I am trying to make a map about residential properties in 3 neighborhoods in Oakland, California. I already have the shapefile for all the parcels and blocks, but I need to find data that indicate which and which specifically is a residential property, and highlight them all to see the distribution of residential propoerties.
Not sure where you got your data. In Alameda County, if your data has Use Code or Use Description, use that. If it just has Use Code, then check this chart here for residential uses, Alameda County Assessor Use Codes
If it has neither, you could download this table that has use codes, then join it to your shapefile and assign residential based on the Use Code chart. Assessor's Tax Roll Table with Parcel Use Codes
I thought you could download the Use Code and Use Description with the Parcels, but doesn't come with their parcels on their open data site.
Just another comment regarding the zoning: zoning is what is permitted, not what is necessarily on the ground. There could be huge swaths of vacant land zoned as a residential neighborhood. But there are no residents or houses. The assessor's use will tell you that it is vacant or something similar.
If you are looking for the allowed residential areas going forward, use zoning. If you are looking for on the ground conditions, use Assessor codes.