, df):
    columns = df.columns.tolist()
    columns.remove(desired)
    columns.insert(0,desired)
    return df.reindex(columns, axis=1)

sorter('X2',df)

    X2  X1  X3
0   21  11  31
1   22  12  32

edited Mar 1, 2021 at 20:40

answered Mar 1, 2021 at 19:44

Inputvector

1,09310 silver badges22 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

StatsScared Over a year ago

Thank you. Is there a way to assign the column that I want as 'first column' to a variable (like in my post) and have the order of the rest of the columns remain unchanged?

Inputvector Over a year ago

Hope the sorter function helps. It change first column as given and keep rest of them the same.

Collectives™ on Stack Overflow

Python/Pandas: Sort dataframe columns based on a column name

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related