Constant dollar transformations

Overview

The function const2curr computes the equivalent generic cashflow in current dollars from a generic cashflow in constant dollars of the date given by base_date. inflation is the inflation rate per compounding period. curr2const computes the inverse transformation.

Functions in this module

cashflows.inflation.const2curr(cflo, inflation, base_date=0)[source]

Converts a cashflow of constant dollars to current dollars of the time base_date.

Parameters:
  • cflo (pandas.Series) – Generic cashflow.
  • inflation (pandas.Series) – Inflation rate per compounding period.
  • base_date (int, str) – base date.
Returns:

A cashflow in current money (pandas.Series)

Examples.

>>> cflo=cashflow(const_value=[100] * 5, start='2000', freq='A')
>>> inflation=interest_rate(const_value=[10, 10, 20, 20, 20], start='2000', freq='A')
>>> const2curr(cflo=cflo, inflation=inflation) 
2000    100.00
2001    110.00
2002    132.00
2003    158.40
2004    190.08
Freq: A-DEC, dtype: float64

>>> const2curr(cflo=cflo, inflation=inflation, base_date=0) 
2000    100.00
2001    110.00
2002    132.00
2003    158.40
2004    190.08
Freq: A-DEC, dtype: float64

>>> const2curr(cflo=cflo, inflation=inflation, base_date='2000') 
2000    100.00
2001    110.00
2002    132.00
2003    158.40
2004    190.08
Freq: A-DEC, dtype: float64

>>> const2curr(cflo=cflo, inflation=inflation, base_date=4) 
2000     52.609428
2001     57.870370
2002     69.444444
2003     83.333333
2004    100.000000
Freq: A-DEC, dtype: float64

>>> const2curr(cflo=cflo, inflation=inflation, base_date='2004') 
2000     52.609428
2001     57.870370
2002     69.444444
2003     83.333333
2004    100.000000
Freq: A-DEC, dtype: float64
cashflows.inflation.curr2const(cflo, inflation, base_date=0)[source]

Converts a cashflow of current dollars to constant dollars of the date base_date.

Parameters:
  • cflo (pandas.Series) – Generic cashflow.
  • inflation_rate (float, pandas.Series) – Inflation rate per compounding period.
  • base_date (int) – base time..
Returns:

A cashflow in constant dollars

 
>>> cflo = cashflow(const_value=[100] * 5, start='2015', freq='A')
>>> inflation = interest_rate(const_value=[10, 10, 20, 20, 20], start='2015', freq='A')
>>> curr2const(cflo=cflo, inflation=inflation) 
2015    100.000000
2016     90.909091
2017     75.757576
2018     63.131313
2019     52.609428
Freq: A-DEC, dtype: float64

>>> curr2const(cflo=cflo, inflation=inflation, base_date=4) 
2015    190.08
2016    172.80
2017    144.00
2018    120.00
2019    100.00
Freq: A-DEC, dtype: float64

>>> curr2const(cflo=cflo, inflation=inflation, base_date='2017') 
2015    132.000000
2016    120.000000
2017    100.000000
2018     83.333333
2019     69.444444
Freq: A-DEC, dtype: float64