pandas melt dataframe according to time index

Question

I have the following dataframe that I try to 'melt'.

So my aim is to get a output with 2 column

So my output should look like [that's only the head of the output, I don't show it fully to be concise]

I have tried the following but it not works.

df2 = pd.melt(df, id_vars=df.index, var_name="Name", value_name="Value")

It says: KeyError: "The following 'id_vars' are not present in the DataFrame:

PS: The columns are 'predictors' so if not too complicated I would be happy to add a P as prexix in the column name like P0 P1 P2 P3 P4 P5

pd.melt(df.reset_index(), id_vars='index', var_name="Name", value_name="Value") — BENY, Aug 13 '19 at 18:20
Perfect, I was not aware of the reset_index. Can you put it as answer? — S12000, Aug 13 '19 at 18:31

score 6 · Accepted Answer · answered Aug 13 '19 at 18:34

6

We can just adding the reset_index

pd.melt(df.reset_index(), id_vars='index', var_name="Name", value_name="Value")

Or using stack

df.stack().reset_index()

answered Aug 13 '19 at 18:34

BENY

1

Note that if your index happens to have a name, you'll have to use that instead of `'index'`. – adr Mar 13 '20 at 14:19

1 Answers1