Population same values by year for separate units based on one variable

[Chinmay Sharma]

Hi All,

I have data that resembles the following:

* Example generated by -dataex-. To install: ssc install dataex
clear
input float(country year population1 population2)
  1 1980 100 200
  1 1981 100 200
  1 1982 100 300
  1 1983 100 400
  .    .   .   .
  .    .   .   .
100 1980   .   .
100 1981   .   .
100 1982   .   .
100 1983   .   .
end

In the above, I have population data by country-year (population 1). In the above dataset, what I wish for is country 100 to contain data from the second column (population 2), by year, but to be replaced in population1 for the years 1980-1982. The dataset should finally look like:

* Example generated by -dataex-. To install: ssc install dataex
clear
input float(country year population1 population2)
  1 1980 100 200
  1 1981 100 200
  1 1982 100 300
  1 1983 100 400
  .    .   .   .
  .    .   .   .
100 1980 200   .
100 1981 200   .
100 1982 300   .
100 1983   .   .
end

Any help is much appreciated!

CS

[Andrew Musau]

bys year: egen ref= max(population2*(country==1))
replace population1= ref if country==100 & inrange(year, 1980, 1982)