Creation of an index with a year base

Question

I have a simple features panel data with the murders in the 32 Mexican states through 24 years. I want to create an index taking as a base the first year in my data (1994). To do so I am running the following code:

#Taking the data of murders in 1994 from each state and then paste it for all the years
mexico.sf$murders1994 <- mexico.sf$murders[mexico.sf$year==1994]

#Use the murders from each year divided by the murders in 1994 per state to create an index
    mexico.sf$murdersrelativeto1994 <- (mexico.sf$murders / mexico.sf$murders1994)

Nevertheless when I run the first code I got the following error:

Error: Assigned data `mexico.sf$murders[mexico.sf$year == 1994]` must be compatible with existing data.
x Existing data has 800 rows.
x Assigned data has 32 rows.
i Only vectors of size 1 are recycled.
Run `rlang::last_error()` to see where the error occurred.

It is clear to me that it is only taking 32 values because I am filtering per year, however, how can I copy those 32 data in all the sample?

Answer 1

Without looking at the actual data, I'm not sure I understand your purpose correctly. But if you need only to overwrite 800 values with the 32 values, maybe this way:

mexico.sf$murders1994 <- rep(mexico.sf$murders[mexico.sf$year==1994], 800/32)