Proj4 reprojection using R

Question

Hi,

I am trying to reproject coordinates from WGS84 to MGA Zone 53, a UTM projection based on the GDA94 datum. I get infinity as my result, which is definitely incorrect. I am using R's proj4 package like so:

> library(proj4)
> df <- data.frame("x" = c(131.1, 131.102, 131.1106, 133.34), "y" = c(-13.23, -13.243, -13.22, -22.66))
> df
         x       y
1 131.1000 -13.230
2 131.1020 -13.243
3 131.1106 -13.220
4 133.3400 -22.660
> ptransform(data = df, src.proj = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs", dst.proj = "+proj=utm +zone=53 +south +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs")
$x
[1] Inf Inf Inf Inf

$y
[1] Inf Inf Inf Inf

$z
[1] 0 0 0 0

> 

What is going wrong here?

Answer 1

Where is the proj4 package obtained from?

Try rgdal if you can install it:

df <- data.frame("x" = c(131.1, 131.102, 131.1106, 133.34), "y" = c(-13.23, -13.243, -13.22, -22.66))

library(rgdal)

## project expects a matrix, assumes source is longlat/WGS84

project(as.matrix(df), "+proj=utm +zone=53 +south +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs")

     [,1]    [,2]

[1,] 77177.18 8534132

[2,] 77416.79 8532695

[3,] 78310.75 8535258

[4,] 329440.68 7493165

Answer 2

The problem is that ptransform expects radians, not degrees. The function proj4:::project defaults to degrees. The results are the same with ptransform if you convert to radians.