I have been working on earthquake data that has lat long values, and I want to convert those lat long values to spatial coordinates.
Suppose I have the following data set df
:
longitude latitude
128.6979 -7.4197
153.0046 -4.7089
104.3261 -6.7541
124.9019 4.7817
126.7328 2.1643
153.2439 -5.6500
142.8673 23.3882
152.6890 -5.5710
I want to convert it into spatial points. Something like this:
lon lat
[1,] 2579408.24 1079721.15
[2,] 2579333.69 1079729.18
[3,] 2579263.65 1079770.55
[4,] 2579928.04 1080028.46
[5,] 2579763.65 1079868.92
[6,] 2579698.00 1079767.97
I used the following code:
library(sp)
df.sp<-df
coordinates(df.sp)<-~x+y
But I receive the following error:
Error in `[.data.frame`(object, , -coord.numbers, drop = FALSE) :
undefined columns selected
First, you take the columns of lon
and lat
and create an object for coord
. Then, you subtract them from the original data frame and create a new object. You finally use SpatialPointsDataFrame()
to create a SpatialPointsDataFrame
. When you create a SpatialPointsDataFrame
, you need to assign proj4string
. Choose an appropriate one for you.
In your case, you do not have any other columns but lon
and lat
, the method won't work. I purposely left lon
and lat
@data.
DATA
mydf <- structure(list(longitude = c(128.6979, 153.0046, 104.3261, 124.9019,
126.7328, 153.2439, 142.8673, 152.689), latitude = c(-7.4197,
-4.7089, -6.7541, 4.7817, 2.1643, -5.65, 23.3882, -5.571)), .Names = c("longitude",
"latitude"), class = "data.frame", row.names = c(NA, -8L))
### Get long and lat from your data.frame. Make sure that the order is in lon/lat.
xy <- mydf[,c(1,2)]
spdf <- SpatialPointsDataFrame(coords = xy, data = mydf,
proj4string = CRS("+proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0"))
#> str(spdf)
#Formal class 'SpatialPointsDataFrame' [package "sp"] with 5 slots
#..@ data :'data.frame': 8 obs. of 2 variables:
#.. ..$ longitude: num [1:8] 129 153 104 125 127 ...
#.. ..$ latitude : num [1:8] -7.42 -4.71 -6.75 4.78 2.16 ...
#..@ coords.nrs : num(0)
#..@ coords : num [1:8, 1:2] 129 153 104 125 127 ...
#.. ..- attr(*, "dimnames")=List of 2
#.. .. ..$ : NULL
#.. .. ..$ : chr [1:2] "longitude" "latitude"
#..@ bbox : num [1:2, 1:2] 104.33 -7.42 153.24 23.39
#.. ..- attr(*, "dimnames")=List of 2
#.. .. ..$ : chr [1:2] "longitude" "latitude"
#.. .. ..$ : chr [1:2] "min" "max"
#..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slot
#.. .. ..@ projargs: chr "+proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0"