How can I create a csv file starting from a layer with some boundaries to a layer with others boundaries?

Question

I have a vector layer with the definition of the blocks of the state of NY, and I have another vector layer with the definition of the group blocks of the state of NY. They are two different vector layer (shapefiles).

I also have a CSV table with some extra information (population) with the field GISJOIN, and I can join this csv file with one vector layer, the block vector layer (that have the same field GISJOIN).

How can I do the join with the other group block vector layer?

My goal is to have a csv file compatible with the group block vector layer.

Answer 1

It sounds like you're trying to join population data (CSV) intended for census blocks (SHP) with census block groups (SHP).

If that's correct, I think you've got two options.

If you want to stick with your current data arrangement, you could do as @Mapperz suggested, and perform a spatial join. I would do this join based on the block centroids being within the block group. Here are some tips for doing this with QGIS:

• http://trendct.org/2015/05/29/tutorial-how-to-merge-data-from-two-different-maps-using-qgis/

• https://docs.qgis.org/2.14/en/docs/user_manual/working_with_vector/virtual_layers.html

I would recommend a second option, however, that makes the sort of spatial operation described above extraneous. And that is to just download the population data intended for block groups and do the join with the CSV table on that layer.