Generating future dataframe with annual growth rate

Question

I am trying to generate annual data for a certain product when I have data for the base year and growth rate.

In the toy example, each product has different annual growth rate in efficiency by its ‘color’, and I want to generate yearly data until 2030.

Therefore, I have base year data (base_year) as follows:

    year    color   shape    efficiency
0   2018    red     circle   50
1   2018    red     square   30
2   2018    blue    circle   100
3   2018    blue    square   60

And each type of product’s growth rate (growthrate) as:

    color   rate
0   red     30
1   blue    20

Results I desire is:

    year    color   shape    efficiency
0   2018    red     circle   50
1   2018    red     square   30
2   2018    blue    circle   100
3   2018    blue    square   60
4   2019    red     circle   65
5   2019    red     square   39
6   2019    blue    circle   120
7   2019    blue    square   72
8   2020    red     circle   84.5
... (until 2030)

The data used in the toy code is..

base_year = pd.DataFrame(data = {'year': [2018,2018,2018,2018],
                     'color': ['red', 'red', 'blue', 'blue'],
                     'shape' : ['circle', 'square', 'circle', 'square'],
                     'efficiency' : [50, 30, 100, 60]}, columns = ['year', 'color', 'shape', 'efficiency'])

growthrate = pd.DataFrame(data = {'color': ['red', 'blue'],
                     'rate' : [30, 20]}, columns = ['color', 'rate'])

I’ve been trying some approach using .loc, but it seems such approach is quite inefficient.

Any suggestions or hints would be appreciated. Thank you in advance!

Asked By: H.Choi

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Source

Answer 1

Here is one way to do this:

years = 2031 - 2018

df = (pd.concat([df.assign(year=df['year']+i,
                          efficiency=df['efficiency']*((df['rate']/100+1)**i)) 
                for i, df in enumerate([base_year.merge(growthrate, on='color')] * years)])
      .drop('rate', axis=1))

Answered By: Chris Adams

Answer 2

what if it is GDP, and you have one value for the base year and just one growth rate, and you want to see what future gap values will be at the growth rate?

Answered By: Rutendo Chingosho

Generating future dataframe with annual growth rate

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