Specifying spatial coordinates in a data.frame

Question

Pretty silly but I can't figure out what I'm doing wrong here:

I have a data.frame with 2 columns:

df = data.frame(x = rep(1, 20), y = runif(20, 10,20))

I then want to set x and y as spatial coordinates so I can plot df in a bubble plot. So I try:

coordinates(df) = c("x","y")

But then:

bubble(df)

gives this error:

Error in data.frame(x@data, x@coords) : 
  arguments imply differing number of rows: 0, 20

you probably want to include a `library(sp)` in your example. And perhaps a `set.seed(1)` as well ;) — Ricardo Saporta, Apr 28 '14 at 06:02
temporary workaround: try adding a dummy column to `df` before calling the coordinates() function — Ricardo Saporta, Apr 28 '14 at 06:06
Thanks a lot Ricardo. Sorry for not including library(sp) in my example and the dummy column did the trick. — user1701545, Apr 28 '14 at 06:09

score 1 · Answer 1 · answered Apr 28 '14 at 06:47

For bubble plot to be meaningful, you should probably create a SpatialPointsDataFrame.

library(sp)
df <- data.frame(x = rep(1, 20), y = runif(20, 10,20))
data <- data.frame(variable = runif(20))
coordinates(df) <- ~ x + y
out <- SpatialPointsDataFrame(df, data)
bubble(out)

enter image description here

score 0 · Answer 2 · answered Apr 28 '14 at 06:13

0

library(sp)
set.seed(1)
df = data.frame(x = rep(1, 20), y = runif(20, 10, 20), dummy = rep(0, 20))
coordinates(df) = c("x","y")
bubble(df)

enter image description here

answered Apr 28 '14 at 06:13

user1701545

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And the explanation? I suppose `bubble` expects a `SpatialPointsDataFrame` not just `SpatialPoints`? – jbaums Apr 28 '14 at 06:15

Specifying spatial coordinates in a data.frame

2 Answers2