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USE the above row to calculate the value for below row iteratively using pandas dataframe

August 22, 2022

I want create dataframe by reusing the above row to calculate the value of below row.
Currently I am using variables to stores values and creating list and pushing list to cf dataframe to calculate Discount Cash Flows.

Current Reproducible code-

import math
import pandas as pd

#User input
cashflow = 3.6667
fcf_growth_for_first_5_years = 14/100
fcf_growth_for_last_5_years = 7/100
no_of_years = 10
t_g_r = 3.50/100 ##Terminal Growth Rate
discount_rate = 10/100

##fcf calculaton for 10 Years
future_cash_1_year = cashflow*(1+fcf_growth_for_first_5_years)
future_cash_2_year = future_cash_1_year*(1+fcf_growth_for_first_5_years)
future_cash_3_year = future_cash_2_year*(1+fcf_growth_for_first_5_years)
future_cash_4_year = future_cash_3_year*(1+fcf_growth_for_first_5_years)
future_cash_5_year = future_cash_4_year*(1+fcf_growth_for_first_5_years)
future_cash_6_year = future_cash_5_year*(1+fcf_growth_for_last_5_years)
future_cash_7_year = future_cash_6_year*(1+fcf_growth_for_last_5_years)
future_cash_8_year = future_cash_7_year*(1+fcf_growth_for_last_5_years)
future_cash_9_year = future_cash_8_year*(1+fcf_growth_for_last_5_years)
future_cash_10_year = future_cash_9_year*(1+fcf_growth_for_last_5_years)

fcf = []
fcf.extend(value for name, value in locals().items() if name.startswith('future_cash_'))

cf = pd.DataFrame()
cf.insert(0, 'Sr_No', range(1,11))
cf.insert(1, 'Year', range(23,33))
cf['fcf'] = fcf
cf

Desired Output-

I am getting desired output by using lst method code as given above, but I am looking for more efficient way to calculate values using pandas df instead of using lst & variables.


  Sr_No Year    fcf
0   1   23  4.180038
1   2   24  4.765243
2   3   25  5.432377
3   4   26  6.192910
4   5   27  7.059918
5   6   28  7.554112
6   7   29  8.082900
7   8   30  8.648703
8   9   31  9.254112
9   10  32  9.901900

>Solution :

Using a for loop makes this much more easier to handle

import math
import pandas as pd

#User input
cashflow = 3.6667
fcf_growth_for_first_5_years = 14/100
fcf_growth_for_last_5_years = 7/100
no_of_years = 10
t_g_r = 3.50/100 ##Terminal Growth Rate
discount_rate = 10/100

cf = pd.DataFrame()
cf.insert(0, 'Sr_No', range(1,11))
cf.insert(1, 'Year', range(23,33))

##fcf calculaton for 10 Years
fcf=[]
for row in range(len(cf)):
    if cf.Sr_No[row]==1:
        fcf.append(cashflow*(1+fcf_growth_for_first_5_years))
    elif cf.Sr_No[row]<6:
        fcf.append(fcf[row-1]*(1+fcf_growth_for_first_5_years))
    else:
        fcf.append(fcf[row-1]*(1+fcf_growth_for_last_5_years))
cf['fcf'] = fcf
cf