Why am I getting this error? Here is the R script and the data set I am trying to plot salinity contours for (link to data here): It looks like this (first 10 rows):
Longitude Latitude Salinity
1 -76.7027969 35.8915787 0.094745182
2 -76.67744141 35.8915787 0.10131969
3 -76.65208591 35.8915787 0.109281363
4 -76.62673042 35.8915787 0.118873653
5 -76.60137493 35.8915787 0.130326379
6 -76.57601943 35.8915787 0.143826847
7 -76.55066394 35.8915787 0.159496078
8 -76.52530845 35.8915787 0.177391073
9 -76.49995296 35.8915787 0.197562864
10 -76.47459746 35.8915787 0.220200511
ASsalinity <- read.csv("~/ASsalinity.csv")
library("ggplot2")
library("directlabels")
plot1<-ggplot(ASsalinity)+geom_raster(aes(Longitude,Latitude,fill = Salinity),data=ASsalinity)+geom_contour(aes(Longitude,Latitude,z=Salinity),data=ASsalinity)
plot1
I can get the contours plotted on the ggmap, A plot of the salinity contours in Albemarle Sound, NC. Longitude (x) and Latitude (y), and an interpolation program was used to generate the salinity at all other points on a grid.
but the direct.label command is throwing this error:
direct.label (plot2)
If the defaults are used:
Error in (function (geom, p, L, colvar, ...) :
No default label placement for this type of ggplot
If I specify a position placement:
direct.label (plot2, "bottom.pieces")
I get a different error:
'ggproto' is not an exported object from 'namespace:ggplot2'
What am I doing wrong?
Thanks in advance.
So I discovered the answer to my own question, with the help of aosmith. The key was upgrading to ggplot2 2.1.0 and then using stat_contour(). Below, I updated my code, while adding a base map with ggmap 2.6.1:
library("ggmap")
library("ggplot2")
library("directlabels")
ASmap3<-get_map(location= c(lon= -76.16,lat=36.08),zoom=9)
plot1<-ggmap(ASmap3)+stat_contour(aes(Longitude,Latitude,z=Salinity,colour=..level..),data=ASsalinity)
direct.label(plot1,"bottom.pieces")
Here is the map: A map of Albemarle Sound, NC, USA with labeled salinity contours
