How to add a value in dataframe matrix from another dataframe?

April 16, 2022

I am working on a dataset. I have one dataset which has three column company SIC code, the second column is also a company SIC code , and third column is their relationship score between two SIC code.

first dataframe

SIC SIC.1 value

10    10    0

10    12    15

10    15    17.9

and second data frame is empty data frame with SIC code in index and column

   10  12   13

10
12
13

so I have to write a value in this second dataframe using value column from first dataframe ?

code is

for k in df20.index:
    for i in df21.index:
        for j in df21.columns:
            a = int(i)
            b = int(j)
            if df20["SIC"][k] == a & df20["SIC.1"][k] == b:
                m = df20["value"][k]
                df21[i][j] = m
            else:
                continue

please look into it, I don’t know where I am making the mistake.

>Solution :

import pandas as pd

df20 = pd.DataFrame([
    [10, 10, 0],
    [10, 12, 15],
    [10, 15, 17.9],
], columns=['SIC', 'SIC.1', 'value'])

df21 = pd.DataFrame(
    index=[10, 12, 13], columns=[10, 12, 13]
)

for i, row in df20.iterrows():
    for SIC in df21.index:
        for SIC1 in df21.columns:
            if row['SIC'] == SIC and row['SIC.1'] == SIC1:
                df21.loc[SIC, SIC1] = row['value']
print(df21)