CODEWITHSUNDEEP
rspatial
killbot2000
killbot2000

Reputation: 59

Why does R think the projection data are different?

I'm working with satellite tracked animals and have a load of relocation data.

So I have my map data and relocations as SpatialPointsDataFrames and when I ask

if proj4string(map)==proj4string(locs) I get TRUE.

But when I try the count.points function as follows 

cp <- count.points(locs, map)

I get the following error 

Error in count.points(SpatialPoints(x), w) : 
  different proj4string in w and xy

Does anyone have any ideas on why this is the case?

Edit Code:

load("mydata") 
map = mydata$map 
map 
mimage(map) 
locs= mydata$relocs 
locs 
image(map) 
points(locs, col=as.numeric(slot(locs, "data")[,1]), pch=16) 
cp <- count.points(locs, map)

Upvotes: 2

Views: 989

Answers (1)

Ari B. Friedman
Ari B. Friedman

Reputation: 72731

Reproducible example would go a long, long way here. But generally speaking R's comparison of projection strings is approximately verbatim. So if there's an extra space or so forth, it will fail.

Given the out for proj4string(map), proj4string(locs), proj4string(SpatialPoints(locs)) in the comment, particularly that proj4string(SpatialPoints(locs)) is NA, I'd say that count.points is dropping the proj4string when it changes to a SpatialPoints object. I think the way to coerce a SPDF to SP while keeping the projection string is via as(x,"SpatialPoints").... Try using trace to insert that into count.points?

Upvotes: 2

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