[R-sig-Geo] sp package seems to round my coordinates

[Roger Bivand]

On Thu, 8 Sep 2011, Pascal Title wrote:

> Hi
>
> I have a dataframe containing coordinates and metadata that I am converting
> to SpatialPointsDataFrame using the function from the sp package.
> However, I have noticed that the resulting coordinates have fewer decimal
> places than my original data. This is problematic for me because later on I
> will be using these coordinates to match them with the original records in
> order to retrieve other information.
>
> Is there any way I can have the function keep my coordinates as is?

This is a FAQ - you are mistaking the internal representation, which 
retails precision, with the displayed representation, which uses the 
default number of digits set by options() for all print() methods. So when 
you print splisttemp, you are actually saying:

print(splisttemp)

and could say:

print(splisttemp, digits=4)
print(splisttemp, digits=12)

or equivalently set the option to another value, with different output.

See:

set.seed(1)
x <- rnorm(10)
print(x)
print(x, digits=4)
print(x, digits=14)

Hope this clarifies,

Roger

> Here is an example:
>
>> splisttemp
>   DecimalLongitude DecimalLatitude SpAbbr InstitutionCode CatalogNumberText
> 1         -76.87271       3.6628163 BanRot       EBIRD_COL       OBS81997559
> 2         -76.97495       3.7168289 BanRot          AUDCLO       OBS89767945
> 3         -76.88397       3.6160872 BanRot          AUDCLO       OBS89769896
> 4         -77.51667       5.5166667 BanRot            AMNH       Skin-123476
> 5         -76.03337       4.8666900 BanRot            LACM             34848
> 6         -78.43333       1.4333333 BanRot           LSUMZ             38939
> 7         -78.55000       0.9500000 BanRot            ANSP            182799
> 8         -79.21389       0.4719444 BanRot          AUDCLO       OBS58485973
> 9         -78.51036       0.8953493 BanRot          AUDCLO       OBS84822747
> 10        -78.37810       1.5102800 BanRot          AUDCLO       OBS67916517
> 11        -75.15000       7.0700000 BanRot   8110002317-09         4743-5160
>
>>
> SpatialPointsDataFrame(coords=splisttemp[,c("DecimalLongitude","DecimalLatitude")],data=splisttemp[,c("SpAbbr","InstitutionCode","CatalogNumberText")],proj4string=CRS("+proj=longlat
> +datum=WGS84"))->tempshp
>> tempshp
>            coordinates SpAbbr InstitutionCode CatalogNumberText
> 1   (-76.8727, 3.66282) BanRot       EBIRD_COL       OBS81997559
> 2   (-76.9749, 3.71683) BanRot          AUDCLO       OBS89767945
> 3    (-76.884, 3.61609) BanRot          AUDCLO       OBS89769896
> 4   (-77.5167, 5.51667) BanRot            AMNH       Skin-123476
> 5   (-76.0334, 4.86669) BanRot            LACM             34848
> 6   (-78.4333, 1.43333) BanRot           LSUMZ             38939
> 7        (-78.55, 0.95) BanRot            ANSP            182799
> 8  (-79.2139, 0.471944) BanRot          AUDCLO       OBS58485973
> 9  (-78.5104, 0.895349) BanRot          AUDCLO       OBS84822747
> 10  (-78.3781, 1.51028) BanRot          AUDCLO       OBS67916517
> 11       (-75.15, 7.07) BanRot   8110002317-09         4743-5160
>
> Thanks for your help!
>
> -Pascal
>

-- 
Roger Bivand
Department of Economics, NHH Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no