python multiindex assignment

Question

I have an issue with multiindex assignment and will like to store values as highlighted below

I have a function called df_x that is a dataframe and looks like

print df_x

serial    P1       P2       P3

5         21       32       35
10        33       45       76
15        65       99       563

I will like it to store as follows

For example for level[0] of value alpha

df1 = pd.DataFrame(columns= df_x.columns)

it should create a multiindex on df1 so that

print df1 should look like

print df1


alpha    serial    5     10    15

         P1        21    33    65

         P2        32    45    99

         P3        35    76    563

However, I am struggling to create multiindex on original df_x dataframe

Any help will be highly appreciated.

piRSquared · Accepted Answer · 2017-08-01 20:39:58Z

1

Option 0

pd.concat([df_x], keys=['alpha'])

serial    P1  P2   P3
alpha 5   21  32   35
      10  33  45   76
      15  65  99  563

Option 1

pd.DataFrame(
    df_x.values,
    [['alpha'] * len(df_x), df_x.index],
    df_x.columns
)

serial    P1  P2   P3
alpha 5   21  32   35
      10  33  45   76
      15  65  99  563

Option 2

df_x.set_index(
    pd.MultiIndex.from_product(
        [['alpha'], df_x.index], names=[None, df_x.index.name]
    )
)

Setup

df_x = pd.DataFrame(**{
    'columns': pd.Index(['P1', 'P2', 'P3'], name='serial'),
    'data': [[21, 32, 35], [33, 45, 76], [65, 99, 563]],
    'index': [5, 10, 15]})

edited Aug 1, 2017 at 20:39

answered Aug 1, 2017 at 20:33

piRSquared

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1 Comment

piRSquared Over a year ago

Thank you. I appreciate that.

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