Hi Rui,
I think the following should give you what you are looking for:
res$area2 = sapply(slot(res,"polygons"), function(x) slot(x, "area"))
Cheers,
Jon
On 13-Dec-11 13:50, Rui Catarino wrote:
Dear all,
This may seem a very obvious question but I'm suck and for the past 2h I
haven't been able of solving the problem. So for the sake of
productivity I'll ask for some help:
I have a SpatialPolygon Class that looks like(see bellow) in the example
below I have only 2 polygons but they will be thousands. What I'm trying
to achieve is a list with the total area of each polygon.
Thanks in advance
str(res)
Formal class 'SpatialPolygons' [package "sp"] with 4 slots
..@ polygons :List of 2
.. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
.. .. .. ..@ Polygons :List of 9
.. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
.. .. .. .. .. .. ..@ labpt : num [1:2] 3.19 51.68
.. .. .. .. .. .. ..@ area : num 8.96e-05
.. .. .. .. .. .. ..@ hole : logi FALSE
.. .. .. .. .. .. ..@ ringDir: int 1
.. .. .. .. .. .. ..@ coords : num [1:5, 1:2] 3.18 3.18 3.19 3.2 3.18
...
.
.
.
.. .. .. ..@ plotOrder: int [1:9] 9 8 2 3 1 4 7 5 6
.. .. .. ..@ labpt : num [1:2] 3.14 51.67
.. .. .. ..@ ID : chr "2"
.. .. .. ..@ area : num 0.000993
..@ plotOrder : int [1:2] 2 1
..@ bbox : num [1:2, 1:2] 3.09 51.66 3.26 51.73
.. ..- attr(*, "dimnames")=List of 2
.. .. ..$ : chr [1:2] "x" "y"
.. .. ..$ : chr [1:2] "min" "max"
..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slots
.. .. ..@ projargs: chr NA
Rui Catarino
Scientific Officer
Fishery Systems Group
Marine Scotland - Science
Scottish Government | 36 |B |Marine Laboratory, PO Box 101| 375,
Victoria Road | Aberdeen AB11 9DB
Tel: +44 (0)1224 295572
Mob:+44 (0)7530 240666
Fax: +44 (0)1224 295511
e: r.catar...@marlab.ac.uk
w: http://www.scotland.gov.uk/marinescotland
<http://www.scotland.gov.uk/marinescotland>
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