At least in the US, CPI is an open formula: https://www.bls.gov/opub/hom/cpi/calculation.htm https://www.bls.gov/opub/hom/cpi/calculation.htm There is no way t

At least in the US, CPI is an open formula: https://www.bls.gov/opub/hom/cpi/calculation.htm https://www.bls.gov/opub/hom/cpi/calculation.htm There is no way to just present code that will compute it, though, because much of the detail lies in the data collection techniques, which rely on human judgement to replace discontinued or altered goods with equivalents, and they interview homeowners and renters in person via the Census. You can't reproduce the entire computation without employing a few thousand people in representative samples of the country.