[R] Getting unknown error trying to plot spatial data

[Jim Lemon]

On 08/05/2012 05:09 AM, mjkatsaros wrote:
> Hi there! I'm following an awesome guide to working with spatial data
> (http://www.frankdavenport.com/blog/2012/6/19/notes-from-a-recent-spatial-r-class-i-gave.html)
> and am running into an error that I can't figure out how to fix.
>
> Disclaimer: I am very much an R n00b
>
> Here is the r script I am running:
> https://dl.dropbox.com/u/28231177/This%20Should%20Work.R
>
> data: https://dl.dropbox.com/u/28231177/my_data.csv
>
> shapefile: https://dl.dropbox.com/u/28231177/sfzipcodes.zip
>
> I am getting two errors:
>
>> pds<- fortify(sf_map)
> *Using OBJECTID to define regions.*
>> pds$OBJECTID<- as.integer(pds$OBJECTID)
> *Error in `$<-.data.frame`(`*tmp*`, "OBJECTID", value = integer(0)) :
>    replacement has 0 rows, data has 16249*
>> 	
>>
>> ## Make the map
>>
>> p1<- ggplot(my_data, aes(map_id = zip))
>> p1<- p1 + geom_map(aes(fill=vol, map_id = zip), map = pds)
>> p1<- p1 + expand_limits(x = pds$lon, y = pds$lat) + coord_equal()
>> p1 + xlab("Basic Map with Default Elements")
> *Error in unit(x, default.units) : 'x' and 'units' must have length>  0*
>
> Anybody have any idea what is happening here or how to resolve this?

Hi mjkatsaros,
The data file doesn't have a column labelled "OBJECTID". I would try 
renaming the "zip" column to "OBJECTID".

Jim