Pandas Python Add Rows Based on the below condition

Question

I have an integer n=3

I have to create a square matrix with below condition when matrix[row]=matrix[column] then 1 else 0

My plan is to create a table, insert n number of rows with all nulls initially and write an update with the above case statement in pandas sql.

Can anyone please help on this case to create a dataframe initially with n rows and n columns dynamically?

Thank you.

sudeep · Accepted Answer · 2021-01-31 04:52:30Z

1

You can do something like this using numpy and pandas:

import numpy as np
import pandas as pd

def create_diagonal_matrix_of_size(n):
    if n > 0:
        d = np.diag(n * [1])
        df = pd.DataFrame(d)
        return df
    else:
        return pd.DataFrame()

print(create_diagonal_matrix_of_size(3))

answered Jan 31, 2021 at 4:52

sudeep

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3 Comments

rohith g Over a year ago

Thank you I want to use only Pandas & SQL concepts if possible thank you for your answer & quick response.

sudeep Over a year ago

Pandas uses numpy. So, if you are using Pandas, you have access to numpy already.

rohith g Over a year ago

I am sorry for asking a dumb question, if i do it below : for i in range(0,n,1): ... a.append(n) for i in range(0,len(a),1): c.append([a]) Can i create a Dataframe on above & write a sql update .... with Spark sql probably... I am just curios on time complexity space.....

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