In R, how can I join data by similar, but not identical, centroid (or numeric argument)?

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I'm building a transition matrix of land use change (state) over the years.

I'm therefore comparing shapefile years after years and build a dataframe with:

Landuse year1 - Landuse year2 - ....- ID- centroid

with the following function :

full_join(landuse1, landuse2, by="centroid")

where centroid is the actual centroid of the polygons. A centroid, is basically a vector of two numeric value.

However, the centroid, year after year, can slitghly shift (because the polygon actually change a little bit) leading in incomplete data gathering through the full_join function because centroid must exactly match.

I'd like to include a "more or less" argument, so that that any centroid close enough to the one from the year before can be joined to the datagrame for that particular polygon. But I'm not sure how ?

Thank you in advance.

r join
1 Answers

So the general term for what you are trying to do is called fuzzy matching. Im not sure how exactly it would work for the coordinates of a centroid. My Idea would be to calculate the distance between the Coordinates, and then set a margin of error, say 0.5%, and if they deviate from each other by less than that you could declare it a match. Basically loop through your list of locations and give the matches some unique ID, which you can then use for the join

user_198449090
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