[R-sig-Geo] Converting spatialPointsDataFrame into ppp

[GodinA]

Dear all,

I am new to spatial and point process analysis (as well as R), however most
of my Ph.D. will rely heavily on these tools *sighs :) I am starting a new
chapter where I intend to model elasmobranch i.e., shark and skate catch in
the Northwest Atlantic Canadian waters using point process modeling. I am
interested in investigating the spatial, temporal, and space–time clustering
of catch events conditioned upon the distribution of fishing locations. 

I have been following the R-sig-geo mails and found many great reading
suggestions, which were very helpful! Thank you. I would like to do some
exploratory data analysis on a small subset of my database i.e., solely
shark catch for the year 2009 (546 observations), but I am running (not
surprisingly) into errors and warnings!

Would be grateful to anyone's help!
I am trying to convert my SpatialPointsDataFrame into a ppp. Right now, I
would just like to make a ppp with "catch" as a mark (this is the catch size
in kg).

> class(SHK09)
[1] "SpatialPointsDataFrame"
attr(,"package")
[1] "sp"

#SHK09 looks as follow
> head(as.data.frame(SHK09))
  year month day tripID setID gear NAFO     x      y kept discard fmonth
fgear
1 2009     8  17    345    16    5   22 55.41 -58.46    0     227    Aug   
GN
2 2009     2   1      3     2    1   23 52.36 -51.24    0     450    Feb   
OT
3 2009     7  28    296     4    5    9 68.37 -59.34    0     250    Jul   
GN
4 2009     9   5    339    29    5    9 68.27 -59.53    0      10    Sep   
GN
5 2009     8  28    316    44    5    9 68.38 -64.36    0    1400    Aug   
GN
6 2009     9   1    316    49    5    9 69.26 -64.50    0     200    Sep   
GN
      fNAFO        t.spp.name t.spp.category         elasmo.name
elasmo.category
1        2H GREENLAND HALIBUT              0 SHARKS,DOGFISH (NS)              
1
2        2J GREENLAND HALIBUT              0     SHARK,GREENLAND              
1
3 BaffinIsd GREENLAND HALIBUT              0     SHARK,GREENLAND              
1
4 BaffinIsd GREENLAND HALIBUT              0     SHARK,GREENLAND              
1
5 BaffinIsd GREENLAND HALIBUT              0     SHARK,GREENLAND              
1
6 BaffinIsd GREENLAND HALIBUT              0     SHARK,GREENLAND              
1
  catch logcatch
1   227 5.429346
2   450 6.111467
3   250 5.525453
4    10 2.397895
5  1400 7.244942
6   200 5.303305

#I tried to do the following as suggested by prior email, however, I get
this following error message
>coordinates(SHK09) = ~x+y
Error in `coordinates<-`(`*tmp*`, value = ~x + y) : 
  setting coordinates cannot be done on Spatial objects, where they have
already been set

#so decided to proceed as follow
>catch <- as(SHK09["catch"], "ppp")
Error in as(SHK09["catch"], "ppp") : 
  no method or default for coercing "SpatialPointsDataFrame" to "ppp"

Ideas?
Thank you very much in advance!

~~Aurelie

Aurelie Cosandey-Godin
Ph.D. Candidate, Department of Biology, Dalhousie University
Industrial Graduate Fellow, WWF-Canada
Email: godina at dal.ca | Web: wormlab.biology.dal.ca
-----------------------------------------------------------------------------------------------------
Want to learn more about sharks in Atlantic Canada? Visit ShARCC!
www.atlanticsharks.org





--
View this message in context: http://r-sig-geo.2731867.n2.nabble.com/Converting-spatialPointsDataFrame-into-ppp-tp2764866p6801137.html
Sent from the R-sig-geo mailing list archive at Nabble.com.