[R-sig-Geo] Merging shapefiles and csv

[Rafael Wüest]

Hi there

have a look at

?sp::merge

Should do what you need.

HTH, Rafael

On 31/07/2014 15:14, Lyndon Estes wrote:
> I am not sure about the mismatch issue, but I thinking merging the
> data slot of spatialPolygonsDataFrame with a data frame produces
> undesirable results.
>
> I wrote a function a while back that does the merge in such a way that
> the problems are avoided, and perhaps this might help.  I think there
> are other, more recent, and undoubtedly better solutions (in fact I
> recall seeing a very recent thread about this, but not sure where)
> than this one that you could find.
>
> joinAttributeTable <- function(x, y, xcol, ycol) {
> # Merges data frame to SpatialPolygonsDataFrame, keeping the correct
> order. Code from suggestions at:
> # https://stat.ethz.ch/pipermail/r-sig-geo/2008-January/003064.html
> # Args:
> #   x: SpatialPolygonsDataFrame
> #   y: Name of data.frame to merge
> #   xcol: Merge column name
> #   ycol: Merge column name
> # Returns: Shapefile with merged attribute table
>
>    x$sort_id <- 1:nrow(as(x, "data.frame"))  # Column containing
> original row order for later sorting
>
>    x.dat <- as(x, "data.frame")  # Create new data.frame object
>    x.dat2 <- merge(x.dat, y, by.x = xcol, by.y = ycol)  # Merge
>    x.dat2.ord <- x.dat2[order(x.dat2$sort_id), ]  # Reorder back to original
>    x2 <- x[x$sort_id %in% x.dat2$sort_id, ]  # Make new set of
> polygons, dropping those which aren't in merge
>    x2.dat <- as(x2, "data.frame")  # Make update x2 into a data.frame
>    row.names(x.dat2.ord) <- row.names(x2.dat)  # Reassign row.names
> from original data.frame
>    x2 at data <- x.dat2.ord  # Assign to shapefile the new data.frame
>    return(x2)
> }
>
> Hope it helps.
>
> Best, Lyndon
>
>
> On Thu, Jul 31, 2014 at 8:32 AM, HallS <sam_l_cruickshank at hotmail.com> wrote:
>> Hi all,
>>
>> I'm struggling to know how this will come across as my data is confidential.
>>
>> Basically I have a shapefile (.shp) and a csv file while contain the same
>> regions (i.e.) a column which has the same information.  Using this link:
>> https://sites.google.com/site/eospansite/alobotips/spatial_r_tips/rshp_xls
>> I managed to get quite far but once I got to the writeOGR command, I get the
>> error
>>   Error in writeOGR(RSANHS, dsn = "C:/Users/Laptop/Documents/Rworkspace/",  :
>>    number of objects mismatch
>>
>> shape1 at data <- merge(shape1 at data,csv,by.x="RSA",
>> +                           by.y="RSA", all.x=T, sort=F)
>>>
>>> ###Checking it
>>> dim(shape at data)
>> [1] 1745    2
>>> dim(shape1 at data)
>> [1] 1747    5
>>
>> This shows a discrepancy in two rows between the original shapefile and the
>> new merged one.  When I looked at the merged file in full, there were a
>> number of NA rows at the bottom where there was no corresponding data to the
>> shapefile.  I tried shape1 at data <- na.exclude(shape1 at data) and with na.omit,
>> and this did reduce the number of rows to 1690, but the problem persists.
>>
>> Sorry if this is a really unhelpful question, I'm not sure how to do it when
>> data is confidential.
>>
>>
>>
>> --
>> View this message in context: http://r-sig-geo.2731867.n2.nabble.com/Merging-shapefiles-and-csv-tp7586839.html
>> Sent from the R-sig-geo mailing list archive at Nabble.com.
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo at r-project.org
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo at r-project.org
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>

-- 
Rafael Wüest
rafael.wueest at gmail.com
http://www.rowueest.net