CODEWITHSUNDEEP
pythonpandasdataframe
Lefteris Kyprianou
Lefteris Kyprianou

Reputation: 327

Multiplication of each pair of rows in Pandas

Hello i have this dataset

Month   Value
Jan      15
Feb      2
Mar      8
Apr      4
May      9

How to achieve to have a new dataframe with the multiplication of each pair of the values of months?

For example something like this

     Jan   Feb   Mar   Apr   May
Jan   -    30    120   60    135
Feb   30   -     16    8     18
Mar   120  16    -     32    72
Apr   60   8     32    -     36
May   135  18    72    36    -

Upvotes: 1

Views: 154

Answers (2)

jcaliz
jcaliz

Reputation: 4041

Try matrix multiplication:

df.set_index('Month', inplace=True)
df_product = df @ df.T
# Fill nan in diagonal
df_product = df_product + np.where(np.eye(len(df_product)), np.nan, 0)

Upvotes: 1

anky
anky

Reputation: 75150

You can use a dot product with a transposed dataframe after setting Month as index, Then use a mask to ignore the matching index and columns:

u = df.set_index("Month")
v = u.dot(u.T)
m = list(v.columns)==v.index.to_numpy()[:,None]
out = v.mask(m)#.rename_axis(columns=None)

print(out)

Month    Jan   Feb    Mar   Apr    May
Month                                 
Jan      NaN  30.0  120.0  60.0  135.0
Feb     30.0   NaN   16.0   8.0   18.0
Mar    120.0  16.0    NaN  32.0   72.0
Apr     60.0   8.0   32.0   NaN   36.0
May    135.0  18.0   72.0  36.0    NaN

Upvotes: 2

Related Questions