Concatenating row, column indexes from a dataframe

Question

I have one dataframe like this with the first column is the index (i.e., index = [1,2,3]):

    1      2      3
1   0      0.43   0.61
2   0.88   0      0.12
3   0.33   0.95   0

The new dataframe should look like the below:

Link      Value
1_1       0
1_2       0.43
1_3       0.61
2_1       0.88
2_2       0
2_3       0.12
3_1       0.33
3_2       0.95
3_3       0

Any help is highly appreciated! Thank you!

Answer 1

Simply do this

import pandas as pd

data = {
    1: [0, 0.43, 0.61],
    2: [0.88, 0, 0.12],
    3: [0.33, 0.95, 0]
}
index = [1, 2, 3]
df = pd.DataFrame(data, index=index)

df_melted = df.reset_index().melt(id_vars='index', var_name='Column', value_name='Value')
df_melted['Link'] = df_melted['index'].astype(str) + '_' + df_melted['Column'].astype(str)
df_result = df_melted[['Link', 'Value']]


df_result

which gives

 Link  Value
0  1_1   0.00
1  2_1   0.43
2  3_1   0.61
3  1_2   0.88
4  2_2   0.00
5  3_2   0.12
6  1_3   0.33
7  2_3   0.95
8  3_3   0.00