[R] map and shapefile help

[chuck.01]

Thanks you very much for your time Michael, and I have noted that this should
have been asked at the R-Sig-Geo site
cheers!


Michael Sumner-2 wrote
> 
> Sorry I take that back, I was using the (independent of GDAL)
> shapefile reader in maptools. Using the rgdal package, we get the full
> projection information from the auxiliary .xml file that ships with
> the other shapefile files.
> 
> library(rgdal)
> 
> ## Here my working directory "." contains "NA_CEC_Eco_Level3.shp"
> 
> x <- readOGR(".", "NA_CEC_Eco_Level3")
> OGR data source with driver: ESRI Shapefile
> Source: ".", layer: "NA_CEC_Eco_Level3"
> with 2548 features and 11 fields
> Feature type: wkbPolygon with 2 dimensions
> 
> 
> summary(x)
> Object of class SpatialPolygonsDataFrame
> Coordinates:
>        min     max
> x -4334052 3324076
> y -3313739 4267265
> Is projected: TRUE
> proj4string :
> [+proj=laea +lat_0=45 +lon_0=-100 +x_0=0 +y_0=0 +a=6370997 +b=6370997
> +units=m +no_defs]
> Data attributes:
>    NA_L3CODE
> ...
> 
> So, now we can do this:
> 
> library(maps)
> require(rgdal)
> 
> map("state", col = "aliceblue", fill = TRUE, lwd = 2)
> plot(spTransform(x, CRS("+proj=longlat +ellps=WGS84")), add = TRUE)
> 
> (Clearly I should have taken this to R-Sig-Geo some time ago).
> 
> Cheers, Mike.
> 
> 
> On Sun, Apr 1, 2012 at 6:09 PM, Michael Sumner <mdsumner@> wrote:
>> There is no coordinate system defined for these files- proj4string is
>> NA, see below - otherwise transforming them to that used by the maps
>> package is trivial. I suggest you find out the coordinate system from
>> the provider of the data and ask any further questions on R-Sig-Geo.
>> This is a big file, ~34 Mb and you should warn people of that.
>>
>> library(maptools)
>> x <- readShapeSpatial("NA_CEC_Eco_Level3.shp")
>>
>>  summary(x)
>> Object of class SpatialPolygonsDataFrame
>> Coordinates:
>>       min     max
>> x -4334052 3324076
>> y -3313739 4267265
>> Is projected: NA
>> proj4string : [NA]
>> Data attributes:
>>   NA_L3CODE                                           NA_L3NAME
>>  8.5.2  : 217   Mississippi Alluvial Plain                  : 217
>>  7.1.5  : 208   Coastal Western Hemlock-Sitka Spruce Forests: 208
>>  8.5.1  : 163   Middle Atlantic Coastal Plain               : 163
>>  8.5.3  : 147   Southern Coastal Plain                      : 147
>>  2.1.5  : 135   Foxe Uplands                                : 135
>>  8.1.8  :  98   Acadian Plains and Hills                    :  98
>>  (Other):1580   (Other)                                     :1580
>> ...
>>
>>
>>
>> On Sun, Apr 1, 2012 at 4:55 PM, Michael Sumner <mdsumner@> wrote:
>>> Try the R-Sig-Geo mailing list for a better target community, but if
>>> these
>>> are shapefiles there is read support in rgdal (or maptools for a simpler
>>> alternative) and if these are in long-lat like the maps package then
>>> plot(x,
>>> add=TRUE) will be most of the way there.
>>>
>>> If you need to transform either layer then see spTransform or project in
>>> rgdal.
>>>
>>> Cheers, Mike
>>>
>>>
>>> On Sunday, April 1, 2012, chuck.01 wrote:
>>>>
>>>> Hi,
>>>> I want to use map("state") and have the ecoregion shape (please see
>>>> link)
>>>> file projected onto this.
>>>>
>>>> ftp://ftp.epa.gov/wed/ecoregions/cec_na/NA_CEC_Eco_Level3.zip
>>>> ftp://ftp.epa.gov/wed/ecoregions/cec_na/NA_CEC_Eco_Level3.zip
>>>>
>>>> Could someone please show me how; I have never messed with this sort of
>>>> thing.
>>>> Thanks.
>>>>
>>>> --
>>>> View this message in context:
>>>> http://r.789695.n4.nabble.com/map-and-shapefile-help-tp4522794p4522794.html
>>>> Sent from the R help mailing list archive at Nabble.com.
>>>>
>>>> ______________________________________________
>>>> R-help@ mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide
>>>> http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>>>
>>> --
>>> Michael Sumner
>>> Institute for Marine and Antarctic Studies, University of Tasmania
>>> Hobart, Australia
>>> e-mail: mdsumner@
>>
>>
>>
>> --
>> Michael Sumner
>> Institute for Marine and Antarctic Studies, University of Tasmania
>> Hobart, Australia
>> e-mail: mdsumner@
> 
> 
> 
> -- 
> Michael Sumner
> Institute for Marine and Antarctic Studies, University of Tasmania
> Hobart, Australia
> e-mail: mdsumner@
> 
> ______________________________________________
> R-help@ mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 


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