Help merging two datasets using geo info

[Linda Estelí Méndez]

Hi all,

I apologize if this is a stupid question. I've been asking around, tried to use stackoverflow etc, and haven't been able to make this work. Hope someone here can help me!

What I want to do:

I have two datasets - "agency" and "casgem". "casgem" is a shapefile with information of groundwater basins in California. "agency" is a dataset I've been trying to compile with a couple columns that have shapefile information and also another column "BasinNo" with is an ID for the groundwater basin in which agencies are located. My goal is to somehow match the datasets in a way that I know where is each agency located, so basically have information in the "BasinNo" for each agency.

Thanks to anyone has any idea. I've tried to use over (sp package) but didn't really get anywhere...

Warm regards,

Linda.

[Ryan Peek]

Hi Linda,

I think what you are requesting is along these lines...but I'm not sure. Take a look.

library(rgdal)

# read in shape

gw <- readOGR(dsn = "data/shp", layer="CASGEM_Groundwater_Basin_Prioritization")

# quick plot

plot(gw)

# read in Agency data

agency<- read.csv("data/shp/agency.csv")

# make a new copy of Spatial Polygons

gw2 <- gw

# view summary of data

summary(agency)

summary(gw2@data)

# join on Basin, make sort F to retain spatial order

gw2@data <- merge(gw2@data, agency, by.x="BAS_SBBSN", by.y="BasinNo", sort=F)

# plot

plot(gw2, col=gw2$OWNERSHIP)

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Ryan Peek

PhD Candidate, Graduate Group in Ecology

Center for Watershed Sciences, UC Davis

ryanpeek.github.io

@riverpeek

530.754.5351 

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[Linda Estelí Méndez]

Hi Ryan,

Thanks for answering! 

I checked what you did and yes this is what I want to do, but the outcome you got has only 189 agencies. The 'agency' dataset has 1239 agencies. The majority of those agencies have geographic information in a column called Shape_STAr and Shape_STLe and 189 of those agencies have information in the "BasinNo" that I inputed by hand. So basically with the code, R recognized those hand-written agencies that already have a BasinNo ID, but what I am trying to avoid is to handwrite that for over a thousand agencies. So what I really want to do is use that Shapefile information in those columns and see if we can do a merge with that, in the absence of having a BasinNo for the agencies. I don't even know if its possible, but worth asking.

Thanks so much for your help!!

Linda.

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Linda Estelí Méndez

http://www.linkedin.com/in/lindaestelimendez

[Ryan Peek]

Hi Linda, 

I think you'd need to use the same approach, but unless you have some sort of cross-walk column (something with joinable information in both), you may have trouble getting this to work as it currently exists. I'm not sure what Shape_STAr field you could join with in the shp file...is that a location (UTM or coordinate field)?

Any chance there's another (third) table of data with metadata or spatial data that you could use to join to the two you sent? If so, you could use the (third) data table that has some replicable field with both your shp and the agencies, and then join (or crosswalk) to one or both of the tables as you need. 

Another option would be getting the agency jurisdiction info from another shapefile and joining by agency (check out CPAD or CA land ownership...they have pretty detailed info you might be able to use). You could also try using something like you mentioned earlier, the "over()" function if you have two spatial polygon/point files to extract that info. 

Not sure what else I can do to help...come by the D-RUG meeting on Tuesday at 10am and we can take a look. 

Adios,

Ryan

[Erica Rettig]

What are Shape_STAr and Shape_STLe, exactly? It's solvable if you have more information about the geography

Thanks,

Erica

Erica Rettig

PhD Candidate

Graduate Group in Ecology, UC Davis